Baseline shock index-creatinine clearance score and long-term mortality after ACS. Results from 24 years of follow-up of the ABC study on heart disease

Abstract Background Shock Index-Creatinine Clearance score (SI-C) is an updated version of the shock index that includes renal function. Recent studies reported its potential as a novel and simple risk stratification tool for predicting in-hospital mortality in acute coronary syndrome (ACS) patients. Purpose To assess the long-term predictive value of baseline SI-C score in patients after ACS. Methods This preliminary prospective analysis included 589 patients with ACS admitted to three Italian hospitals and discharged alive. Baseline clinical and laboratory data were collected within the first 7 hospitalization days and baseline SI-C score was calculated as [(SI×100)-estimated creatinine clearance]. Patients were prospectively followed for 24 years or until death. Results Virtually all patients completed the follow-up, representing 7066 person-years. Patients' mean age was 66±12 years, 70% were males, and 482(82%) had died during follow-up. Compared to those who survived, deceased patients were significantly different in many of the baseline clinical characteristics. They also showed a significantly higher SI-C values ( -11± 25 vs. -36±23, p<0.0001). The predictive value of SI-C for 24-year mortality was very good (area under the curve= 0.783, 95% CI: 0.738-0.827, p<0.001). The cumulative risk was significantly higher in the upper SI-C tertile (log-rank = 162.1, p < 0.001). Unadjusted Cox regression survival analysis showed that the SI-C score was significantly associated with long-term all-cause mortality (HR: 2.1, 95%CI 1.8-2.3, p<0.0001). Similar results were obtained with the fully adjusted model. Conclusion Baseline SI-C seems to be an effective and independent predictor of long-term all-cause mortality after ACS.