Risk validation of a new quantitative score for clinical control of chronic obstructive pulmonary disease: The RADAR score

Objective: Clinical control has been proposed as a composite endpoint in chronic obstructive pulmonary disease (COPD), assessable through the COPD Clinical Control Questionnaire (CCOq). A new score, derived from the CCOq, and termed as RADAR (Rescue medication, Acute exacerbations, Dyspnea, physical Activity, and Risk) has been developed. This study aimed to validate the RADAR score by analyzing its predictive value for future risk and health status. Methods: A 12-month prospective observational study was conducted in stable COPD patients. Clinical control was assessed at 3 months using both the CCOq and the RADAR score (range 0-8). Dyspnea was evaluated both adjusted and unadjusted for FEV1%. The primary outcome was time to the first composite event (emergency visit, COPD hospitalization, or all-cause mortality); the secondary outcome was the COPD Assessment Test (CAT) score at 12 months. Results: Of 265 patients enrolled (16.2% women; mean age: 68±9 years; FEV1%: 58±17), 239 completed the 3-month assessment. Among patients with RADAR scores of 0-1, 96.5% met CCOq control criteria, whereas none with scores ≥4 were classified as controlled. Patients were categorized as good (0-1), partial (2-3), or poor control (≥4). Time to composite event differed significantly across groups (p<0.001), with RADAR remaining an independent predictor after adjustment. Predictive accuracy (C-statistic) was 0.697 (adjusted) and 0.713 (unadjusted). Conclusion: The RADAR score effectively predicts clinical risk and health status, offering a practical tool for monitoring COPD and guiding clinical decisions.