| Literature DB >> 25038830 |
Judith A Hahn1, Robin Fatch, Rhoda K Wanyenze, Steven Baveewo, Moses R Kamya, David R Bangsberg, Thomas J Coates.
Abstract
BACKGROUND: Alcohol use has a detrimental impact on the HIV epidemic, especially in sub-Saharan Africa. HIV counseling and testing (HCT) may provide a contact opportunity to intervene with hazardous alcohol use; however, little is known about how alcohol consumption changes following HCT.Entities:
Mesh:
Year: 2014 PMID: 25038830 PMCID: PMC4223423 DOI: 10.1186/1471-2334-14-403
Source DB: PubMed Journal: BMC Infect Dis ISSN: 1471-2334 Impact factor: 3.090
Baseline demographic and behavioral characteristics of participants undergoing HCT in Kampala, Uganda
| | | ||||
|---|---|---|---|---|---|
| | |||||
| | | | | | |
| Male | 879 (42.8) | 351 (38.9) | 222 (40.6) | 165 (46.9) | 108 (57.1) |
| Female | 1177 (57.3) | 551 (61.1) | 325 (59.4) | 187 (53.1) | 81 (42.9) |
| | | | | | |
| 18–25 | 580 (28.2) | 321 (35.6) | 130 (23.8) | 86 (24.4) | 26 (13.8) |
| 26–35 | 852 (41.4) | 353 (39.1) | 212 (38.8) | 162 (46.0) | 94 (49.7) |
| >35 | 624 (30.4) | 228 (25.3) | 205 (37.5) | 104 (29.6) | 69 (36.5) |
| | | | | | |
| Primary education or less | 1043 (50.8) | 439 (48.7) | 278 (50.9) | 191 (54.3) | 102 (54.0) |
| More than primary education | 1011 (49.2) | 462 (51.3) | 268 (49.1) | 161 (45.7) | 87 (46.0) |
| | | | | | |
| Laborer | 668 (32.5) | 285 (31.6) | 186 (34.0) | 119 (33.8) | 54 (28.6) |
| Business/Sales/Technical | 901 (43.8) | 388 (43.1) | 240 (43.9) | 151 (42.9) | 91 (48.2) |
| Other | 486 (23.7) | 228 (25.3) | 121 (22.1) | 82 (23.3) | 44 (23.3) |
| | | | | | |
| Protestant | 629 (30.6) | 217 (24.1) | 161 (29.4) | 135 (38.4) | 88 (46.6) |
| Catholic | 651 (31.7) | 198 (22.0) | 176 (32.2) | 169 (48.0) | 76 (40.2) |
| Moslem | 398 (19.4) | 283 (31.4) | 64 (11.7) | 30 (8.5) | 17 (9.0) |
| Saved/Pentecostal/Other | 378 (18.4) | 204 (22.6) | 146 (26.7) | 18 (5.1) | 8 (4.2) |
| | | | | | |
| Married | 866 (42.1) | 370 (41.0) | 212 (38.8) | 159 (45.2) | 92 (48.7) |
| Married in the past | 656 (31.9) | 248 (27.5) | 208 (38.1) | 116 (33.0) | 65 (34.4) |
| Never married | 533 (25.9) | 284 (31.5) | 126 (23.1) | 77 (21.9) | 32 (16.9) |
| | | | | | |
| Low | 921 (45.0) | 411 (45.7) | 246 (45.2) | 144 (40.9) | 96 (50.8) |
| Medium | 807 (39.4) | 346 (38.4) | 207 (38.1) | 155 (44.0) | 72 (38.1) |
