The prevalence of primary aldosteronism (PA) is estimated to be approximately 20% among patients with resistant hypertension, yet global screening rates remain below 1%. PA is associated with increased cardiovascular risk. Guidelines recommend screening of patients with resistant, hypokalemic, or young-onset hypertension, and patients with adrenal nodules or a relevant family history. International studies show that PA screening is cost-effective and sometimes cost-saving, but its cost-effectiveness in Singapore is unknown.

A cost-utility analysis was conducted from the healthcare system perspective, using a base case of a 40-year-old patient with hypertension. A hybrid framework combined a diagnostic decision tree with a lifetime Markov model to estimate health and economic outcomes. Four strategies were compared: (1) current practice (1% of high-risk tertiary patients screened), (2) all high-risk tertiary patients screened, (3) all high-risk primary care patients screened, and (4) universal screening of all hypertensive primary care patients. Costs were informed by hospital records, published data, and expert opinion. Outcomes were expressed in quality-adjusted life years (QALYs), with a willingness-to-pay threshold of SGD $75,000 per QALY.

Compared to current practice, universal screening (Strategy 4) achieved the greatest lifetime health gain of 7.17 QALYs per patient at an incremental cost of SGD 6,798. This yielded an incremental cost-effectiveness ratio (ICER) of SGD 12,908/QALY and the highest net monetary benefit (SGD 509,978). Screening all high-risk patients in primary care (Strategy 3) offered a marginally lower health gain of 6.65 QALYs and also with a much lower ICER of SGD 5,399/QALY. Over shorter time horizons (10- and 20- year models), Strategy 4 remained optimal except at 10 years, where Strategy 3 was most cost-effective (ICER SGD 9,706/QALY). Probabilistic sensitivity analysis showed that universal screening had the highest probability (>75%) of being cost-effective at the WTP of SGD 75,000/QALY.

Universal PA screening among hypertensive patients in primary care represents the most cost-effective long-term approach for Singapore. In contexts where budgets are constrained or short-term planning predominates, focusing on high-risk groups may provide a more practical alternative.