Bacterial infections risk scale for injection drug use: A brief screener to identify skin and soft tissue infection risk for people who inject drugs

Introduction

Skin and soft tissue infections (SSTI) and severe injection-related infections (SIRI) cause serious morbidity among people who inject drugs (PWID). Data suggest that specific injection practices associate with a higher risk of developing SSTI/SIRI, and that a brief screening tool may help identify at-risk individuals. This study examines injection drug use behaviors and SSTI/SIRI experiences among a sample of PWID in New York City (NYC). In particular, the analysis explores the potential utility of the bacterial infections risk scale for injection drug use (BIRSI) in identifying people at risk for developing SSTI/SIRI in a non-hospitalized population of PWID.

Methods

This study examines associations between sociodemographic factors, healthcare system usage, injection practices, and the seven-item BIRSI instrument in relation to reported past 90-day SSTI/SIRI among a subset of respondents who reported past 90-day injection drug use (146 total respondents). Each respondent received a composite score for the BIRSI instrument by adding a point for each reported behavior. Analyses examine the association between select factors and reporting ≥1 SSTI/SIRI in the past 90 days.

Results

Among participants, 55.5 % identified as Hispanic and 30.1 % as female. The mean age was 44.6 years and 32.2 % had stable housing. The prevalence of reported past 90-day SSTI/SIRI was 24.7 %. Unadjusted univariate models showed age (prevalence ratio, PR: 0.97, 95 % CI: 0.94, 0.99), receptive syringe sharing (RSS) (PR: 2.91, 95 % CI: 1.69, 4.88) or using other people's previously used (non-syringe) injection equipment (PR: 2.61, 95 % CI: 1.53, 4.45), and a higher BIRSI composite score (PR: 1.33, 95 % CI, 1.34, 1.56) to associate with reporting of past 90-day SSTI/SIRI. Further modeling showed that a higher BIRSI score, exclusive of other injection related behaviors, was associated with self-reported SSTI/SIRI (adjusted PR: 1.35, 95 % CI: 1.13, 1.62) when controlling for age, sex, race, and housing status.

Conclusion

Findings suggest the BIRSI instrument may be a useful, brief tool to identify individuals at higher risk of developing SSTI/SIRI among non-hospitalized PWID. Using the BIRSI instrument can help programs and staff serving PWID to implement strategies to reduce SSTI/SIRI risk among their participants, such as wound prevention and care interventions.