A Multidimensional Disease Weighted Index (DWI) for Risk Assessment in COPD: A Proposed Conceptual Framework and Pre-Specified Validation Roadmap

Background/Objectives: Chronic obstructive pulmonary disease (COPD) is a heterogeneous condition whose prognosis is shaped by exacerbations and by cardiovascular, inflammatory and metabolic comorbidity, which staging based on forced expiratory volume in one second (FEV1) captures poorly. In this concept paper, we propose a conceptual multidimensional prognostic index, the Disease Weighted Index (DWI), together with a pre-specified programme for its derivation and validation; the work reports no model development or validation. Methods: Ten routinely available parameters were grouped into four domains: Pulmonary–Symptomatic (FEV1, COPD Assessment Test [CAT] score, exacerbation history), Cardio–Systemic (N-terminal pro-B-type natriuretic peptide [NT-proBNP], C-reactive protein, New York Heart Association [NYHA] class), Metabolic–Nutritional (glycated haemoglobin [HbA1c], body mass index) and Demographic–Exposure (age, smoking history). Each parameter was scored on a three-level ordinal scale using guideline-based cut-offs and assigned a provisional, expert-informed weight through an explicit ordinal procedure in which the authors allocated it to a tier by judgement, guided by the adjusted effect estimates reported in the literature; these weights are specifications to be re-estimated, not established prognostic contributions. The weighted sum was normalised to a 0–100 scale. No patient-level data were used. Framework: NT-proBNP received the highest provisional weight (0.16). Four provisional risk categories (low, moderate, high and very high) were defined and linked to an expert opinion-based follow-up flowchart intended for prospective testing only. The pre-specified prediction target is a 12-month composite of severe exacerbation, all-cause hospitalisation or all-cause death. Rules for scoring when parameters are unavailable, worked examples, a conceptual comparison with the BODE, ADO, DOSE, CODEX and COTE indices, and a three-phase derivation and validation roadmap aligned with the TRIPOD statement are provided. Conclusions: The DWI is a pre-validation, testable framework that integrates the pulmonary and systemic dimensions of COPD. It is a research protocol for an index, not a validated clinical tool: its predictive performance is unproven, and it should not guide individual patient management until derivation and validation, including comparison with the unweighted sum of its items and with established indices, have been completed.