Community-acquired Staphylococcus aureus bacteremia among people who inject drugs: a national cohort study in England, 2017-2020

Background:
People who inject drugs (PWID) are at increased risk of community-acquired Staphylococcus aureus bacteraemia (CA-SAB), but little is known about clinical outcomes of CA-SAB in PWID compared with the wider population of patients with CA-SAB.

Methods:
Three national datasets were linked to provide clinical and mortality data on patients hospitalised with CA-SAB in England between 1 January 2017 and 31 December 2020. PWID were identified using the ICD-10 code for "mental health and behavioural disorder due to opioid use" (F11). Multivariable logistic regression was used to estimate adjusted odds ratios (aORs) for associations of PWID with 30-day all-cause mortality and 90-day hospital readmission.

Results:
In 10,045 cases of CA-SAB, 1,612 (16.0%) were PWID. Overall, 796 (7.9%) patients died within 30 days of CA-SAB admission and 1,189 (11.8%) patients were readmitted to hospital within 90 days of CA-SAB. In those without infective endocarditis there was strong evidence of lower odds of mortality among PWID compared with non-PWID (aOR: 0.47, 95% confidence interval, CI: 0.33-0.68, p < 0.001) whereas there was no association in CA-SAB case fatality with endocarditis (aOR 1.40, CI 0.87-2.25, p = 0.163). PWID were less likely to be re-admitted within 90 days of CA-SAB (aOR 0.79, CI 0.65-0.95, p = 0.011).

Conclusions:
In this large cohort study of patients with CA-SAB in England, PWID had lower odds of death in the absence of endocarditis and lower odds of re-admission within 90 days compared to non-PWID patients. This study highlights the over-representation of PWID among patients with CA-SAB nationally.