Cost-Effectiveness Analysis of Age-Specific N-Terminal Pro-B-Type Natriuretic Peptide Thresholds for Heart Failure Diagnosis in China: Protocol for a Markov Model–Based Study

Background Heart failure (HF) imposes a substantial clinical and economic burden in China. Although N-terminal pro-B-type natriuretic peptide (NT-proBNP) is widely used in the diagnostic pathway for HF, conventional thresholds are largely derived from Western populations and may not be fully applicable to Chinese adults. Objective This study aims to evaluate the cost-effectiveness of an exploratory age-specific NT-proBNP threshold strategy compared with a conventional universal threshold strategy for HF diagnosis in China. Methods We developed a hybrid decision-analytic model linking an initial diagnostic decision tree to long-term Markov state-transition pathways. The target population comprised adults aged ≥45 years with symptoms suggestive of HF who underwent further clinical diagnostic evaluation. The China Health and Retirement Longitudinal Study was used to inform the baseline demographic and comorbidity structure. Two diagnostic strategies were compared: (1) an exploratory age-specific NT-proBNP strategy using thresholds of 100 ng/L for individuals aged <65 years and 248 ng/L for those aged ≥65 years and (2) a conventional threshold strategy using 125 ng/L as the comparator cutoff. The analysis was conducted from the perspective of the Chinese health care system. Primary outcomes included direct medical costs, quality-adjusted life-years, and incremental cost-effectiveness ratios. The base-case analysis used a 10-year time horizon, with annual discounting of 5% for both costs and health outcomes. Parameter uncertainty will be assessed using deterministic sensitivity analysis, probabilistic sensitivity analysis with 5000 Monte Carlo simulations, and scenario analyses. Results This study was funded in January 2025. Model construction has been completed, and parameter collection, calibration, and validation are ongoing. The final cost-effectiveness analysis is expected to be completed after project-specific Chinese data become available. Planned outputs include total costs, quality-adjusted life-years, incremental cost-effectiveness ratios, diagnostic classification outcomes, and cost-effectiveness acceptability results. Conclusions This protocol will assess whether age-specific NT-proBNP thresholds provide economic or clinical advantages over a conventional universal threshold strategy in the Chinese health care setting. The findings are intended to inform future diagnostic policy while explicitly acknowledging uncertainty surrounding the exploratory age-specific thresholds and other structural assumptions. International Registered Report Identifier (IRRID) PRR1-10.2196/95071