| High | 321 (15.7) | 143 (15.9) | 91 (16.7) | 53 (15.1) | 21 (11.1) |
| | | | | | |
| Sometimes/Often (>2 times/month) | 295 (14.6) | 103 (11.6) | 108 (20.1) | 30 (8.6) | 34 (18.7) |
| Seldom (1–2 times/month) | 200 (9.9) | 66 (7.5) | 61 (11.4) | 39 (11.2) | 28 (15.4) |
| Never | 1522 (75.5) | 717 (80.9) | 368 (68.5) | 280 (80.2) | 120 (65.9) |
| | | | | | |
| Strong support | 274 (13.9) | 107 (12.2) | 81 (15.8) | 36 (10.4) | 35 (19.7) |
| Moderate support | 1311 (66.7) | 628 (71.9) | 325 (63.4) | 254 (73.6) | 86 (48.3) |
| Poor support | 380 (19.3) | 139 (15.9) | 107 (20.9) | 55 (15.9) | 57 (32.0) |
| | | | | | |
| Inpatient wards | 400 (19.5) | 181 (20.1) | 106 (19.4) | 72 (20.5) | 33 (17.5) |
| Outpatient clinics | 1395 (67.9) | 608 (67.4) | 378 (69.1) | 222 (63.1) | 138 (73.0) |
| Emergency/casualty wards | 261 (12.7) | 113 (12.5) | 63 (11.5) | 58 (16.5) | 18 (9.5) |
| | | | | | |
| AIDS symptoms/concern about current illness | 652 (31.7) | 241 (26.7) | 201 (36.8) | 117 (33.2) | 70 (37.0) |
| Just wanted to know/plan for future | 1312 (63.8) | 624 (69.2) | 320 (58.5) | 225 (63.9) | 105 (55.6) |
| Other | 92 (4.5) | 37 (4.1) | 26 (4.8) | 10 (2.8) | 14 (7.4) |
| | | | | | |
| None | 1671 (82.0) | 805 (89.4) | 439 (81.5) | 276 (79.5) | 108 (57.8) |
| Any | 367 (18.0) | 95 (10.6) | 100 (15.6) | 71 (20.5) | 79 (42.3) |
| | | | | | |
| Never | 902 (43.9) | 902 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
| >5 years ago | 191 (9.3) | 0 (0.0) | 191 (34.9) | 0 (0.0) | 0 (0.0) |
| 1–5 years ago | 141 (6.9) | 0 (0.0) | 141 (25.8) | 0 (0.0) | 0 (0.0) |
| 3 months – 1 year ago | 215 (10.5) | 0 (0.0) | 215 (39.3) | 0 (0.0) | 0 (0.0) |
| Prior 3 months | 607 (29.5) | 0 (0.0) | 0 (0.0) | 352 (100.0) | 189 (100.0) |
| 0 (0–1) | | | | | |
| | | | | | |
| HIV Negative | 1058 (51.5) | 529 (58.7) | 250 (45.7) | 176 (50.0) | 71 (37.6) |
| HIV Positive | 998 (48.5) | 373 (41.4) | 297 (54.3) | 176 (50.0) | 118 (62.4) |
| | | | | | |
| <200 | 359 (36.1) | 139 (37.3) | 122 (41.4) | 53 (30.1) | 35 (29.9) |
| 200–349 | 233 (23.4) | 85 (22.8) | 66 (22.4) | 44 (25.0) | 29 (24.8) |
| 350–499 | 202 (20.3) | 74 (19.8) | 60 (20.3) | 34 (19.3) | 26 (22.2) |
| > = 500 | 200 (20.1) | 75 (20.1) | 47 (15.9) | 45 (25.6) | 27 (23.1) |
*n = 66 current drinkers were unable to be classified as hazardous or non-hazardous drinkers.
