Candidate for the Lee B. Lusted Student Prize Competition
Purpose: Patients with primary aldosteronism (PA) comprise 17-23% of the resistant hypertensive population. Consensus guidelines for the screening and diagnosis of unilateral PA vary. We aimed to identify cost-effective strategies, including the use of CT and adrenal venous sampling (AVS), for identifying surgically correctable PA patients.
Method: A decision-analytic model (TreeAge 2009 Software, Williamstown, MA) was used to compare the costs (testing, imaging, surgery, and discounted life-time costs of spironolactone to treat non-surgical PA) and effectiveness (SBP reduction) of six screening and lateralization (i.e. identification of surgically correctable PA) strategies for PA in 55-year-old resistant hypertensive patients with and without the use of confirmatory saline-infusion test (SIT, following positive screening aldosterone to renin ratio), abdominal CT, and/or adrenal venous sampling (AVS). Patients diagnosed with unilateral PA underwent laparoscopic adrenalectomy; patients identified to have PA but who did not lateralize were given spironolactone. Estimates of differential changes in SBP for patients undergoing surgery or adding spironolactone and for those with PA versus non-PA resistant hypertension were based on prospective data from the literature. Costs were based on 2011 Medicare reimbursement schedules and Red Book: PDR. The primary outcome was cost (2011 US$) per change in SBP (mmHg). Sensitivity analyses were performed.
Result: Strategies with AVS strongly dominated strategies without AVS (Table 1). Three AVS strategies were on the efficient frontier. Although no conventional willingness to pay threshold for cost per change in SBP exists, proceeding to AVS following a positive screen for PA is cost-effective at a threshold of $1661.39 per mmHg or more. The strategies on the efficient frontier were stable across ranges of effectiveness (changes in SBP) and diagnostic accuracy.
Conclusion: Of the tested surgical strategies, proceeding directly to lateralization with AVS from a positive screening test yields the most SBP reduction, but a strategy of using CT prior to AVS was also efficient. Given that PA patients have increased reversible cardiovascular risks and decreased quality of life in comparison to matched non-PA hypertensive patients, changes in SBP will likely have a greater impact on PA patients. Further modeling should explore the lifetime secondary differential effects of continued hypertension in PA patients, comparisons of surgical strategies to medical therapy alone, and differential health-related quality of life of medical versus surgical strategies. 