Risk-Adjusted Adoption era
David W. Hosmer and Stanley Lemeshow popularized practical logistic regression in medicine with Applied Logistic Regression, 1989, codifying best practices for model-building, calibration, and validation of risk-adjusted prognostic scores. Peter McCullagh and John Nelder provided the Generalized Linear Models framework that underpins logistic regression, supplying the link function, estimation, and inference methods foundational to later risk-prediction tools. Mary Charlson and colleagues introduced the Charlson Comorbidity Index in the late 1980s, translating comorbidity into numeric weights that enabled standardized risk adjustment across multicenter outcomes. Frank E. Harrell Jr.'s work on model development, validation, calibration plots, and accessible software in the 1990s and early 2000s helped institutionalize logistic regression-based risk tools in quality improvement and decision support.