The relationship between injection and noninjection drug use and HIV disease progression

Background: Injection drug use is associated with poor HIV outcomes even among persons receiving highly active antiretroviral therapy (HAART), but there are limited data on the relationship between noninjection drug use and HIV disease progression.

Methods: We conducted an observational study of HIV-infected persons entering care between January 1, 1999, and December 31, 2004, with follow-up through December 31, 2005.

Results: There were 1,712 persons in the study cohort: 262 with a history of injection drug use, 785 with a history of noninjection drug use, and 665 with no history of drug use; 56% were White, and 24% were females. Median follow-up was 2.1 years, 33% had HAART prior to first visit, 40% initiated first HAART during the study period, and 306 (17.9%) had an AIDS-defining event or died. Adjusting for gender, age, race, prior antiretroviral use, CD4 cell count, and HIV-1 RNA, patients with a history of injection drug use were more likely to advance to AIDS or death than nonusers (adjusted hazard ratio [HR] = 1.97, 95% confidence interval [CI] = 1.43-2.70, p < .01). There was no statistically significant difference of disease progression between noninjection drug users and nonusers (HR = 1.19, 95% CI = 0.92-1.56, p = .19). An analysis among the subgroup who initiated their first HAART during the study period (n = 687) showed a similar pattern (injection drug users: HR = 1.83, 95% CI = 1.09-3.06, p = .02; noninjection drug users: HR = 1.21, 95% CI = 0.81-1.80, p = .35). Seventy-four patients had active injection drug use during the study period, 768 active noninjection drug use, and 870 no substance use. Analyses based on active drug use during the study period did not substantially differ from those based on history of drug use.

Conclusions: This study shows no relationship between noninjection drug use and HIV disease progression. This study is limited by using history of drug use and combining different types of drugs. Further studies ascertaining specific type and extent of noninjection drug use prospectively, and with longer follow-up, are needed.