Intention to donate blood and its predictors among adults of Gondar city: Using theory of planned behavior.

BACKGROUND: Blood transfusion is a lifesaving procedure when someone encounters severe anemia, accident or injury, surgery, heavy bleeding during childbirth and cancer chemotherapy. The average blood donation rate of Africa is 4.7/1000 inhabitants and Ethiopia is among one of the countries with the lowest annual donation rate which is 0.8/1000 population. This study assessed intention to donate blood on adults of Gondar city administration using the theory of planned behavior.
METHODS: A community-based cross-sectional study was conducted. The study was conducted on two randomly selected Gondar sub-cities using systematic sampling on a sample size of 524 adults. Epi Data version 3.0 and STATA version 14 were used for entry and analysis of data respectively. Multiple linear regression was carried out to see the association between intention and sociodemographic variables, past donation experience, attitude, subjective norm and perceived behavioral control and with 95% confidence interval and a p-value of less than 0.05 was used to detect statistical significance.
RESULTS: A total of 515 respondents participated in the study giving a response rate of 98%. Most of the participants were females (66.4%) and the participants' age ranges from 18 to 65 years. The variance explained by the model was 49%. The mean intention to donate blood was 3.02±1.13. Direct perceived behavioural control (β = 0.14, CI (0.04, 0.23)), direct subjective norm (β = 0.11: CI (0.04, 0.17), direct attitude (β = 0.03; CI (0.01, 0.06)) and past behaviour of blood donation (β = 0.3; CI (0.07, 0.51) were significant predictor of intention.
CONCLUSION: Theory of planned behavior could be successfully applied in determining adult's blood donation intention. Predictors of intention to donate blood were past experience of blood donation, direct subjective norm, direct perceived behavioural control and direct attitude. None of the external variables predict blood donation intention.

Introduction

Blood is essential to life and circulates through our body and delivers oxygen and nutrients to the body’s cells. It has no substitute and cannot be made or manufactured. Generous blood donors are the only source of blood for patients in need of a blood transfusion[1-3].

Blood transfusion is a lifesaving procedure given to someone in need of it when encounters anemia(severe iron deficiency, thalassemia or aplastic anemia), accident or injury, undergo major surgery, during childbirth and cancer chemotherapy[4].

Globally millions of lives have been saved through blood transfusion each year. However, its availability is the main concern of developing countries[5]. The average blood donation rate of Africa is 4.7/1000 inhabitants and Ethiopia is among one of the countries with the lowest annual donation rate (0.8/1000) population [6].

According to the Ethiopia Health sector transformation plan (HSTP) report of 2015/16, it was planned to collect 202,000 units of blood but the collected was 169, 744 units of blood [7].

Providing adequate and safe blood to those who need blood is the responsibility of blood banks. Blood could be obtained from voluntary non- remunerated donors, family replacement remunerated or paid donors, and autonomous donors[8] but the safest way is blood obtained from voluntary non- remunerated donors.

According to the theory of planned behavior, human action is guided by three kinds of considerations. The first is behavioral beliefs which is beliefs about the likely outcomes of the behavior and the evaluations of these outcomes. The second is normative beliefs; it is beliefs about the normative expectations of others and motivation to comply with these expectations. The last is control beliefs which is beliefs about the presence of factors that may facilitate or impede performance of the behavior and perceived power of these factors[9]. Intention is the most proximal and best predictor of behaviour and intention is further predicted by the attitude towards blood donation[10], subjective norms associated with blood donation and perceived behavioral control over blood donation. Across different researches theory of planned behavior has a potential to predict blood donation, and the predictors of theory planned behavior explained between 51% and 80.7% of variances to donate blood[9-11]. Therefore this study aims to assess intention towards blood donation of adults using the theory of planned behavior[12].

Rationale of the study

There is a deficit between the amount of blood needed and collected. Different studies conducted in Ethiopia on blood donation show that the rate of blood donation is still very low. In developing countries like Ethiopia the most source of blood is obtained from voluntary individuals, and most of it is collected through campaign because there are no regular blood donors. This study assessed predictors (attitude, subjective norm, perceived behavioural control and past donation behaviour) of intention to donate blood. Furthermore, the study finding may help policy makers and health professionals in developing new approach for increasing blood donation practice among adults.