Multinomial logistic regression of past, current non-hazardous, and current hazardous drinking status at baseline compared to lifetime abstaining
| | ||||||
|---|---|---|---|---|---|---|
| | | | | | | |
| Female | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Male | 1.07 (0.86, 1.33) | 1.25 (0.98, 1.60) | 1.40 (1.10, 1.77) | 1.57 (1.19, 2.07) | 2.10 (1.52, 2.89) | 2.86 (1.96, 4.16) |
| | | | | | | |
| 18–25 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| 26–35 | 1.48 (1.14, 1.93) | 1.28 (0.95, 1.73) | 1.69 (1.27, 2.25) | 1.42 (1.01, 1.99) | 3.23 (2.05, 5.08) | 2.62 (1.53, 4.50) |
| >35 | 2.22 (1.68, 2.93) | 1.94 (1.39, 2.71) | 1.66 (1.21, 2.27) | 1.33 (0.89, 1.98) | 3.62 (2.25, 5.84) | 2.83 (1.55, 5.18) |
| | | | | | | |
| Primary education or less | 1.00 | - | 1.00 | - | 1.00 | - |
| More than primary education | 0.92 (0.74, 1.13) | | 0.82 (0.65, 1.05) | | 0.81 (0.59, 1.12) | |
| | | | | | | |
| Laborer | 1.00 | - | 1.00 | - | 1.00 | - |
| Business/sales/technical | 0.95 (0.74, 1.21) | | 0.93 (0.71, 1.22) | | 1.24 (0.86, 1.79) | |
| Other | 0.81 (0.61, 1.08) | | 0.81 (0.59, 1.12) | | 1.01 (0.65, 1.55) | |
| | | | | | | |
| Protestant | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Catholic | 1.20 (0.90, 1.60) | 1.19 (0.88, 1.60) | 1.39 (1.04, 1.85) | 1.35 (1.01, 1.81) | 0.92 (0.64, 1.32) | 0.84 (0.57, 1.24) |
| Moslem | 0.30 (0.22, 0.43) | 0.32 (0.23, 0.45) | 0.16 (0.11, 0.25) | 0.17 (0.11, 0.26) | 0.14 (0.08, 0.24) | 0.16 (0.09, 0.30) |
| Saved/Pentecostal/Other | 0.96 (0.72, 1.29) | 1.08 (0.79, 1.47) | 0.14 (0.08, 0.23) | 0.15 (0.09, 0.24) | 0.09 (0.04, 0.19) | 0.12 (0.05, 0.25) |
| | | | | | | |
| Married | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Previously married | 1.47 (1.14, 1.88) | 1.44 (1.09, 1.90) | 1.05 (0.80, 1.39) | 1.19 (0.87, 1.64) | 1.05 (0.73, 1.49) | 1.51 (1.00, 2.28) |
| Never married | 0.77 (0.59, 1.01) | 0.98 (0.72, 1.35) | 0.63 (0.47, 0.85) | 0.72 (0.50, 1.04) | 0.44 (0.28, 0.68) | 0.83 (0.48, 1.44) |
| | | | | | | |
| Low | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Medium | 1.00 (0.79, 1.26) | 1.18 (0.91, 1.52) | 1.30 (1.01, 1.69) | 1.48 (1.11, 1.96) | 0.89 (0.64, 1.24) | 1.22 (0.84, 1.78) |
| High | 1.06 (0.78, 1.44) | 1.21 (0.87, 1.68) | 1.13 (0.80, 1.61) | 1.31 (0.89, 1.91) | 0.64 (0.39, 1.07) | 0.75 (0.43, 1.29) |
| | | | | | | |
| Sometimes/Often (>2 times/month) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Seldom (1–2 times/month) | 0.90 (0.58, 1.39) | 0.82 (0.52, 1.31) | 1.48 (0.88, 2.50) | 1.32 (0.75, 2.29) | 1.19 (0.66, 2.12) | 1.32 (0.68, 2.54) |
| Never | 0.49 (0.36, 0.66) | 0.59 (0.42, 0.82) | 1.00 (0.68, 1.46) | 1.13 (0.75, 1.70) | 0.45 (0.30, 0.69) | 0.80 (0.49, 1.32) |
| | | | | | | |
