Determinants of hospitalizations for pneumonia among Finnish drug users

OBJECTIVE: The study examined the determinants of being hospitalized for pneumonia in a large cohort of drug users. METHODS: Information of 4817 clients seeking treatment for illicit drug use was linked with the Finnish hospital discharge register to identify those who were hospitalized with main/primary diagnoses of pneumonia during 1997-2013. Cox regression models were used to examine the association between age, gender, homelessness, and route of drug administration of the primary drug at initial clinical consultation and pneumonia hospitalization. Findings were presented as adjusted hazard ratios and 95% confidence intervals. RESULTS: There were 354 persons diagnosed with pneumonia, with a total of 522 hospitalizations at the end of 2013. The univariate Cox models revealed that being over 44 years of age, male gender, homelessness, and intravenous drug use at initial clinical consultation increased the risk of being hospitalized for pneumonia. In the fully adjusted multivariate model, being over 44 years was the strongest factor independently associated with pneumonia hospitalization (adjusted hazard ratio: 2.67, 95% confidence interval: 1.56-4.57, p < 0.001), followed by homelessness (adjusted hazard ratio: 1.75, 95% confidence interval: 1.38-2.22, p < 0.001) and intravenous drug use (adjusted hazard ratio: 1.27, 95% confidence interval: 1.01-1.59, p = 0.041). Of the 354 clients hospitalized for pneumonia, 31.9% (n = 113) were rehospitalized within 30 days of being discharged. One-third of the reasons for the 30-day rehospitalization were pneumonia-related. CONCLUSION: Vaccination, measures addressing housing instability, safe injecting and good hygienic practices, and treating underlying drug use problems could help to reduce morbidity for pneumonia in this cohort.