Methods

Study design and setting

A community-based cross-sectional study was conducted from 1st March to 30th March 2019 among adults of Gondar city to assess intention to donate blood and its predictors using theory of planned behavior. Gondar city is located about 727 km away from Addis Ababa, the capital city of Ethiopia, 180 km away from Bahir Dar the capital city of Amhara Regional State. Gondar city has a total area of 192.3Sq.KM.

Study population and sampling

All Adults whose ages between 18 and 65 years old and who are residents of Gondar city were included. Those Critically ill Individuals who couldn’t give information were excluded.

The sample size of the study was calculated using a single population for intention to donate blood and a double population means for predictors. The final sample size of the study was 524 adults.

From a total of six sub-cities of Gondar city, two sub-cities were randomly selected using a simple random sampling technique. Then a systematic sampling technique was employed to select households from each sub-city. The interval value (K) was calculated for selected sub-cities by dividing the total number of households of each selected sub-city to the proportional sample size of the sub-city. The initial household to be interviewed was selected randomly with a lottery method.

Data collection procedure

Data were collected with an interviewer-administered pretested structured questionnaire prepared by the investigator after reviewing different relevant literatures[9, 11–15]. The questionnaire was consists independent variables such as socio-demographic characteristics, knowledge questions, past experience, and theory of planned behavior variables (direct and indirect attitude, direct and indirect subjective norm, direct and indirect perceived behavioral control) and the dependent variable intention.

Measurements

Intention

Intention to donate blood was measured by using three items[12]. “I decided to donate blood in the next three months, “I want to donate blood in the next three months and “I would like to donate blood in the next three months”. Responses ranged "strongly disagree" (1) to "strongly agree" (5). A composite score was summed up by all the items(Table 1). The expected minimum and maximum score was one and five respectively. The internal consistency of the items were (Cronbach’s α = 0.96).

Table 1

Summary of direct and indirect measures of theory of planned behavior variables.

	Item	Scoring	Outcome
Direct measure
I. Attitude(ATT)	5	∑i=15(ATTi)	Direct ATT score
II. Subjective norm(SN)	5	∑i=15(SNi)	Direct SN score
III. Perceived behavioral control(PBC)	5	∑i=15(PBCi)	Direct PBC score
IV. Intention(I)	3	∑i=13(Ii)	Intention score
Indirect measures
I. Behavioral belief(BB)	5	∑i=15(BB*OE)	Indirect ATT score
II. Outcome evaluation(OE)	5
III. Normative belief(NB)	4	∑i=14(NB*MC)	Indirect SN score
IV. Motivation to comply(MC)	4
V. Control belief(CB)	5	∑i=15(CB*PC)	Indirect PBC score
VI. Power of control(PC)	5
VII. Knowledge(Kng)	10	∑i=01(Kngi)	Knowledge score

Attitude

Direct attitude towards blood donation was assessed by five items.” for me donating blood in the next three months is pleasant/unpleasant, bad/good, satisfying/unsatisfying, useful/harmful…… “On five point Likert scale. A composite score of direct attitude was obtained by summing up all the five items. The expected minimum and maximum score was five and twenty five respectively. The internal consistency of direct attitude was (Cronbach’s α = 0.83). Five items were used to measure behavioral belief with responses ranged from “strongly disagree agree”(1) to “strongly agree”(5). Outcome evaluation of blood donation beliefs were measured by asking participants to evaluate the five salient beliefs consequences of blood donation. Each behavioral belief was multiplied by the outcome evaluation to produce a new variable an indirect attitude. A composite score of an indirect attitude was obtained by summing up all the five products of behavioral belief and outcome evaluation.

