Skin Perfusion Pressure Outperforms Ankle-Brachial Index in Predicting Mortality and Cardiovascular Outcomes in Hemodialysis Patients

Figures

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  Supplemental Fig.1. Correlation between SPP and ABI values. The scatterplot shows the relationship between SPP and ABI values. Pearson's correlation coefficient was calculated to be 0.56 (p＜0.001). Blue circles represent patients who did not experience any composite event of death and AVE, whereas red triangles represent those who did. We found that the blue circles were concentrated where both SPP and ABI were high. SPP, skin perfusion pressure; ABI, ankle-brachial index; AVE, atherosclerotic vascular event.

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  Fig.1. Cumulative incidence of outcomes stratified by SPP and ABI tertiles in all patients. Kaplan–Meier failure curves show the cumulative incidence of outcomes. In terms of the composite event at the 5-year time point, the tertiles were 0.74, 0.48, and 0.38 for SPP T1, T2, and T3, respectively (p＜0.001) (A), and 0.70, 0.48, and 0.44 for ABI T1, T2, and T3 (p=0.003) (D). For all-cause death, the tertiles were 0.52, 0.34, and 0.23, respectively for SPP (p=0.003) (B), and 0.47, 0.28, and 0.36 for ABI (p=0.069) (E). For AVEs, the tertiles were 0.60, 0.35, and 0.27, respectively, for SPP (p＜0.001) (C) and 0.56, 0.37, and 0.26 for ABI (p=0.005) (F). SPP, skin perfusion pressure; ABI, ankle-brachial index; AVEs, atherosclerotic vascular events; T1, 1st tertile; T2, 2nd tertile; T3, 3rd tertile.

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  Fig.2. Hazard ratios for composite events across the SPP and ABI quintiles in all patients. Forest plots show the HRs and 95% CIs for each quintile group. The HRs are presented in the 4th quintile as a reference. The Cox proportional hazard models were adjusted for eight covariates: sex, age, systolic blood pressure, history of AVEs and diabetes, albumin, C-reactive protein, and hemoglobin. SPP, skin perfusion pressure; ABI, ankle-brachial index; HR, hazard ratio; CI, confidence interval; ref, reference; Q1, 1st quintile; Q2, 2nd quintile; Q3, 3rd quintile; Q4, 4th quintile; Q5, 5th quintile; AVE, atherosclerotic vascular event.

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  Supplemental Fig.2. Cumulative incidence of the composite event and mortality stratified by SPP and ABI tertiles in patients with normal ABI and SPP. The cut-off points are 71 and 83 mmHg for SPP and 1.06 and 1.18 for ABI. In 215 patients with normal ABI levels, the cumulative incidences for the composite events during 5 years were 0.63, 0.40, and 0.41 with p=0.002 (A), and those for death were 0.45, 0.25, and 0.24 with p=0.025 for SPP T1, T2, and T3, respectively (B). In 230 patients with normal SPP levels, those for composite events were 0.62, 0.47, and 0.41 with p=0.041 (C), and those for death were 0.35, 0.31, and 0.32 with p=0.866 for ABI T1, T2, and T3, respectively (D). SPP, skin perfusion pressure; ABI, ankle-brachial index; AVEs, atherosclerotic vascular events; T1, 1st tertile; T2, 2nd tertile; T3, 3rd tertile.

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  Supplemental Fig.3. The incidence rate of the composite event against SPP and ABI levels in patients with normal ABI and SPP. Incidence rates were analyzed via Poisson regression adjusted for eight risk factors, as shown in Table 2, and presented using a restricted cubic spline model. The dashed lines show 95% CIs. The number of patients in the histogram is presented in the second axis. These rates were explored across SPP values in patients with a normal ABI (A) and across ABI values in patients with a normal SPP (B). Lower SPP and ABI levels were associated with a higher risk, even if ABI or SPP was within the normal range. SPP, skin perfusion pressure; ABI, ankle-brachial index; CI, confidence interval