| Strong support | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Moderate support | 0.69 (0.50, 0.95) | 0.73 (0.52, 1.02) | 0.97 (0.67, 1.40) | 1.04 (0.70, 1.54) | 0.40 (0.26, 0.62) | 0.52 (0.32, 0.84) |
| Poor support | 1.03 (0.70, 1.52) | 0.96 (0.64, 1.46) | 1.14 (0.72, 1.82) | 1.37 (0.84, 2.24) | 1.27 (0.78, 2.06) | 1.49 (0.84, 2.63) |
| | | | | | | |
| None | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Any | 1.92 (1.42, 2.60) | 1.80 (1.29, 2.50) | 2.32 (1.68, 3.21) | 1.95 (1.36, 2.79) | 6.24 (4.33, 8.99) | 5.74 (3.80, 8.67) |
| | | | | | | |
| Inpatient wards | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Outpatient clinics | 1.06 (0.81, 1.39) | 1.09 (0.81, 1.46) | 1.00 (0.74, 1.36) | 1.07 (0.77, 1.48) | 1.25 (0.83, 1.89) | 1.63 (1.03, 2.57) |
| Emergency/casualty wards | 0.95 (0.64, 1.41) | 0.84 (0.56, 1.26) | 1.35 (0.90, 2.03) | 1.34 (0.87, 2.08) | 0.88 (0.47, 1.62) | 1.01 (0.52, 1.98) |
| | | | | | | |
| Just wanted to know/plan for future | 1.00 | - | 1.00 | - | 1.00 | - |
| AIDS symptoms/concern about current illness | 1.63 (1.29, 2.05) | | 1.39 (1.08, 1.80) | | 1.67 (1.20, 2.34) | |
| Other | 1.37 (0.82, 2.30) | | 0.92 (0.48, 1.75) | | 2.25 (1.18, 4.30) | |
| | | | | | | |
| HIV negative | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| HIV positive | 1.68 (1.36, 2.09) | 1.49 (1.17, 1.88) | 1.42 (1.12, 1.80) | 1.15 (0.88, 1.51) | 2.34 (1.70, 3.22) | 1.88 (1.30, 2.73) |
RRR: Relative risk ratio.
CI: Confidence interval.
Figure 1Hazardous and non-hazardous drinking at study visits following HIV counseling and testing (HCT), among current drinkers at baseline, by HIV status. 1a. 294 HIV infected drinkers. 1b. 247 HIV negative drinkers.
Multinomial logistic regression of non-hazardous and hazardous drinking compared to no current drinking in the year following HCT, among baseline drinkers
| | ||||
|---|---|---|---|---|
| | | | | |
| Female | 1.00 | 1.00 | 1.00 | 1.00 |
| Male | 1.95 (1.50, 2.53) | 1.81 (1.39, 2.35) | 2.07 (1.43, 2.99) | 1.83 (1.26, 2.65) |
| | | | | |
| 18–25 | 1.00 | - | 1.00 | - |
| 26–35 | 0.94 (0.67, 1.32) | | 0.94 (0.59, 1.51) | |
| >35 | 1.15 (0.80, 1.66) | | 1.11 (0.67, 1.84) | |
| | | | | |
| Primary education or less | 1.00 | - | 1.00 | - |
| More than primary education | 0.97 (0.75, 1.26) | | 1.37 (0.95, 1.95) | |
| | | | | |
| Laborer | 1.00 | - | 1.00 | - |
| Business/sales/technical | 0.91 (0.68, 1.22) | | 1.37 (0.89, 2.10) | |
| Other | 0.94 (0.66, 1.33) | | 1.32 (0.78, 2.25) | |
| | | | | |
| Protestant | 1.00 | - | 1.00 | - |
| Catholic | 0.96 (0.73, 1.27) | | 1.00 (0.68, 1.47) | |
| Moslem | 0.84 (0.52, 1.38) | | 0.89 (0.46, 1.74) | |
| Saved/Pentecostal/Other | 0.58 (0.28, 1.21) | | 0.82 (0.36, 1.90) | |