Subjective norm

A total of five items were used to assess the direct subjective norm. The score ranged from 1 to 5 and had high internal consistency (Cronbach’s α = 0.77). A composite score of the direct subjective norm was obtained by summing up all the five items. The expected minimum and maximum score was five and twenty five respectively. A total of four items were used to assess normative belief and the response ranged from 1 to 5. Each normative belief statement converted into four corresponding motivations to comply with items. Each normative belief was multiplied by the motivation to comply to produce indirect subjective norm. A composite score of the indirect subjective norm was obtained by summing up all the four products of normative belief and motivation to comply.

Perceived behavioral control

Direct perceived behavioral control was assessed by five items. All of them were Likert scale questions. The score ranged from 1 to 5 and had high internal consistency (Cronbach’s α = 0.78). A composite score of direct perceived behavioral control was obtained by summing up all the five items(Table 1). The expected minimum and maximum score was five and twenty five respectively. Five items were used to measure control belief with responses ranged from 1 to 5. Each control belief statement converted into five corresponding power of control items. Each control belief was multiplied by the power of control to produce an indirect perceived behavioral control. A composite score of indirect perceived behavioral control was obtained by summing up all the five products of control belief and power of control.

Knowledge

Knowledge towards blood donation was assessed using ten questions. The questins were developed from reviewing different literatures which had similar demographic characteristics[16-18]. Some of the items were measured as yes or no and others were measured with multiple response options. Some of the items had response option of “don’t know”. For example the question “What is the appropriate age to donate blood?” had response options of “<18, 18–65, >65 and don’t know”. Each response were scored with value of “1” for correct response and for incorrect response given value of “0”. Individuals who respond “don’t know” were considered as incorrect. Knowledge score of each individuals was obtained by summing up all the ten items and the expected score ranged from 0 to 10.

Data processing and analysis

All collected data were entered into EpiData version 3.0 and exported to STATA version14 statistical software for its analysis. Descriptive analysis was used to see frequency distribution, mean and standard deviation. Correlation analysis was done between indirect and direct theory of planned behavior (TPB) variables to see the correlation between them. Multiple Linear regression analysis was computed to test the strength and direction of association between the dependent variable and independent variables. R2 was used for the ability of explanatory variables to explain dependent variables. An unstandardized β coefficient was used to interpret the effect of predictors on the intention to donate blood. The assumption of normality was checked statistically and it was normally distributed. Test of homoscedasticity using white’s test was conducted. All results supported the assumption of homoscedasticity. Linearity assumption was checked using a scatter plot of the standardized residuals versus the predicted values from the regression analysis. Multicollinearity assumptions were tested by the variance inflation factor (VIF) and the value of all variables was below ten. The assumption of an outlier was tested using Cook’s and there was no outlier[19]. Variables with a p-value of less than 0.05 at 95%confidence intervals were considered as statistically significant.

Ethical consideration

Ethical clearance was obtained from the Institutional Review Committee of the institution of Public Health, College of Medicine and Health Sciences, University of Gondar. A letter of permission was obtained from Gondar city administrative health office. After the purpose and objective of the study have been informed, verbal consent obtained from each study participant. All participants were informed that to participate voluntarily and they can withdraw from the study at any time if they were not comfortable about the questionnaire. To keep confidentiality of any information provided by study subjects, the data collection procedure was anonymous.

Results

Socio-demographic characteristics

A total of 515 respondents have participated with a response rate of 98%. Most of them (66.4%) were females and the participants’ age were range from 18 to 65 years. The mean age of participants with standard deviation was (32.25 years ±9.32 years). Nearly 88.3% were orthodox Christian in religion and 80.58 were Amhara in ethnicity (Table 2).

Table 2

Socio-demographic characteristics of Gondar city adults, North West Ethiopia, 2019(N = 515).

