SPECT myocardial perfusion imaging with technetium-99m (Tc99m) shows normal findings. Source: Daniel S. Berman, MD, of Cedars-Sinai Heart Institute

Despite the fact that appropriate use criteria (AUC) have been developed to help guide myocardial perfusion imaging (MPI), women remain undertested. A study published this week in the Journal of Nuclear Cardiology showed that the vast majority of inappropriate MPI studies were ordered in women by primary care physicians (PCPs), alluding to the fact that more education for physicians will be crucial.

The utilization rate of MPI increased three-fold from 1993 to 2001, however, the rates of MI have remained uniform. “This raises concerns about unnecessary testing with its attendant increased cost, without clear-cut evidence of benefit,” wrote Aarti Gupta, MD, of Miriam Hospital and Rhode Island Hospital in Providence, R.I., and colleagues.

Because women are still less apt than men to receive these imaging studies, Gupta et al set out to evaluate whether gender disparities exist in tests categorized by their appropriateness and whether a physician’s specialty could be the culprit for these disparities.

To do so, Gupta and colleagues applied AUC to 314 MPI imaging studies to assess possible gender disparities. Of the 314 studies, 263 were deemed appropriate, 34 were deemed inappropriate and 17 were uncertain. Patients in the cohort who underwent MPI imaging had a mean age of 62 years; 52 percent of patients were male.

The researchers found that 68 percent of the inappropriate studies and 82 percent of uncertain studies were performed in women.

Of the 314 studies, cardiologists ordered 120 studies and PCPs ordered 194 studies. Gupta and colleagues found that cardiologists ordered more appropriate studies when compared with PCPs in women, 92 percent versus 79 percent. Of the 17 studies deemed uncertain, cardiologists ordered one and PCPs ordered 16.

A greater number of appropriate MPI studies were performed in men compared with women, 96 percent versus 86 percent. For men, there was no difference between the percentage of appropriate studies ordered by cardiologists or PCPs.

Gender reversal demonstrated disparities within the AUC tool. The researchers found that 15 percent did not correlate. However, 8 percent of studies would go from appropriate to inappropriate and 7 percent would go from inappropriate to appropriate. The authors noted that “utilizing a different tool for pre-test risk assessment of the symptomatic patient may allow more accurate assignment of women into one of the three AUC categories.”

The researchers also calculated the relative risk of being classified as inappropriate or uncertain based on gender. Results showed that women undergoing SPECT MPI had a relative risk of 2.69 that the test would be classified as inappropriate and a 6.00 relative risk that the test would be uncertain compared with men.

“The AUC were created to help guide the use of SPECT MPI in an era where use of nuclear imaging has increased astronomically. AUC are based on existing data and expert panel deliberation. However, the AUC are not widely used and there is currently a lack of data on how implementation has affected clinical practice,” the authors wrote.

Gupta and colleagues speculated that the higher number of tests deemed inappropriate by PCPs could be due to the fact that these physicians treat lower-risk patients compared to cardiologists. However, they said that cardiologists may have a greater understanding of the AUC and its application in clinical practice.

Gupta et al concluded that gender disparities within SPECT MPI are a major hurdle to clinical care and said that more education is needed for PCPs so that they are able to more appropriately utilize SPECT MPI in concordance with AUC, especially as they applies to women.