Evaluating Thrombopoietin's Potential to Predict Adverse Cardiovascular Events in Patients With Peripheral Arterial Disease

Thrombopoietin (TPO) is a humoral growth factor that can induce megakaryocyte proliferation and differentiation. Elevated levels of TPO hve previously been posited as a marker of cardiovascular disease. In this investigation, we sought to evaluate the predictive potential of TPO of adverse cardiovascular events in patients with peripheral arterial disease (PAD). Patients presenting to ambulatory clinics at St Michael's Hospital were recruited for this study. Overall, 403 patients (n = 256 PAD and n = 147 non-PAD) participated in this study. Baseline levels of TPO were measured and quantified, and study participants were prospectively followed over a 2-year period. In this investigation, major adverse limb event (MALE; a composite of need for vascular intervention or major amputation) served as the primary outcome, whereas worsening PAD status (drop in ankle-brachial index ≥0.15) was the secondary outcome. Adjusted multivariable regression were performed to assess the prognostic value of TPO in predicting MALE and worsening PAD status. Plasma TPO levels (ng/mL) were significantly higher in patients with PAD (1.873 ± 0.746) than those without PAD (1.175 ± 0.631) (P-value = 26). The primary outcome of MALE outcomes occurred in 78 patients (19%). Individual components of MALE, namely need for arterial revascularization and need for major limb amputation, occurred in 72 patients (18%) and 15 patients (4%), respectively. The secondary outcome, decrease in ankle-brachial index (≥0.15), occurred in 36 patients (9%). With regard to predictive potential, TPO demonstrated adequate prognostic capabilities with a significant hazard ratio of 1.12 (95% confidence interval, 1.09-1.38; P-value = .003) for MALE, but not worsening PAD status (hazard ratio, 1.08; 95% confidence interval, 0.98-1.29; P-value = .27). Our analyses demonstrate the capabilities of TPO in predicting MALE, but not worsening PAD status.