Variable	Category	Frequency	Percent
Age	18–30	264	51.3
	31–40	156	30.3
	41–50	72	13.0
	> = 51	23	4.5
Marital status	Single	219	42.6
	Married	215	41.8
	Divorced	62	11.4
	Widow	19	3.7
Educational status	Unable to read and write	60	11.7
	Able to read and write	78	15.2
	Grade1-8	35	6.8
	Grade 9–12	114	22.1
	Diploma	123	23.9
	Degree and above	105	20.4
Ethnicity	Amhara	415	80.6
	Kimant	88	17.1
	Others	12	2.3
Religion	Orthodox Christian	455	88.4
	Muslim	51	9.9
	Others	9	1.8
Occupation	Government employee	157	30.5
	Private employee	122	23.7
	Merchant	52	10.1
	Student	42	8.2
	No job	83	16.1
	Others	59	11.5
Income(Birr /month)	<500	103	20.0
	500–1000	113	22.0
	1001–1500	40	7.8
	> = 1500	259	50.3

Knowledge about blood donation

Respondents were asked ten questions that assess knowledge of blood donation. For each knowledge item scores were summed up to get over all knowledge score, individuals correctly answered the item given value of “1” and for those answered incorrectly valued”0” and then mean and standard deviation were calculated. Accordingly, the mean and standard deviation of knowledge score was 6.23±2.07. More than half (55.53%) of participants correctly knew the appropriate age category of blood donation (18–65 years old), with respect to the amount of blood donated at one time 137(26.6%) knew that it is transfused 350ml to 450 ml and 150(29.13%) knew the minimum weight required to donate blood is 45 kilograms (Table 3).

Table 3

Knowledge of adults on blood donation at Gondar city, North West Ethiopia, 2019(N = 515).

Variable	Category	Correct answer	Incorrect answer
Highly bleed individuals with an accident needs blood	Yes	482(93.6%)	33(6.4%)
	No
Mothers bleed during delivery need blood	Yes	483(93.8%)	32(6.2%)
	No
Patients undergo major surgery need blood	Yes	406(79.0%)	109(21.2%)
	No
Severe anemic patients need blood	Yes	417(81.0%)	98(19.0%)
	No
What is the appropriate age to donate blood	<18	286(55.6%)	229(44.5%)
	18–65
	>65
	Don’t know
Who are eligible to donate blood	Males only	441(85.7%)	74(14.4%)
	Females only
	Both
Amount of blood donated at one time	350-450ml	137(26.6%)	378(73.4%)
	500ml
	200ml
	Don’t know
Duration of blood on the shelf	1 month	128(24.9%)	387(75.1%)
	2 months
	3 months
	>3 months
	Don’t know
Interval of blood donation	Every week	279(54.2%)	236(45.8%)
	Every month
	Every 3 months
	Every 6 months
	Every year
	Don’t know
Minimum weight for blood donation	< 45 kg	150(29.1%)	365(70.9%)
	45kg
	50kg
	55kg
	Don’t know

words/phrases which are written italic are correct answers

Past experience of blood donation

Of the total respondents, 80(15.53%) had ever practiced at least once donate blood in their lifetime. From those 38(47.50%) were donated once, 33(41.25%) had donated twice, 6(7.50%) thrice and 3(3.75%) had donated more than three times. Individuals who didn’t donate blood mention their reasons of those 228(52.41%) had no information when and where blood donated and 42(9.66%) of them mentioned other different reasons such as weight is low than required, not interested to give their blood to other than family. Furthermore, Respondents were asked whether they or their families required a blood and 29(5.63%) of them had required, of those 22(75.86%) had been transfused.

Theory of planned behaviour variables

The mean score of the indirect subjective norm was 50.94±17.82 and mean score of the indirect perceived behavioral control was 49.52± 24.44 (Table 4).

Table 4

Distribution of TPB variables on intention to donate blood of Gondar city adults, North West Ethiopia, 2019(N = 515).

Variable	Mean	Standard deviation	Minimum	Maximum
Direct attitude	18.1	3.5	8	25
Direct subjective norm	17.2	3.6	6	25
Direct PBC	17.4	3.4	8	25
Indirect attitude	65.2	34.6	8	125
Indirect subjective norm	50.9	17.8	7	100
Indirect PBC	49.5	24.4	8	125
Intention	3.0	1.1	3	15

Magnitude of intention

The magnitude of intention was assessed using three items of the five-point Likert scale. The mean intention of respondents was 3.02 with a standard deviation of 1.13. The reliability test of Cronbach’s alpha was (ά = 0.96).

