Application of syndemic theory to heroin dependence among a sample of drug users

Syndemic theory, first proposed by Merrill Singer, posits that some populations experience multiple epidemics and endemics that interact synergistically to decrease the health of individuals and populations. Few studies have applied syndemic theory to drug users. We examined the relationship between syndemic burden and heroin dependence among injection (n=330) and non-injection drug users (n=519) recruited in NYC between 2005 and 2009. Using an additive syndemic model, a current total syndemic burden score was created by summing seven binary variables including: recent (1) reduced material resources, (2) homelessness, (3) PTSD, (4) depression, (5) physical intimate partner violence, (6) sexual intimate partner violence, and lifetime (7) history of incarceration. The mean syndemic burden was 2.9 (SD=1.5, range:0-7). Past year heroin dependence was measured using an 11-item scale based on DSM-IV criteria; 45.1% were heroin dependent. Heroin dependent individuals had a significantly higher mean syndemic burden score as compared to those who were not dependent (2.7 vs. 3.2, p<0.001). In a multivariate logistic regression model, the syndemic score was significantly associated with heroin dependence (OR=1.19, 95% CI=1.05, 1.35) after controlling for gender, sexual identity, race, age, education, marital status, cocaine and crack dependence, and alcohol, marijuana, PCP, LSD and injection drug use. Syndemic theory is salient to the experiences of illicit drug users. Drug users in this sample experienced multiple syndemic burdens, which were significantly associated with drug use severity. These data suggest that drug users would benefit from integrated service and treatment programs that simultaneously address their multiple needs.