How late is too late? Timeliness to scheduled visits as an antiretroviral therapy adherence measure in Nairobi, Kenya and Lusaka, Zambia

Abstract

Collecting self-reported data on adherence to highly active antiretroviral therapy (HAART) can be complicated by patients’ reluctance to report poor adherence. The timeliness with which patients attend visits might be a useful alternative to estimate medication adherence. Among Kenyan and Zambian women receiving twice daily HAART, we examined the relationship between self-reported pill taking and timeliness attending scheduled visits.

We analyzed data from 566 Kenyan and Zambian women enrolled in a prospective 48-week HAART-response study. At each scheduled clinic visit, women reported doses missed over the preceding week. Self-reported adherence was calculated by summing the total number of doses reported taken and dividing by the total number of doses asked about at the visit attended. A participant's adherence to scheduled study visits was defined as “on time” if she arrived early or within three days, “moderately late” if she was four–seven days late, and “extremely late/missed” if she was more than eight days late or missed the visit altogether.

Self-reported adherence was <95% for 29 (10%) of 288 women who were late for at least one study visit vs. 3 (1%) of 278 who were never late for a study visit (odds ratios [OR] 10.3; 95% confidence intervals [95% CI] 2.9, 42.8). Fifty-one (18%) of 285 women who were ever late for a study visit experienced virologic failure vs. 32 (12%) of 278 women who were never late for a study visit (OR 1.7; 95% CI 1.01, 2.8). A multivariate logistic regression model controlling for self-reported adherence found that being extremely late for a visit was associated with virologic failure (OR 2.0; 95% CI 1.2, 3.4).

Timeliness to scheduled visits was associated with self-reported adherence to HAART and with risk for virologic failure. Timeliness to scheduled clinic visits can be used as an objective proxy for self-reported adherence and ultimately for risk of virologic failure.

Keywords:

• adherence
• self-reported adherence
• timeliness to visit
• virologic failure
• antiretroviral
• human immunodeficiency virus (HIV)
• Africa

Acknowledgements

Funding was provided by the US Centers for Disease Control and Prevention (CDC) through The US President's Emergency Plan for AIDS Relief. CDC staff participated in the design, data collection, analysis, and interpretation of the data; writing the report; and decision to submit the paper for publication. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.

Notes

1. Preliminary data from this paper were presented at the 17th International AIDS Society Conference, Mexico City, Mexico, August 2008.