Correlation of theory of planned behavior variables and other variables with intention

All predictors of the intention of theory of planned behavior variables had positively and significantly correlated with intention at a p-value of <0.05. Direct subjective norm had the highest correlation followed by direct perceived behavioral control, direct attitude, past experience of blood donation and indirect subjective norm. Indirect perceived control had the least correlation. All indirect measures positively correlated with their direct measures. Indirect attitudes with direct attitude and indirect subjective norm with direct subjective norm had medium correlation whereas indirect perceived behavioral control with direct perceived behavioral control had a weak correlation[20] (Table 5).

Table 5

Pearson correlation of TPB variables among adults of Gondar city, North West Ethiopia, 2019(N = 515).

Variables	1	2	3	4	5	6	7	8
1. Intention
2. Direct ATT	0.4*
3. Direct SN	0.53*	0.7*
4. Direct PBC	0.46*	0.6*	0.61*
5.Indirect ATT	0.48*	0.65*	0.57*	0.54*
6.Indirect SN	0.27*	0.37*	0.47*	0.44*	0.41*
7.Indirect PBC	0.14*	0.11*	0.12*	0.25*	0.07	0.47*
8. knowledge	0.30*	0.38*	0.35*	0.28*	0.19*	0.31*	0.26*

* = Correlation is significant at 0.05(2 tailed)

Simple linear regression

Prior to the analysis the assumptions of linear regression were checked as mention above in method part. Then Simple linear regression was performed to assess the association of each independent variable with intention to donate blood at 95% confidence interval. Variables which were significant in simple linear regression were entered to multiple linear regression for further statistical significance. Sociodemographic variables (sex, educational status, marital status, income and occupation), knowledge, past experience of blood donation and all direct measures of TPB variables were candidates for multiple linear regression model.

Multiple linear regression

First TPB variables such as direct attitude, direct subjective norm and direct perceived behavioral control were entered to the regression. These variables explain the model 36.5%. Then past experience of blood donation were added to TPB variables and explain the model 40.4%. Finally other external variables (sociodemographic variables and knowledge) were added.

The variance explained by the intention to donate blood from all predictors was 49%. In multiple linear regression variables which found statistically significant at 5% level of significant were direct subjective norm (β = 0.11; CI (0.04, 0.17), direct perceived behavioural control (β = 0.14, CI (0.04, 0.23)), Direct Attitude (β = 0.03; CI (0.01, 0.06) and past behaviour of blood donation (β = 0.3; CI (0.07, 0.51). The standardized regression coefficient suggested that direct subjective norm is by far the most important predictor of intention to donate blood followed by direct perceived behavioral control, direct attitude and past experience of blood donation. The model result showed that previous experience of blood donation affects significantly and positively intention to blood donation. Respondents who had previous experience of blood donation were 0.3 times more intended than those who didn’t have experience provided that other variables are kept constant. Direct subjective norm positively and significantly influence the intention to donate blood. For a score increase of direct subjective norm intention to donate blood increase by score of 0.11 provided that other variables are kept constant. Keeping other variables constant, for a positive score increase of direct perceived behavioral control intention to donate blood increase by score of 0.14. A positive score increase in attitude could result in an increase of intention to donate blood by score of 0.03 provided that other variables kept constant (Table 6).

Table 6

Multiple linear regression of intention to donate blood and its predictors among adults of Gondar city, North West Ethiopia, 2019(N = 515).

