Aims: Skin perfusion pressure (SPP) and ankle-brachial index (ABI) are useful in screening for peripheral arterial disease in patients undergoing hemodialysis (HD). We compared the prognostic abilities of the SPP and ABI in predicting the composite outcomes of mortality and atherosclerotic vascular events.
Methods: This single-center prospective cohort study enrolled 258 patients undergoing HD. The patients with SPP and ABI measurements were divided into tertiles. Log-rank tests, Cox regression analyses, and discrimination parameters were used for comparisons.
Results: Over a median follow-up period of 3.7 (1.4-5.0) years, 119 composite events were recorded. The incidence rates of composite events were 27.5, 13.3, and 9.1 per 100 person years, respectively, across the SPP tertiles (log-rank: p＜0.001), and 23.2, 13.2, and 11.6 per 100 person years across the ABI tertiles (p=0.003). With the 3rd tertiles as references, the 1st tertiles of the SPP and ABI were significantly associated with the composite outcome (adjusted hazard ratio [aHR]: 2.58, 95% confidence interval [CI]: 1.57-4.23 and aHR: 1.70, 95% CI: 1.06-2.73, respectively). Adding the tertiles of the SPP to a predictive model with established risk factors significantly improved the model performance. This improvement was larger than that of the ABI in terms of net reclassification (0.330 vs. 0.275) and integrated discrimination (0.045 vs. 0.012). Furthermore, in patients with a normal ABI, the 1st SPP tertile (＜71 mmHg) was significantly associated with the outcome (aHR, 1.97; 95% CI, 1.13-3.41) when compared to the 3rd tertile.
Conclusions: Even patients with a normal ABI have a poor prognosis if their SPP levels are low. SPP outperformed ABI in predicting mortality and cardiovascular outcomes in HD patients.
Keywords: Ankle-brachial index; Cardiovascular event; Hemodialysis; Mortality; Skin perfusion pressure.