Clinical pre-test probability adjusted versus age-adjusted D-dimer interpretation strategy for DVT diagnosis: A diagnostic individual patient data meta-analysis

Background: To increase the clinical usefulness of the D-dimer test in diagnosis of deep vein thrombosis (DVT), two strategies have been proposed: the age-adjusted, and the clinical pre-test probability (CPTP) adjusted interpretation. However, it is not known which of these strategies is superior. Objective: To conduct an individual patient data (IPD) meta-analysis that compares the sensitivity, specificity, negative predictive value (NPV), and utility (the proportion of all patients who have a negative D-dimer test) when the two strategies are used to interpret D-dimer results. Methods: Using an established IPD database, we conducted a meta-analysis to compare the two strategies. A bivariate random effects regression model was used to estimate and compare the pooled sensitivity and specificity simultaneously. The pooled NPV and utility of the two strategies was compared using a univariate random effects model. Results: Four studies were eligible for this analysis, with a total of 2554 patients. Overall prevalence of DVT was 12% with substantial heterogeneity between studies (P value <.001). Both strategies have high pooled NPVs (99.8%) with a difference of 0% (95% confidence interval [CI]: −0.1, 0.1). The difference between the pooled specificity of the CPTP-adjusted strategy (57.3%) and the age-adjusted strategy (54.7%) was 2.6% (95% CI: −7.7, 12.8). The CPTP-adjusted strategy (49.4%) has a marginally greater pooled utility compared with the age-adjusted approach (47.4%), with a pooled difference of 1.9% (95% CI: −0.1, 3.9). Conclusions: Both D-dimer interpretation strategies were associated with a high and similar NPV, and similar utility.