Outpatient parenteral antimicrobial therapy (OPAT) in a teaching hospital-based practice: a retrospective cohort study describing experience and evolution over 10 years.

Use of outpatient parenteral antimicrobial therapy (OPAT) is increasing in settings with advanced healthcare systems internationally. This study describes a large OPAT service cohort developed in the west of Scotland and includes trends over a 10-year period of this service. Data were retrieved from a prospectively maintained electronic case database. Patient and logistic variables were collated for all OPAT episodes (n=2638, resulting in 39035 days of patient care over 10 years). Skin and soft-tissue infections and bone and joint infections accounted for 77% of OPAT cases, but a wide range of other conditions have been treated in this cohort. Outcome variables were evaluated for all first OPAT attendances (n=2233), amongst which a successful outcome (cure or improvement) was found for 2063 (92.4%). Unplanned admission was observed in 9.1% of patients (6.3 events per 1000 OPAT patient days). Healthcare-associated infection rates were low: amongst first OPAT attendances, 14 intravenous line infections were observed (0.4 per 1000 OPAT patient days). Statistically significant trends over time included: a decrease in OPAT treatment time; increased referrals from non-local and secondary care sources; increased rate of co-morbidity of OPAT referrals; and increased self/carer administration of antimicrobials. Outcome proportions (success and adverse events) did not vary over time. This cohort study adds to the increasing observational data suggesting that OPAT is safe, effective and acceptable for treating a wide variety of infections. Observed trends over a 10-year period suggest that this model of infection management is adaptable and sustainable.