Cost and clinical consequences of stress/single-photon emission computed tomography testing with specific medications

We identified the cost of care and clinical events using dipyridamole versus adenosine in pharmacological stress (ST)/single-photon-emission computed tomography (SPECT) myocardial perfusion testing.

Commercial health plan members received adenosine or dipyridamole as an adjunct to ST/SPECT testing during the period January 1, 2006, through November 30, 2008. Propensity score matching techniques were used to compare risk-adjusted, test-related complications, symptoms and costs.

A total of 12,351 patients underwent ST/SPECT testing with dipyridamole and 59,969 with adenosine. Risk-adjusted outcomes analysis showed that patients receiving dipyridamole had a higher number of emergency room (ER) visits (0.65 vs. 0.23%, p<0.001) and angina pectoris episodes (7.11 vs. 6.01%, p<0.001). The likelihood of shortness of breath was significantly higher (6.63 vs. 5.77%, p<0.001) in the adenosine group. One-day risk-adjusted, office-visit, outpatient hospital and other utilization costs for same day ST/SPECT testing were higher for the adenosine group. Risk-adjusted ER visit costs were higher for the dipyridamole group ($1276 vs. $1095, p<0.001).

First the presence of a claim for a filled prescription does not indicate that the medication was consumed or taken as prescribed. Second, medications filled over-the-counter or provided as samples will not be observed in the claims data. Third, presence of diagnosis codes on medical claims are not positive presence of disease, as diagnosis codes may be incorrectly coded or included as rule-out criteria rather than actual disease. Finally, certain information is not readily available in claims data that could have an effect on study outcomes, such as certain clinical and disease-specific parameters.

Differences in complications and symptoms may help identify a better-tolerated vasodilator drug (VD) for use in pharmacologic stress testing based on a patient's history and symptoms. Implementation of a data-based strategy for the selection of the most appropriate stress-testing adjunctive agent may be a cost-effective step for institutions and health plans.