Adherence to antiretroviral therapy assessed by unannounced pill counts conducted by telephone

Background: Unannounced pill counts conducted in patients' homes is a valid objective method for monitoring medication adherence that is unfortunately costly and often impractical. Conducting unannounced pill counts by telephone may be a viable alternative for objectively assessing medication adherence. Purpose: To test an unannounced pill count assessment of adherence conducted by telephone. Methods: HIV-positive men and women (N = 77) in Atlanta GA completed an unannounced telephone-based pill count immediately followed by a pill count conducted in an unannounced home visit. Results: A high degree of concordance was observed between phone and home-based number of pills counted (Intraclass correlation, ICC = .997, 95% CI .995-.998, P < .001) and percent of pills taken (ICC = .990, 95% CI .986-.992, P < .001). Concordance between adherence above/below 90% and phone/home counts was 95%, Kappa coefficient = .995. Concordance between pill counts was not influenced by participant education or health literacy and was maintained when the data were censored to remove higher levels of adherence. Analyses of discordant pill counts found the most common source of error resulted from overcounted doses in pillboxes on the telephone. Conclusions: Unannounced phone-based pill counts offer an economically and logistically feasible objective method for monitoring medication adherence.