Substance Abuse-Related Soft Tissue Infections: A Uniquely Complicated Subset of a Common Problem

We hypothesize that soft tissue infections (SSIs) related to intravenous drug usage (IVDU) are associated with a more complicated and costly course than those not associated with IVDU. For the period 2005-2018, ICD 9/ICD 10 billing codes were used to identify patients admitted with SSIs and their causes/complications and associated costs. IVDU-related infections were then compared with non-IVDU-related infections. t test was used to compare treatment costs and length of stay. Logistic regression analysis was used to assess the likelihood/risk of specific events in the IVDU versus non-IVDU populations. Of 47,281 patients admitted with SSIs, 1323 were associated with IVDU. IVDU-related patients tended to be younger (36.2 vs 49.3 years, P = 0.001). Both cost and length of stay were significantly greater in the IVDU group ($30,471 vs $16,020, P = 0.001; 5.7days vs 3.7days, P = 0.001). In addition, IVDU admissions were more likely to be associated with chronic blood-borne infections (hepatitis B/C, HIV, P = 0.001) and a significantly greater incidence of secondary infectious complications, including endocarditis (P = 0.001), bacteremia (P = 0.001), and osteomyelitis (P = 0.003). SSI admissions related to IVDU are a unique subgroup of patients. These patients not only have longer and more costly lengths of stay but are also at higher risk for secondary complications such as chronic blood-borne viral illness and secondary bacterial infectious complications, such as bacteremia, endocarditis, and osteomyelitis. Further prospective study of these findings is warranted as we continue to battle the growing problem of IVDU in the United States.