Objectives: To assess the relationship between various injecting drug use patterns and the rate of CD4+ lymphocyte decline in HIV-1-infected injecting drug users in Baltimore, Maryland, USA.
Methods: A cohort of 605 HIV-1-infected injecting drug users was recruited between 1988 and early 1989 in East Baltimore using extensive community outreach techniques. The participants were interviewed semi-annually to collect information on drug use practices. The outcome measure of interest was the rate of CD4+ lymphocyte decline between pairs of CD4+ lymphocyte counts. A mixed model was used to evaluate the relationship between the change in CD4+ lymphocyte count per month and previous CD4+ lymphocyte count and various drug use variables.
Results: The 605 HIV-infected injecting drug users had a median initial CD4+ lymphocyte count of 513 cells x 10(6)/l. Using 3209 paired observations, the mean change in CD4+ lymphocyte count was -3.2 cells x 10(6)/l per month. The rate of decline was higher in those with a higher level of CD4+ lymphocytes (P < 0.01) and length of drug use (P < 0.01), but did not vary by injection frequency or injection intensity of specific drug types. Although animal studies have suggested that the pattern of drug administration (continuous versus intermittent) and episodes of withdrawal or overdose might impact the rate of CD4+ lymphocyte decline, this was not observed in the present study.
Conclusion: Patterns of injecting drug use, based on self-report, were not associated with the rate of decline in CD4+ lymphocytes.