Decision tree prediction of saline infusion test outcomes in suspected primary aldosteronism: a multicenter common data model study

초록

Context Confirmatory aldosterone suppression testing is widely utilized following positive screening for primary aldosteronism (PA), yet its incremental diagnostic value remains debated. While the 2025 Endocrine Society guideline proposes a probability-based approach, validated tools to translate this concept into clinical decision-making, particularly in Asian populations, are lacking. Methods Using a multicenter common data model across 3 tertiary hospitals (2002-2020), we retrospectively identified 307 patients who underwent saline infusion test (SIT) for suspected PA. Saline infusion test positivity was defined as postinfusion plasma aldosterone concentration (PAC) >= 10 ng/dL. We developed a conditional inference classification tree using screening-stage variables and compared its performance with conventional rigid screening criteria based on PAC and the aldosterone-to-renin ratio. Results Among 307 patients (mean age 51.2 years), 153 (49.8%) were SIT positive. Saline infusion test-positive patients had higher PAC (median 32.9 vs 12.7 ng/dL, P < 0.001) and lower serum potassium levels (3.66 vs 4.02 mmol/L, P < .001). The decision tree identified a high-probability phenotype defined by PAC > 25 ng/dL and plasma renin activity <= 0.55 ng/mL/h, with an SIT positivity rate of 96.4%. In patients with a PAC of 15.7 to 25.0 ng/dL, potassium <= 3.9 mmol/L further stratified SIT positivity to 68.8%, whereas patients with PAC <= 15.7 ng/dL had a low positivity rate. The tree-derived criteria outperformed conventional cutoffs, with an accuracy of 0.85, a sensitivity of 0.83, and a specificity of 0.86, and performance remained robust in internal validation and sensitivity analyses. Conclusion A screening-stage decision tree provides clinically interpretable probabilities for SIT positivity, supporting risk-stratified confirmatory testing and selective omission in high-probability patients.

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