A cohort study of drug users' compliance with zidovudine treatment

Objectives: Determine whether patients who have acquired the human immunodeficiency virus through injecting drug use receive less antiviral medication (zidovudine) than comparable patients of other risk groups considering access to, acceptance of, and compliance with treatment. Design: Historical cohort study. Setting: Human immunodeficiency virus outpatient clinic. Patients: Human immunodeficiency virus—infected subjects eligible for zidovudine treatment between January 1, 1989, and January 1, 1992, comparing injecting drug users (IDUs) with non-IDUs ("others"). Main Outcome Measures: Proposal, acceptance, start of, and compliance with zidovudine treatment. Results: One hundred fifty-one IDUs and 162 other human immunodeficiency virus—positive subjects became eligible for zidovudine treatment between January 1, 1989, and January 1, 1992. Both groups were proposed zidovudine as often, but zidovudine treatment was refused by 14.9% of IDUs compared with 7.1% of others (P=.029). The IDUs needed considerably more time than other subjects to accept zidovudine therapy (median delay between indication and start of zidovudine treatment, 61 days vs 30 days,P=.0001). After accepting, IDUs were as compliant with treatment as others: 81.3% vs 83.2% were good compliers, and rises of mean corpuscular volume of erythrocytes after 3 and 6 months of treatment were similar in both groups. Former drug users and IDUs receiving methadone were started on zidovudine treatment more often and complied better with treatment than active drug users. Absence of housing and presence of psychiatric diagnosis (both more prevalent in IDUs) were associated with less zidovudine treatment and worse compliance. Conclusion: Injecting drug users tend to delay the start of zidovudine treatment. However, once they have started, their compliance is no worse than the compliance of patients from other risk groups. These results have important implications for clinical trials, medical care, and public health. (Arch Intern Med. 1994;154:1121-1127)