Venous Thromboembolism Risk Associated with MIDLINE Catheters and Peripherally Inserted Central Catheters, a Systematic Review and Meta-Analysis

Background Peripherally inserted central catheters (PICCs) and midline catheters (MCs) are widely used for medium- to long-term vascular access in hospitalized adults. While PICCs are associated with a known risk of venous thromboembolism (VTE), the thrombotic safety profile of MCs remains uncertain, with conflicting evidence and inconsistent definitions complicating risk assessments. Objective To compare the incidence of VTE, including deep vein thrombosis (DVT), superficial venous thrombosis (SVT), and pulmonary embolism (PE), between PICCs and MCs through a systematic review and meta-analysis of observational and randomized studies. Methods A systematic literature search across five databases. Data extraction and bias assessment were performed independently by two reviewers. The primary outcome was the incidence of VTE, defined in studies by DVT, SVT, PE, and catheter-related thrombosis (CRT) by catheter type. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using random- and common-effects models. Subgroup and sensitivity analyses explored heterogeneity by catheter type, insertion technique, placement setting, and publication period. Results A total of 29,680 catheters were included across 19 studies, comprising 14,200 MCs and 15,480 PICCs. The pooled analysis showed no statistically significant difference in overall VTE rates between MCs (3.5%) and PICCs (3.8%), with a pooled OR of 0.92 (95% CI: 0.70-1.22). Similarly, CRT rates did not differ significantly between the two device types (OR = 1.14, 95% CI: 0.74-1.76). In the subgroup of studies enrolling ≥ 25% of patients from intensive care units (ICUs), no significant difference in thrombotic risk was observed between MCs and PICCs (OR = 0.88, 95% CI: 0.72-1.07). No significant differences in VTE risk were observed when stratified by placement technique, clinical setting, or publication period. Across studies, reporting of critical patient-level risk factors and catheter characteristics was frequently incomplete or inconsistent. Conclusion Our analysis suggests MCs have no significant differences in the thrombotic profile compared to PICCs. Therefore, VTE risk alone should not determine catheter choice. Future prospective studies with standardized definitions and improved reporting are essential to guide optimal vascular access decisions in high-risk populations.