Variable		Unstandardized B	Standardized β	95% CI for B
Constant		-4.61		-12.04,2.82
Sex	Female(ref.)
	Male	0.01	0.01	-15, 15
Marital status	Single(ref)
	Married	0.02	0.01	- 0.15, 0.20
	Divorced	0.11	-0.01	-0.19,0.41
	Widowed	0.09	-0.01	-0.36, 0.55
Occupation	No job(ref.)
	Gov’t employee	0.20	-0.04	-0.08, 0.48
	Private employee	0.06	-0.05	-0.18, 0.31
	Merchant	0.31	-0.01	-0.01, 0.63
	Student	0.23	0.01	-0.08, 1.19
Income in ETB	<500(refer)
	500–1000	0.02	0.02	-0.76, 0.81
	1001–1500	-0.78	-0.01	-1.85, 0.28
	>1500	-0.39	0.01	-1.19, 0.41
Knowledge		0.48	0.03	-0.09, 0.18
Experience of blood donation	No(ref)
	Yes	0.30*	0.08	0.07, 0.51
Direct attitude		0.03*	0.10	0.01, 0.06
Direct SN		0.11*	0.50	0.04, 0.17
Direct PBC		0.14*	0.14	0.04, 0.23

*p<0.05, ref. = reference

Here in Fig 1 shows that All of the indirect measures significantly associate with their direct measures and further those direct measures (attitude, subjective norm and perceived behavioural control) had significantly predict blood donation intention. All indirect measures of TBP variables had significant correlation each other. Direct subjective best explained intention (R2 = 34), direct perceived behavioural control explained 27% (R2 = 0.27) and direct attitude explained 25% (R2 = 0.25). Those studies might be familiar with Likert scale questions so that they could easily understand.

Fig 1

Standardized path coefficient of theory of planned behavior variables (all significant at p<0.05).

IATT = indirect Attitude; ISN = indirect Subjective norm; IPBC = indirect perceived behavioral control.

Discussion

In this study, the intention of blood donation and its predictors among adults were assessed using the theory of planned behavior. Subjective norm, Attitude, perceived behavioral control from the theory of planned behavior variables and past experience of blood donation were predictors of intention to donate blood in the next three months. The model explained 49% of the variance in intention to donate blood. This finding is lower than the study conducted in Ireland [9] and Pakistan [21]. This difference may be due to socio-economic and socio-cultural variation, respondents in those studies might be familiar with Likert scale questions so that they could easily understand it [22].

The present study revealed that external variables such as all socio demographic variables and knowledge had no significant effect on intention to donate blood in the next three months. This means prediction of intention to donate blood don’t vary among individuals having different sociodemographic characteristics and knowledge level towards blood donation.

In this study, the mean intention to donate blood in the next three months was neutral. This finding is consistent with a study conducted in Mekelle, Dire Dawa and Israel[10, 23, 24].

The result of our finding revealed that direct subjective norm is a predictor of intention to donate blood. This is comparable with studies conducted in China and in Ireland[9, 25]. This suggests that decisions made in this context do not only concern the respondents but also families, friends, relatives, and health professionals. Thus, interventions to improve blood donation practice should also target those important others (families, friends, relatives, and health professionals) as a whole rather than focusing only on the individual who are eligible to donate blood donation. If their important others are engaged in blood donation practice, eligible individuals are more likely to participate in this practice.

The current study also reported that direct perceived behavioral control is the predictor of intention to donate blood in the next three months. This finding is supported by a study conducted in Ireland [9] and a study in Pakistan [21]. This is because those individuals who perceived that donation blood in the following three months is easy and those individuals who are confident enough to donate were more likely to donate blood. This suggests that encouraging individuals to aim for donating blood should involve consideration of factors that is under their control. That means those individuals who able to control the fear of pain from the needle, control fear of fainting after donation, control fear of becoming anemic following giving blood and control fear of being susceptible to certain health problems after donation so that they may lead to increased intention to donate blood. These results support Ajzen’s theoretical assumptions; the more individuals have a high degree of control over factors that facilitate or prevent them to donate blood; the greater will be their intention to donate blood[12].

This study prevailed that direct attitude was a predictor of intention to donate blood in the next three months. This is consistent with studies conducted in China, Pakistan and Botswana[21, 25, 26]. This implies that health education interventions should be given which targeted on creating favourable attitude towards blood donation. Those individuals who believed that blood donation could reduce death of mothers, save life of anemic patients and gives internal satisfaction were more likely to had favourable attitude and then more intended to donate blood.

