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

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. Eligible were primary studies reporting non-catheter-related or catheter-related thromboembolic (CRT) events in adults who received parenteral antibiotics in home or outpatient settings. In all, 43 studies involving 23,432 patient-episodes were reviewed. Four studies reported non-catheter related VTE while 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%), respectively. Heterogeneity was largely attributed to risk of bias by meta-regression (R2 = 21%). Excluding high-risk studies, CRT risk was 0.8% (95% CI, 0.5 - 1.2%; PI, 0.1 - 4.5%). From 25 studies, pooled CRT rate per 1,000 catheter-days was 0.37 (95% CI, 0.25 - 0.55; PI, 0.08 - 1.64). Our findings do not support universal thromboprophylaxis nor routine use of inpatient VTE risk assessment model in the OPAT setting. However, 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.