Prevalence of adverse events associated with potent antiretroviral treatment: Swiss HIV cohort study

In view of the adverse affects that accompany antiretroviral therapy, precise data on effects have long been indicated.

Background data on adverse events to antiretroviral treatment have been recorded in clinical trials, post-marketing analyses, and in anecdotal reports. But no systematic study has been done to assess adverse events. Using a standard clinical and laboratory method, the investigators evaluated the prevalence of adverse events in 1,160 patients who were receiving antiretroviral treatment. They measured the toxic effects associated with various regimens: protease inhibitor (PI), non-nucleoside and nucleoside analogue reverse transcriptase inhibitor and specific compounds.

Data were obtained from outpatients in the Swiss HIV Cohort Study using a structured interview and laboratory analyses to identify and describe all potential adverse events attributed to treatment according to standard definitions. Identification of independent associations using logistic regression analysis was also utilized. The Swiss HIV Cohort Study is a prospective cohort study of individuals with HIV-1 who were followed up in one of seven Swiss clinics. Patients were identified by the type of antiretroviral regimen they were on. Patients who had changed their regimen in the last 30 days were excluded from the study. During the visit, physicians completed a questionnaire based on classification used by the AIDS Clinical Trials group on adverse events.

According to the authors, “Physicians explicitly asked patients if symptoms listed in the questionnaire had arisen within the 30 days preceding the visit. Lipodystrophy was described according to Carr and colleagues. Potential adverse events were scored according to severity (1=mild, 2=moderate, 3=severe, 4=serious) and the likelihood of resulting from antiretroviral treatment (unlikely, possible, probable, and certain), after the definition of the World Health Organization.” Standard comprehensive laboratory assays were done on each patient on or immediately before (<10) their clinic visit.

The results of the study indicated that 47 percent of patients had clinical adverse affects from antiretroviral combination therapy. Nine percent of effects were graded as serious or severe. Twenty-seven percent of laboratory results showed adverse effects, and 16 percent of these were rated serious or severe. The more drugs taken in combination, the lower the HIV levels but the higher the likelihood of side effects.

According to the investigators, “It should be underscored that more than two-thirds of patients might have complaints if precisely questioned and that adverse events have an effect on adherence and on development of viral resistance, which might lead to treatment discontinuation or failure. Yearly surveys using the proposed cross-sectional analysis could help to assess changes in prevalence of specific toxic effects and in overall well-being of patients receiving antiretroviral treatment.” The authors, in addition, recommended that post-marketing surveillance of toxic effects be conducted by pharmaceutical companies.

Fellay J et al. Prevalence of adverse events associated with potent antiretroviral treatment: Swiss HIV Cohort Study. Lancet 2001 Oct 20;358(9290):1322-7.