Alkaline phosphatase and prognosis in patients with coronary artery disease

Background: The evidence on the association between alkaline phosphatase (ALP) and prognosis of patients with coronary artery disease (CAD) is limited. The aim of this study was to assess the association of ALP with the risk of mortality or coronary events in patients with CAD. Materials and methods: The study included 5540 patients with angiography-proven CAD treated with catheter-based coronary revascularization. Baseline ALP measurements were available for analysis in all patients. Patients were divided into three groups: a group with an ALP activity in the 1st tertile (ALP ≤ 65·5 U/L; n = 1855), a group with an ALP activity in the 2nd tertile (ALP > 65·5 to 85·7 U/L; n = 1839) and a group with an ALP in the 3rd tertile (ALP > 85·7 U/L; n = 1846). The primary outcome was all-cause mortality at 3-year follow-up. Results: All-cause deaths (number [Kaplan–Meier estimates]) occurred in 443 patients: 117 (7·2%), 130 (8·1%) and 196 deaths (11·8%) among patients of the 1st, 2nd and 3rd ALP tertiles (unadjusted hazard ratio [HR] = 1·33, 95% confidence interval [CI]: 1·19 to 1·50; P < 0·001, calculated per tertile increment in the ALP activity). After adjustment in multivariable Cox proportional hazards model, ALP was independently associated with the risk of all-cause mortality (adjusted HR = 1·33 [1·18–1·51], P < 0·001, calculated per unit increment in log ALP). The multivariable model for all-cause mortality with baseline variables without ALP had a C statistic of 0·820 [0·797–0·843] which increased to 0·825 [0·804–0·849] after ALP inclusion; delta C statistic 0·005 [0·001–0·011]; P < 0·001. Conclusions: In patients with CAD, elevated ALP activity was independently associated with the risk of 3-year all-cause mortality.