| | | | | |
| Married | 1.00 | - | 1.00 | - |
| Previously married | 0.69 (0.51, 0.92) | | 0.69 (0.45, 1.04) | |
| Never married | 0.84 (0.59, 1.20) | | 1.04 (0.65, 1.66) | |
| | | | | |
| Low | 1.00 | - | 1.00 | - |
| Medium | 0.92 (0.70, 1.22) | | 1.07 (0.73, 1.57) | |
| High | 1.09 (0.72, 1.65) | | 1.20 (0.68, 2.13) | |
| | | | | |
| Sometimes/Often (>2 times/month) | 1.00 | - | 1.00 | - |
| Seldom (1–2 times/month) | 0.93 (0.56, 1.54) | | 1.24 (0.61, 2.50) | |
| Never | 0.97 (0.66, 1.41) | | 1.13 (0.66, 1.93) | |
| | | | | |
| Strong support | 1.00 | - | 1.00 | - |
| Moderate support | 0.86 (0.60, 1.23) | | 0.89 (0.52, 1.52) | |
| Poor support | 0.96 (0.63, 1.48) | | 1.03 (0.56, 1.89) | |
| | | | | |
| No | 1.00 | 1.00 | 1.00 | 1.00 |
| Yes | 1.60 (1.21, 2.12) | 1.72 (1.29, 2.29) | 2.40 (1.65, 3.51) | 2.68 (1.81, 3.96) |
| | | | | |
| None | 1.00 | - | 1.00 | - |
| Any | 1.22 (0.91, 1.64) | | 1.48 (1.01, 2.16) | |
| | | | | |
| Inpatient wards | 1.00 | - | 1.00 | - |
| Outpatient clinics | 1.02 (0.71, 1.46) | | 0.90 (0.56, 1.44) | |
| Emergency/casualty wards | 0.67 (0.41, 1.10) | | 0.41 (0.20, 0.83) | |
| | | | | |
| Just wanted to know/plan for future | 1.00 | - | 1.00 | - |
| AIDS symptoms/concern about current illness | 0.85 (0.64, 1.12) | | 0.88 (0.59, 1.32) | |
| Other | 1.06 (0.62, 1.82) | | 1.44 (0.64, 3.26) | |
| | | | | |
| HIV negative | 1.00 | 1.00 | 1.00 | 1.00 |
| HIV positive | 0.52 (0.40, 0.68) | 0.49 (0.37, 0.65) | 0.45 (0.31, 0.65) | 0.40 (0.27, 0.58) |
| | | | | |
| Abbreviated HCT | 1.00 | - | 1.00 | - |
| Traditional HCT | 1.01 (0.77, 1.31) | | 0.86 (0.60, 1.23) | |
| | | | | |
| 3 months | 1.00 | 1.00 | 1.00 | 1.00 |
| 6 months | 1.06 (0.83, 1.34) | 1.05 (0.82, 1.35) | 0.81 (0.59, 1.10) | 0.80 (0.58, 1.11) |
| 9 months | 1.08 (0.84, 1.39) | 1.07 (0.83, 1.39) | 0.63 (0.44, 0.90) | 0.62 (0.43, 0.90) |
| 12 months | 0.80 (0.62, 1.04) | 0.79 (0.60, 1.03) | 0.74 (0.53, 1.03) | 0.72 (0.51, 1.02) |
RRR: Relative risk ratio.
CI: Confidence interval.
Multinomial logistic regression of non-hazardous and hazardous drinking compared to no current drinking in the year following HCT, among HIV infected baseline drinkers
| | ||||
|---|---|---|---|---|
| | | | | |
| Female | 1.00 | 1.00 | 1.00 | 1.00 |
| Male | 1.93 (1.32, 2.82) | 1.92 (1.31, 2.82) | 1.65 (0.96, 2.86) | 1.42 (0.78, 2.56) |
| | | | | |
| 18–25 | 1.00 | - | 1.00 | - |
| 26–35 | 1.00 (0.62, 1.59) | | 0.76 (0.38, 1.55) | |
| >35 | 1.21 (0.70, 2.08) | | 0.80 (0.35, 1.81) | |
| | | | | |
| Primary education or less | 1.00 | - | 1.00 | - |
| More than primary education | 1.17 (0.81, 1.71) | | 1.25 (0.72, 2.16) | |
| | | | | |
| Laborer | 1.00 | - | 1.00 | - |
| Business/sales/technical | 0.72 (0.47, 1.10) | | 0.96 (0.53, 1.74) | |
