Fairly recent overview of predictors of HIV medication adherence:
Ammassari, A., Trotta, M. P., Murri, R., Castelli, F., Narciso, P., Noto, P., et al. (2002). Correlates and predictors of adherence to highly active antiretroviral therapy: Overview of published literature. JAIDS-Journal Of Acquired Immune Deficiency Syndromes 31(Suppl. 3), S123-S127.
Covers mostly demographic variables, but exhaustive.