Conclusion

This study revealed that past experience of blood donation, direct subjective norm, direct perceived behavioral control, and direct Attitude predict the intention of blood donation in the next three months. All indirect measures were significantly and positively correlated with their respective direct measures. None the external variables such as socio-demographic factors and knowledge were significant predictors of intention to donate blood.

29 Aug 2019

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3 Oct 2019

PONE-D-19-22717

INTENTION TO DONATE BLOOD AND ITS PREDICTORS AMONG ADULTS OF GONDAR CITY: USING THEORY OF PLANNED BEHAVIOR

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Reviewer #1: The paper looks at understanding the motivations of people to donate blood in two Gondar sub cities, this is fine, but the same does not necessarily seem to reflect the demographic population of Ethiopia and this at least needs to be mentioned.

I am not sure why the authors use regression analysis as this does not allow more complex relationships to be consider and also assumes each variable varies independent of others. Thus Structural equation modelling (which is often used when undertaking research using TPB) would strengthen the analysis.

The abstract also mentions that the mean score of giving is lower, but this does not seem to be the focus as the question is how do these other TPB variables influence this intention. The conclusion in the abstract needs to be more than state the results.

The intro seems to suggest that donation is the only recruitment method and in some African countries people are paid and thus it is not a generous behaviour.

I found the introduction and other choppy with multiple single sentence paragraphs. These are all fine, but the authors might craft a story around the issues.

For the measures I do think they need to identify the specific scales that were used. These are not referenced and I am not sure who measures were used. This is needed. There is no description of the test of the knowledge measure and how did they make sure their measure was appropriate? For the first question on this it reads as if people could select multiple answers as the sum is greater than the sample number? What did they do with the don’t know respondents are these correct or incorrect?

It is unclear if they ran a factor analysis to assess the measures or just Cronbach’s alphas? Some constructs don’t mention the alphas.

The demographics are fine, but they need to comment if this is reflective of the population.

Table 4 does not include knowledge?

The regression included demographics, which is fine, but thy cold explain this and why it was done. I am not sure why they did not use knowledge as a continuous variable? They also mentioned that they include past donation behaviour and this does not seem to be included and should.

I personally prefer more complex models rather than regression or at least some assessment of interaction effects as it is assumed the variables do not impact on each other.

The discussion discuses a range of factors such as fear of needles and I am not sure where this was included in the survey. I do think that there should be a brief discussion of the blood donation process in Ethiopia as it could also be that it I shard to access blood donation locations, which could then explain these results. I just don’t know if it is an issue in the discussion as it is presented.

The statement “Most individual’s intention to donate blood in the next three months were below the mean intention.” Needs to be rewritten as I think they mean it was below the scale midpoint. Can most people be below average?

Reviewer #2: Methods part, may need more explanation how several variables were measured. Furthermore, discussion part there is a need to focus of discussing the findings rather than repeating the result which are already interpreted on result section

Reviewer #3: The manuscript need English editing. The paper needs modification for methodology and results. Theory of planned behavior should be described in detail. The model used should also be explained in methods. Please see attached comments for revision.

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: Yes: Bushra Moiz

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Submitted filename: Reviews-PlosOne.docx

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Submitted filename: PONE D 19 22717 review.docx

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6 Nov 2019

we have attached the response to each reviews.

Submitted filename: Point by point responses for reviewers TPB.docx

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26 Nov 2019

PONE-D-19-22717R1

INTENTION TO DONATE BLOOD AND ITS PREDICTORS AMONG ADULTS OF GONDAR CITY: USING THEORY OF PLANNED BEHAVIOR

PLOS ONE

Dear Mr Kassie,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

The manuscript has been considerably improved for this version. Both reviewers agree on its value and pertinence, but some further changes are required. You will also find a sanitized copy attached to the comments, containing some additional queries and suggestions.

Please put especial attention to those comments related to the discussion and interpretation of the findings (also, all the conclusions should be properly supported by the data), and their practical implications. Also, be careful with the technical issues referred by our reviewers.

As a particular comment, I would ask the authors to de-capitalize the title of the manuscript.

We would appreciate receiving your revised manuscript by Jan 10 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

Kind regards,

Sergio A. Useche, Ph.D.

