Can the Caprini score predict thromboembolism and guide pharmacologic prophylaxis after primary joint arthroplasty?

Venous thromboembolism (VTE) has a 30-day mortality rate of between 10 and 30%. The Caprini score is a VTE risk assessment model, which assigns points to 20 past medical history and current health factors. We hypothesized that the Caprini score could predict VTE incidence and recommend prophylaxis following total joint arthroplasty.

We performed a retrospective review of prospectively collected institutional data identifying Caprini scores on 2155 primary hip (n = 840) and knee (n = 1315) arthroplasties. Surgeons were blinded to Caprini scores when prescribing VTE prophylaxis. Patients were separated into prophylaxis groups receiving Aspirin (81 mg BID or 325 mg BID) or other (Rivaroxaban, Warfarin, Enoxaparin, Apixaban, Dabigatran, Heparin). Univariate, multivariate, and Cohen's effect size analyses assessed the predictive power of the Caprini score on VTE incidence.

The mean Caprini score was 9.49 (5-25). A majority, 83% (1792) of patients were in the Aspirin group, and 17% (363) in the other group. Other prophylaxis patients had statistically significantly higher Caprini scores (10 vs. 9, p < 0.0001). Twenty-five (1.2%) patients developed VTE. Controlling for prophylaxis, higher Caprini scores increased VTE risk, but this wasn't statistically significant (p = 0.16). Multivariate analysis showed a non-significant effect for patients with BMIs >40 or Caprini scores ≥11 to predict VTE incidence in the Aspirin or other prophylaxis groups (p = 0.52 and p = 0.15 respectively). Cohen's effect size was small, comparing Caprini scores in patients who had and had not had a VTE in both Aspirin and other prophylaxis groups (Cohen's d = 0.25 and d = 0.16 respectively).

Surgeons rely on stronger pharmacologic prophylaxis for a select high risk group of their primary lower extremity total joint arthroplasty patients. When controlling for prophylaxis, the Caprini score had a small effect size and did not have the predictive power necessary to guide treatment.