Incidence and risk factors for healthcare utilisation among patients discharged on outpatient parenteral antimicrobial therapy

Outpatient parenteral antimicrobial therapy (OPAT) programmes facilitate hospital discharge, but patients remain at risk of complications and consequent healthcare utilisation (HCU). Here we elucidated the incidence of and risk factors associated with HCU in OPAT patients. This was a retrospective, single-centre, case-control study of adult patients discharged on OPAT. Cases (n = 63) and controls (n = 126) were patients that did or did not utilise the healthcare system within 60 days. Characteristics associated with HCU in bivariate analysis (P ≤ 0.2) were included in a multivariable logistic regression model. Variables were retained in the final model if they were independently (P < 0.05) associated with 60-day HCU. Among all study patients, the mean age was 55 ± 16, 65% were men, and wound infection (22%) and cellulitis (14%) were common diagnoses. The cumulative incidence of 60-day unplanned HCU was 27% with a disproportionately higher incidence in the first 30 days (21%). A statin at discharge (adjusted odds ratios (aOR) 0.23, 95% confidence intervals (CIs) 0.09-0.57), number of prior admissions in past 12 months (aOR 1.48, 95% CIs 1.05-2.10), and a sepsis diagnosis (aOR 4.62, 95% CIs 1.23-17.3) were independently associated with HCU. HCU was most commonly due to non-infection related complications (44%) and worsening primary infection (31%). There are multiple risk factors for HCU in OPAT patients, and formal OPAT clinics may help to risk stratify and target the highest risk groups.