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Partly

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: I Don't Know

Reviewer #2: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: No

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: There are still some expression issues in the new sections. I cannot identify all of these but the paper needs to be professional copy edited.

For example:

“The amount of unit of blood needed by blood banks and actual collected unit of blood is not compatible. Should be that there is a deficit between the amount of blood needed and collected.

“In developing countries like Ethiopia the most source of blood is obtained from generous individuals, and most of it is collected through campaign because there is no trend of people going and providing blood in blood banks.” I am not sure what this is saying?

Therefore this study assessed the factors within the theory of planned behaviour which determine influence individuals to donate blood; including like their attitude, influence of other individuals (subjective norm), presence of facilitating and hindering factors, individuals level of perceived behavioural control and their previous experience of donation to future.

The elicitation study was conducted, to explore relevant salient behavioral beliefs, normative belief and perceived behavioural control.

five and twenty five respectively. (Other times they us 5 to 25)

Knowledge: knowledge towards blood donation was assessed using ten questions which were previously used items in similar research which had similar demographic characteristics.

The test for outlier was assessed using Cook's and there was no outlier. (Is this a method or a measure and should be clearer also do they need a reference?)

The authors need to indicate what do not know means for the knowledge scale, in the manuscript, not just in the response document (this is also not discussed in the knowledge section and there may be no don’t know category). Knowledge is also not described in Table 1. I am not sure you need to explain response for individual questions, as this appears in Table 3.

Correlation does not look at the relationship (i.e. inferring causality). Thus this might need to be rephrased.

In the paper it needs to explain that the sample is representative of the population. I do think this is odd given the composition (i.e. the population is not 66% female and a very high orthodox Christian sample). In the mention of the religion, it should read Christian orthodox means as there are many religions that refer to orthodox?

I want to thank the authors for the additions of the models, but I am not sure how these relate to multiple regression in Table 6? If this is a SEM model, then it needs to be better explained and discussed. If they don’t do this then they should cut the diagram.

The section labelled strength and limitation is an odd title?

Reviewer #2: Some of the comments were not addressed adequately, especially on results and discussion.There is need for the author to clearly and correctly interpret the results. Discussion part, he/she may need to familiarise oneself with the best way of discussing the findings .

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Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

Submitted filename: Reviews-PlosOne (1).docx

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12 Jan 2020

dear Editor/reviewers, we, authors would like express our heart felt gratitude for giving us your comments and suggestions. we respond point by point for each raised concerns. so you can see the attached respones.

thanks alot

Submitted filename: Point by point response - Copy.docx

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28 Jan 2020

Intention to donate blood and its predictors among adults of Gondar city: using theory of planned behavior

PONE-D-19-22717R2

Dear Dr. Kassie,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication.

Shortly after the formal acceptance letter is sent, an invoice for payment will follow. To ensure an efficient production and billing process, please log into Editorial Manager at https://www.editorialmanager.com/pone/, click the "Update My Information" link at the top of the page, and update your user information. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, you must inform our press team as soon as possible and no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

With kind regards,

Sergio A. Useche, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: No

Reviewer #2: (No Response)

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: (No Response)

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: (No Response)

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: (No Response)

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The authors have significantly improved the expression.

A few minor issues still arise:

“knowledge towards blood donation was assessed using ten questions which were previously used items in similar studies believed to be having similar demographic characteristics[16-18].”

Nearly 88.3% 212 were orthodox in religion and 80.58 were Amhara in ethnicity (Table 2). What type of orthodox?

Reviewer #2: (No Response)

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: No

Reviewer #2: Yes: Wilhellmuss Mauka

5 Feb 2020

PONE-D-19-22717R2

Intention to donate blood and its predictors among adults of Gondar city: using theory of planned behavior

Dear Dr. Kassie:

I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please notify them about your upcoming paper at this point, to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

For any other questions or concerns, please email plosone@plos.org.

Thank you for submitting your work to PLOS ONE.

With kind regards,

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on behalf of

Dr. Sergio A. Useche

Academic Editor

PLOS ONE