Efficacy of contrasting background on a drug label: A prospective, randomized study.

BACKGROUND AND AIMS: Medication error can occur due to fault at any level starting from manufacturing until the administration to the patient. It can be difficult to read the drug name and other information from an ampoule, if there is poor contrast between the font color and background of the ampoule. Primary aim of this study was to evaluate the efficacy of the contrast color on the ampoule's label.
MATERIAL AND METHODS: The study was conducted in a randomized blinded manner at a tertiary level trauma center. One hundred and eight resident doctors participated in the study. All the participants were divided into two groups after randomization. Group A was given the original drug ampoule while the modified ampoule with contrast was given to Group B. Total time in reading the ampoule and difficulty in reading (DR) scoring were noted for each participant. Another scoring regarding correct reading of ampoule was also noted and compared. STATISTICAL ANALYSIS: Student's t-test and Mann-Whitney test were used accordingly and P < 0.05 was considered as significant.
RESULTS: It was found that mean time taken in reading the original ampoule was more compared to modified ampoule (11.64 ± 1.48 vs. 9.48 ± 1.62 seconds P < 0.05). DR score was also higher in Group A (P < 0.05) and correct reading score was more in Group B (P < 0.05).
CONCLUSION: The labels on drug ampoules or vials should always have a contrasting background. This may reduce medication error and improve patient safety.

RCT Entities:   Population Interventions Outcomes

Introduction

Medication error is one of the leading causes of morbidity and mortality in hospitalized patients, and it is reported to be the seventh most common cause of death.[1] A medication error can be defined as “a failure in the treatment process that leads to, or has the potential to lead to harm the patient.” The treatment process also includes the manufacturing or compounding, prescribing, transcribing, dispensing, and administration of a drug and the subsequent monitoring of its effects.[2] The practice of Anesthesiology requires the administration of a wide variety of potent medications. Drug errors represented 4% claims in the American Society of Anesthesiologists (ASA) closed claim project report in 2003. American Society for Testing and Material (ASTM) International describes the standards of printing the label of drug ampoules according to which the label presents the generic name of the drug, the total amount per total volume and the drug concentration in black text on a white background.[3] In addition; the drug's proprietary name, manufacturer, lot number, date of manufacturing and expiry date should also be included on the label. Maximum contrast between the text and the background should be provided by high contrast color combinations as specified in ASTM international standard, which also minimize the impact of color blindness. Despite these standards, some manufacturers still use ceramic print on clear glass, which has no contrasting background. A label may be virtually illegible depending on the color of print, the background and lighting conditions.

In this study, our aim was to find out the effect of contrasting background in reading the drug ampoules correctly. On Medline search, we couldn’t find any randomized trial evaluating the efficacy of ASTM standards for drug labeling.

Material and Methods

The study was conducted from September 2011 to November 2011 at our center, which is a tertiary care level hospital. Resident doctors of different specialties working in our hospital during this period were enrolled in the study. The resident doctors who had not undergone acuity of vision test in last 1-year were excluded from the study. All resident doctors were randomly allocated in two groups. Randomization was done using computer generated tables of random numbers. The original ampoule without any contrasting background and the modified ampoule with white background and black font were given to Group A and Group B respectively. The modified ampoule was simulated to have a contrasting background by removing the transparent label and pasting white paper beneath the label [Figure 1]. The study was conducted in a single-blinded manner. Each participant was called in a well-illuminated room and an ampoule was given randomly. They were instructed to read the batch number, date of manufacturing and date of expiry. A duty nurse was instructed to note down the time taken in reading these three variables and to check whether the participant had read it correctly. The duty nurse was not involved in the study and was unaware of the objective of the study. The time taken to read each variable was noted, and one point was given for each correct reading. If the participant had read all three variables correctly, three points were given to him. The participants were also instructed to give a difficult to read (DR) scoring ranging from 1 to 10 on a scale for difficulty in reading the ampoule, where 1 stands for very easy to read and 10 for very difficult to read. We used only two ampoules in the study, both the ampoules were having same batch number, date of manufacturing and date of expiry. Other variables like the cost of the drug, content, amount per ml might have been known to the participants and hence were not included in our study.

