Prevalence and correlates of obstructive lung disease among people who inject drugs, San Diego, California.

Background: Pulmonary tissue damage leading to obstructive lung disease (OLD) could result from intravenous administration of insoluble particles found in illicit drugs. This study described the prevalence and identified correlates of OLD among people who inject drugs (PWID).

Methods: In 2012-2016, a community-based cohort of PWID who had injected within the past month were enrolled in a study to assess HIV, hepatitis C virus (HCV) andMycobacterium tuberculosis (Mtb) infections and their related risk factors. Data were obtained through face-to-face interviews, serological testing and spirometry. Baseline data were used for a cross-sectional analysis of the prevalence and correlates of OLD, defined as FEV1/FVC < 0.7. Univariate and multivariable logistic regression were used to identify factors associated with OLD.

Results: Among 516 participants who had complete spirometry and interview results, the mean age was 43.3 years, 73.6 % were male, 9.5 % were Black, 91.1 % smoked cigarettes and 18.2 % had OLD. Few (9.6 %) PWID with OLD reported a previous diagnosis of COPD although many (44.7 %) reported related symptoms. Black race (AOR = 2.66, 95 %CI: 1.37, 5.17), pack-years smoked (AOR = 1.06/5 years, 95 %CI: 1.01, 1.12), and duration of injection drug use (AOR = 1.13, 95 %CI: 1.01, 1.27) were independently associated with OLD after controlling for age.

Conclusions: The prevalence of OLD was high in this cohort and associated with Black race and cigarette smoking-known risk factors. In addition, OLD prevalence increased with greater duration of injection drug use, suggesting a link between cumulative exposure to injected insoluble particles and OLD. Further examination of these adulterants and lung pathology are needed.