| Other | 0.86 (0.51, 1.46) | | 1.14 (0.55, 2.35) | |
| | | | | |
| Protestant | 1.00 | - | 1.00 | - |
| Catholic | 0.87 (0.58, 1.29) | | 0.83 (0.47, 1.45) | |
| Moslem | 0.66 (0.32, 1.34) | | 0.46 (0.15, 1.48) | |
| Saved/Pentecostal/Other | 0.49 (0.18, 1.37) | | 0.86 (0.24, 3.01) | |
| | | | | |
| Married | 1.00 | - | 1.00 | - |
| Previously married | 0.79 (0.53, 1.17) | | 0.92 (0.51, 1.64) | |
| Never married | 0.83 (0.46, 1.51) | | 1.51 (0.70, 3.24) | |
| | | | | |
| Low | 1.00 | - | 1.00 | - |
| Medium | 1.04 (0.69, 1.56) | | 1.20 (0.67, 2.15) | |
| High | 0.91 (0.50, 1.64) | | 1.60 (0.75, 3.43) | |
| | | | | |
| Sometimes/Often (>2 times/month) | 1.00 | - | 1.00 | - |
| Seldom (1–2 times/month) | 0.76 (0.39, 1.49) | | 1.00 (0.41, 2.46) | |
| Never | 0.81 (0.50, 1.32) | | 0.85 (0.43, 1.69) | |
| | | | | |
| Strong support | 1.00 | - | 1.00 | - |
| Moderate support | 0.59 (0.36, 0.96) | | 0.58 (0.28, 1.19) | |
| Poor support | 0.69 (0.38, 1.25) | | 0.90 (0.41, 1.99) | |
| | | | | |
| No | 1.00 | 1.00 | 1.00 | 1.00 |
| Yes | 1.49 (0.96, 2.31) | 1.42 (0.91, 2.23) | 3.21 (1.79, 5.75) | 3.15 (1.74, 5.70) |
| | | | | |
| None | 1.00 | - | 1.00 | - |
| Any | 1.04 (0.68, 1.59) | | 1.52 (0.85, 2.72) | |
| | | | | |
| Inpatient wards | 1.00 | 1.00 | 1.00 | 1.00 |
| Outpatient clinics | 1.04 (0.62, 1.75) | 1.09 (0.65, 1.83) | 0.70 (0.34, 1.42) | 0.65 (0.30, 1.41) |
| Emergency/casualty wards | 0.52 (0.27, 1.01) | 0.57 (0.29, 1.13) | 0.24 (0.08, 0.72) | 0.26 (0.08, 0.85) |
| | | | | |
| Just wanted to know/plan for future | 1.00 | - | 1.00 | - |
| AIDS symptoms/concern about current illness | 0.84 (0.57, 1.24) | | 1.40 (0.80, 2.46) | |
| Other | 1.50 (0.64, 3.49) | | 2.71 (0.93, 7.92) | |
| | | | | |
| Abbreviated HCT | 1.00 | - | 1.00 | - |
| Traditional HCT | 0.96 (0.66, 1.41) | | 1.01 (0.59, 1.72) | |
| | | | | |
| Enhanced linkage to care | 1.00 | - | 1.00 | - |
| Standard linkage to care | 0.97 (0.67, 1.42) | | 0.98 (0.57, 1.67) | |
| | | | | |
| 3 months | 1.00 | 1.00 | 1.00 | 1.00 |
| 6 months | 0.83 (0.56, 1.21) | 0.89 (0.60, 1.33) | 0.65 (0.40, 1.08) | 0.68 (0.40, 1.16) |
| 9 months | 1.27 (0.88, 1.84) | 1.48 (1.00, 2.22) | 0.75 (0.42, 1.36) | 0.84 (0.45, 1.57) |
| 12 months | 0.69 (0.47, 1.01) | 0.83 (0.54, 1.26) | 0.78 (0.48, 1.26) | 0.88 (0.52, 1.49) |
| | | | | |
| <200 | 1.00 | - | 1.00 | - |
| 200–349 | 1.59 (0.94, 2.68) | | 1.15 (0.53, 2.47) | |
| 350–499 | 1.81 (1.03, 3.18) | | 1.50 (0.68, 3.28) | |
| > = 500 | 1.60 (0.95, 2.71) | | 1.47 (0.68, 3.19) | |
| | | | | |
| No | 1.00 | 1.00 | 1.00 | 1.00 |
| Yes | 0.52 (0.36, 0.76) | 0.50 (0.33, 0.76) | 0.68 (0.38, 1.21) | 0.61 (0.33, 1.13) |
RRR: Relative risk ratio.
CI: Confidence interval.