The WATCH-DM integer-based risk score identifies risk of all-cause mortality in patients with type 2 diabetes: a retrospective cohort study

Background: The WATCH-DM integer-based risk score (WATCH-DM(i)) was originally developed and validated to predict heart failure (HF) hospitalization risk in patients with type 2 diabetes mellitus (T2DM). However, its potential association with all-cause mortality in patients without HF remains unclear. Objectives: This study aimed to evaluate the prognostic utility of the WATCH-DM(i) score for all-cause mortality in a real-world outpatient cohort of T2DM patients without known HF. Design: This was a retrospective observational cohort study with national mortality registry linkage performed at a single center. Methods: We analyzed data from 449 adults with T2DM enrolled in a hospital-based cohort between 2016 and 2022. The WATCH-DM(i) score was calculated according to the original published integer-based model reported by Segar et al., using clinical and laboratory parameters. Patients were stratified into four risk groups based on their score. All-cause mortality data were obtained via national linkage. Cox regression models, Kaplan–Meier survival analysis, landmark analysis, and time-dependent receiver operating characteristic curves were used to assess mortality risk. Results: Over a median follow-up of 61 months, 39 patients (8.7%) died. Each 1-point increase in the WATCH-DM(i) score was associated with a 29% higher risk of all-cause mortality (HR: 1.287, 95% CI: 1.151–1.439, p  < 0.001). Higher risk groups showed progressively greater mortality, especially after 24 months. The score demonstrated good discrimination for 5-year mortality (C-index: 0.751). Metformin use was independently associated with lower mortality risk (HR: 0.410, p  = 0.019). Conclusion: The WATCH-DM(i) score is a robust prognostic marker of 5-year all-cause mortality in T2DM patients without HF and may serve as a practical tool for risk stratification in outpatient settings.