Table 2.
Studies comparing self-report rates of ARV adherence with objectively measured rates
| Study (year), sample size | Self-report item and recall period | Response options | Self-reported adherence rates | Objective adherence measure and time period | Objectively measured adherence rates | Measure of association |
|---|---|---|---|---|---|---|
| Fletcher et al. [21] (2005), n = 266 | “How many pills did you skip taking yesterday?”, “…2 days ago?”, “…3 days ago?”, “…4 days ago?”; recall period: n/r* | Continuous numeric responses† | Mean (SD): 82 (32); median (IQR): 100 (75–100) | Continuous EDM rate; time period: 16 weeks | Mean (SD): 72 (29); median (IQR): 82 (50–98) | Pearson’s r = −0.24; Spearman’s rho = 0.20 |
| Halkitis et al. [22] (2005), n = 300 | “How many full doses have you missed taking?”; recall period: 2 weeks | Continuous numeric responses† | Mean (SD): 95 (9) | Continuous EDM rate; time period: 2 weeks | Mean (SD): 90 (18) | r = 0.32 |
| Holzemer et al. [24] (2006)‡, n = 240 | Morisky: 4 yes/no questions summed to obtain score ranging from 0–4§; recall period: n/a | Dichotomous score of 4 = adherent | 26% adherent | Dichotomous PC cutpoint 95%; time period: 1 month Dichotomous PR¶ < cutpoint 95%; time period: 6 months |
29% adherent‡ 40% adherent‡ |
Phi correlation = 0.24 Phi correlation = 0.16 |
| Kerr et al. [29] (2008), n = 88 | “How often did you take your medications as prescribed?”; recall period: 6 months | 5 levels from “always” to “never”; dichotomous “always” or “usually” = adherent | 92% adherent | Continuous PR rates; dichotomous cut point 75%; time period: 6 months | 48% adherent | Continuous: r = −0.06; dichotomous: odds ratio = 1.66 (95% CI = 0.35–7.90) |
| Liu et al. [26] (2006), n = 305 | “How many times did you miss a dose?”; recall period: combined 3 and 7 days | Dichotomous cutpoints 90% and 95% | Mean: 96 | Composite adherence score**; dichotomous cutpoints 90% and 95%; time period: 4 weeks | Mean: 81 | 90% cutpoint: sensitivity = 24%, specificity = 94%; 95% cutpoint: sensitivity = 31%, specificity = 93% |
| Lu et al. [4•] (2007), n = 156 | “How many pills did you skip taking yesterday?”, “…2 days ago?”, “…3 days ago?”; recall period: 3 days | Continuous numeric responses† | Mean (SD): 89.7 (25.3); median: 100 | Continuous EDM; time period: 3 days | 3-day EDM mean (SD): 72.4 (32.4); median: 83.3 | r = 0.50†† |
| “How many doses did you miss?”; recall period: 7 days | Continuous numeric responses | Mean (SD): 84.9 (26.4); median: 100 | Continuous EDM; time period: 7 days | 7-day EDM mean (SD): 70.6 (32.5); median: 85.7 | r = 0.49†† | |
| Frequency: “Did you take all your medications?”; recall period: 30 days | 6 levels: “none of the time” to “all of the time” | Mean (SD): 81.5 (24); median: 80 | Continuous EDM; time period: 30 days | Same as above | r = 0.51†† | |
| Percent: “What percent of the time were you able to take all your medications exactly as your doctor prescribed them?”; recall period: 30 days | 11 levels from 0%–100% | Mean (SD): 82.2 (21.5); median: 90 | Continuous EDM; time period: 30 days | 30-day EDM mean (SD): 69.8 (30.9); median: 83.3 | r = 0.45†† | |
| Rating: “Rate your ability to take all your medications as prescribed”; recall period: 30 days | 6 levels: “very poor” to “excellent” | Mean (SD): 72.7 (25.9); median: 80 | Continuous EDM; time period: 30 days | Same as above | r = 0.48‡‡ | |
| Average of frequency, percent, and rating items; recall period: 30 days | n/a | Mean (SD): 78.8 (21); median: 83.3 | Continuous EDM; time period: 30 days | Same as above | r = 0.55†† | |
| Munoz-Moreno et al. [25] (2007), n = 464 | “How many doses did you miss?”; recall period: 7 days and 1 month | Continuous numeric responses†; dichotomous cutpoint 95% | 7-days mean (SD): 98 (8); 1 month mean (SD): 9 (12) | Continuous EDM < 95% vs ≥ 95%; time period: 1 month | 7 days mean (SD): 89.7 (21.8); 1 month mean (SD): 91.8 (16.7) | 75% agreement by Bland and Altman method |
| Muyingo et al. [23] (2008), n = 2957 | “Did you miss any dose?”; recall period: 4 days | No = adherent No = adherent |
48% adherent 28% adherent |
PC < 100% vs 100%; time period: 1 month | n/r | kappa < 0.15 kappa = 0.44; sensitivity = 40%; specificity = 97% |
| Pearson et al. [27•] (2007)§§, n = 136 | “How many times did you take your medication yesterday?”, “…2 days ago?”, “…3 days ago?”; recall period: 3 days | Continuous numeric responses† | Mean (SD): 80 (34) | Continuous EDM; time period: 3 days | Mean (SD): 54 (40) | r = 0.41 |
| “How often did you miss a dose of your medication?”; recall period: 28 days | 6 levels from “every day” to “not once” (ordinal scale) | n/a | Continuous EDM; time period: 28 days | Mean (SD): 54 (40) | r = 0.30 | |
| Deschamps et al. [28] (2008), n = 133 | Overall doses taken; recall period: 1 month | 11 levels from 0%– 100%; dichotomous cutpoint 100% | 98 | EDM; time period: 50 days¶¶ | 91% adherent | Sensitivity = 57%; specificity = 66% |
| “How often did you miss a dose of your HIV medication?”; recall period: 1 month | 6 levels: “never” to “every day”; “never” = adherent | 79% adherent | EDM; time period: 50 days | Same as above | Sensitivity = 38%; specificity = 80% | |
| “During the past 30 days, how many times did you not take any of these pills?”; recall period: 1 month | Continuous numeric responses†; dichotomous cutpoint 100% | 99 | EDM; time period: 50 days | Same as above | Sensitivity = 33%; specificity = 92% |
*
2 or 4 days (personal communication with author).
†
Standard formula for converting numeric responses to adherence rate: [(number of pills prescribed − number of pills missed) / number of pills prescribed] × 100.
‡
Baseline values reported.
§
Morisky scale questions: 1) Do you ever forget to take your medications?; 2) Are you careless at times about taking your medications?; 3) When you feel better, do you sometimes stop taking your medicine?; 4) Sometimes, if you feel worse when you take your medicine, do you stop taking it?
¶
Prior to baseline.
**
Composite adherence score uses a hierarchic algorithm to combine adherence data from electronic drug monitoring and pill count.
††
Significantly greater than EDM rate.
‡‡
Not significantly different from EDM rate.
§§
Data from 3-month time point.
¶¶
EDM time period of 50 days is 3 months minus first 40 days of the monitoring period.
ARV—antiretroviral; EDM—electronic drug monitoring; IQR—interquartile range; n/a—not applicable; n/r—not reported; PC—pill count; PR—pharmacist refill; SD—standard deviation.