Figure 1

The modified ampoule with contrast background and the original ampoule with the noncontrasting background

The sample size was calculated presuming that the time taken in reading drug ampoule would differ by 3 s in both the groups and within group standard deviation would be 3 (α = 0.05 and power = 0.95); hence, we required at least 27 participants in each group. The time difference of 3 s was calculated from the pilot study results done in 20 participants. All resident doctors in that particular period were included in the study. Chi-square test and Student's t-test were used to analyze categorical variables and to analyze the time taken in reading the ampoules. DR and points scored in both the groups were analyzed by Mann–Whitney test. SPSS 16.0 (SPSS, Chicago, IL, USA) was used for statistical analysis; P < 0.05 was considered as significant.

Results

One hundred and eight resident doctors participated in the study. There was no difference between both the groups regarding age, sex and specialty of resident doctors [P > 0.05, Table 1]. The time taken in reading the ampoule was significantly less in Group B as compared to Group A [P < 0.01, Figure 2a]. Group A participants read the variable wrong at many occasions compared to Group B, the median score was higher in Group B [P < 0.05, Figure 2b]. Difficulty in reading the ampoule was significantly less in Group B compared to Group A [P < 0.05, Figure 2c].

Table 1

Demographic data of both the groups

Figure 2

(a) Mean time in seconds taken in reading by both groups, (b) score of correct reading, (c) difficult in reading score *indicates P < 0.05

Discussion

Our study shows that contrasting background on drug ampoule's label improves the legibility and decreases reading error. The mean time in reading these ampoules was significantly less. Apart from contrasting background, other factors affecting the ability to read an ampoule include the size, boldness of the font, the visual acuity, power of accommodation of the reader and illumination of the surrounding. To avoid such errors in our study, we took two similar ampoules and were read by participants in similar illumination. The participants were unable to read the ampoule correctly in Group A and few participants could read only two components correctly. Although we took three variables printed in bold letters, it was difficult to read without contrasting background. The impact of contrasting background can be assessed by reading batch number and date of manufacturing, although, it does not have much clinical significance.

Medication errors are quite common despite newer methods and technology. These errors have been estimated to account for 7000 deaths in 1993 in United States.[4] In a previous survey conducted in New Zealand, 89% of the participants had admitted that they had encountered drug error at some stage during their career, and 12.5% had harmed the patients.[5] In a review from Australian incident monitoring study, out of 896 reports, 187 (20.8%) were due to wrong drug ampoule selection or labeling error.[6] In a case reported by Orser and Oxorn, adrenaline was administered to the patient while reversing the neuromuscular blockade instead of glycopyrrolate and the patient developed pulseless ventricular tachycardia. In this case, both the ampoules looked similar, and both were having printing without any contrast background.[7] In a previous report, it was found that all ampoules with a clear background had poor contrast and were difficult to read.[8]

American Society for Testing and Material had given certain guidelines regarding labeling on ampoules in 2004, and they were approved and accepted by ASA. The primary concern in the design of the label should be patient safety. Drug's generic name, concentration and volume should be the most important items on the label, and it should be prominent. In addition, other information like batch number, date of manufacturing and date of expiry should also be mentioned. The font on the label should be defined in such a manner that the recognition of the drug name and concentration should be easy. The size of the generic name and dose should be 1.5 mm or more in a 2 ml ampoule and >2.5 mm in >2 ml ampoule. There should be maximum contrast between the text and the background color. Different combinations of text and background colors have also been mentioned in section 6.3.1 of ASTM International standard D6398 [Table 2]. Commonly used drugs in anesthesia were divided into nine classes and different color coding was described for each class by ASTM international standards D4774. In these drugs, standardization of the color of the container's top, label border and any other colored area excluding the background [Table 3] have been recommended. Bar coding should be there on the drug vial or ampoule, which includes drug's generic name, concentration and volume of drug, and it should not interfere with the label's legibility.

Table 2

Contrasting background combinations as recommended by ASTM international standard

Table 3

Nine classes of drugs with their recommended color

A limitation of our study was that only doctors participated in this study. Since nurses are more involved in wards for drug administration, their involvement may give a better result. Another limitation of this study was that the study was done in a simulated environment; results may vary in wards during busy hours. In this study, we tested only one color combination; hence, further studies should be done to evaluate the other combinations as well. To summarize, the labels on drug ampoules or vials should always have a contrasting background in view of patient safety, and it may reduce medication errors in the future.