December 14, 2011
ALIVE (AIDS Linked to the Intravenous Experience) is a prospective cohort with semi-annual follow-up since 1988. The current study, set in Baltimore, was designed to determine the incidence of long-term injection cessation and its association with residential relocation and neighborhood deprivation. Its subjects were 1,697 active injectors from ALIVE with at least eight semi-annual study visits.
Multi-level discrete time-to-event models were constructed to investigate individual and neighborhood-level predictors of long-term injection cessation, which was defined as three consecutive years without self-reported injection drug use.
Forty-two percent of injectors (n=706) achieved long-term cessation (incidence=7.6 per 100 person-years). After adjusting for individual-level factors, the researchers found that long-term cessation was 29 percent less likely in neighborhoods in the third quartile of deprivation (hazard ratio=0.71, 95 percent confidence interval: 0.53, 0.95) and 43 percent less likely in the highest quartile of deprivation (HR=0.57, 95 percent CI: 0.43, 0.76) compared with the first quartile.
Residential relocation was found to be associated with an increased likelihood of long-term injection cessation (HR=1.55, 95 percent CI: 1.31, 1.82), although the authors noted that "the impact of relocation varied depending on the deprivation in the destination neighborhood." Compared to subjects who stayed in less deprived neighborhoods, the strongest positive impact on long-term cessation was noted among those who relocated from highly deprived to less deprived neighborhoods (HR=1.96, 95 percent CI: 1.50, 2.57). Staying in the most deprived neighborhoods was detrimental (HR=0.76, 95 percent CI: 0.63, 0.93) "Long-term cessation of injection of opiates and cocaine occurred frequently following a median of nine years of injection, and contextual factors appear to be important," the authors concluded. "Our findings suggest that improvements in the socio-economic environment may improve the effectiveness of cessation programs."