Diagnosis and treatment of renovascular hypertension: a cost-benefit analysis

We sought to evaluate and compare the relative cost-benefit of Doppler sonography, MR angiography, and captopril-enhanced renal scintigraphy as techniques for predicting a patient's clinical response to renal angioplasty.

Estimations of positive and negative predictive values of baseline and captopril-enhanced renal scintigraphy and Doppler sonography examinations for predicting a favorable outcome after renal angioplasty were based on a previously published prospective study involving 74 patients who underwent this treatment. For gadolinium-enhanced MR angiography, predictive values were calculated from a subpopulation of 57 of these 74 subjects. The value of different combined strategies with these techniques for predicting clinical success after angioplasty was evaluated in this population. The costs of investigation and treatment per improved patient were calculated for each imaging technique and for combined strategies in a hypothetic 1,000-patient population with a 30% prevalence of renal artery stenosis, relying on the diagnostic performance reported in the literature for each technique in detecting renal artery stenosis.

The costs for each improved patient were $12,579 for patients selected on the basis of a positive finding on Doppler sonography (false-negative results = 12/1,000) and $10,149 for patients selected with criteria combining a positive finding on Doppler sonography with a bilateral resistive index of less than 0.75 (false-negative results = 32/1,000). Patient selection based on a positive finding on MR angiography cost $18,119 (false-negative results = 0), whereas the cost of patient selection based on a positive finding on renal scintigraphy was $12,939 (false-negative results = 29/1,000).

Doppler sonography is more cost-efficient but less sensitive than MR angiography for identifying patients with renovascular hypertension. MR angiography should be favored in hypertensive patients who are resistant to medical therapy to avoid false-negative examinations.