Validation of Michigan risk score and D-dimer to predict peripherally inserted central catheter-related thrombosis: A study of 206,132 catheter days.

BACKGROUND: The Michigan Risk Score (MRS) was the only predicted score for peripherally inserted central venous catheters (PICC) associated upper extremity venous thrombosis (UEVT). Age-adjusted D-dimer increased the efficiency for UEVT. There were no external validations in an independent cohort.

METHOD: A retrospective study of adult patients with PICC insertion was performed. The primary objective was to evaluate the performance of the MRS and age-adjusted D-dimer in estimating risk of PICC-related symptomatic UEVT. The sensitivity, specificity and areas under the receiver operating characteristics (ROC) of MRS and age-adjusted D-dimer were calculated.

RESULTS: Two thousand one hundred sixty-three patients were included for a total of 206,132 catheter days. Fifty-six (2.6%) developed PICC-UEVT. The incidences of PICC-UEVT were 4.9% for class I, 7.5% for class II, 2.2% for class III, 0% for class IV of MRS ( p  = 0.011). The incidences of PICC-UEVT were 4.5% for D-dimer above the age-adjusted threshold and 1.5% for below the threshold ( p  = 0.001). The areas under ROC of MRS and age-adjusted D-dimer were 0.405 (95% confidence interval (CI) 0.303-0.508) and 0.639 (95% CI 0.547-0.731). The sensitivity and specificity of MRS were 0.82 (95% CI, 0.69-0.91), 0.09 (95% CI, 0.08-0.11), respectively. The sensitivity and specificity of age-adjusted D-dimer were 0.64 (95% CI, 0.46-0.79) and 0.64 (95% CI, 0.61-0.66), respectively.

CONCLUSIONS: MRS and age-adjusted D-dimer have low accuracy to predict PICC-UEVT. Further studies are needed.