Measuring medication adherence: are missed doses reported more accurately then perfect adherence?

Self-reports overestimate adherence compared to more objective measures suc h as electronic monitoring. However, self-report is the most feasible metho d for clinical settings; therefore, it is important to identify the context in which this method can provide an accurate assessment. To address whethe r self-reports are more accurate when missed doses are reported, we conduct ed a secondary analysis of data fi om a methodological study comparing mult iple measures of adherence (including self-report and electronic monitoring ) to a two-week placebo regimen mimicking HAART among 30 HIV-positive patie nts not on HAART. Results indicated a mean adherence of 85% and 62%, as mea sured by self-report and electronic monitoring, respectively. Self-report a nd electronic monitoring were not significantly correlated in the measureme nt of proportion of prescribed doses taken among the sub-group of 17 patien ts who reported missed doses (r = 0.22), nor among those who reported no mi ssed doses, or the group as a whole. Using electronic monitoring as the val idity criterion, these findings indicate that self-reports overestimate adh erence even among patients who report missed doses.