Risk of venous thromboembolism in outpatient parenteral antimicrobial therapy (OPAT): A systematic review and meta-analysis

•Systematic review of venous thromboembolism (VTE) incidence in outpatient parenteral antimicrobial therapy (OPAT) settings.•Low incidence of catheter-related and non-catheter-related VTE in OPAT patients.•Findings do not support universal thromboprophylaxis or routine use of inpatient VTE risk assessment model in OPAT setting.•High index of suspicion should be maintained, especially for patients with known risk factors for VTE.•This study adds to the growing evidence that OPAT is a safe alternative to inpatient care. The risk of venous thromboembolism (VTE) in outpatient parenteral antimicrobial therapy (OPAT) is not fully understood and the optimal strategy for thromboprophylaxis remains unclear. This systematic review investigated the incidence of VTE in OPAT settings (PROSPERO CRD42022381523). MEDLINE, CINAHL, Emcare, Embase, Cochrane Library and grey literature were searched from earliest records to 18 January 2023. Primary studies reporting non-catheter-related VTE or catheter-related thromboembolism (CRT) events in adults who received parenteral antibiotics in home or outpatient settings were eligible. In total, 43 studies involving 23 432 patient episodes were reviewed, of which 4 studies reported non-catheter-related VTE and 39 included CRT. Based on generalised linear mixed-effects models, pooled risk estimates of non-catheter-related VTE and CRT were 0.2% [95% confidence interval (CI) 0.0–0.7%] and 1.1% [95% CI 0.8–1.5%; prediction interval (PI) 0.2–5.4%]. Heterogeneity was largely attributed to risk of bias by meta-regression (R2 = 21%). Excluding high-risk-of-bias studies, CRT risk was 0.8% (95% CI 0.5–1.2%; PI 0.1–4.5%). From 25 studies, the pooled CRT rate per 1000 catheter-days was 0.37 (95% CI 0.25–0.55; PI 0.08–1.64). These findings do not support universal thromboprophylaxis or routine use of an inpatient VTE risk assessment model in the OPAT setting. However, a high index of suspicion should be maintained, especially for patients with known risk factors for VTE. An optimised protocol of OPAT-specific VTE risk assessment should be sought.