Clinical trials and registries often are skewed in a whole variety of ways, and some of the more radical kinds are being revealed in the data from the ICD registry just released by the Heart Rhythm Society (HRS; Washington).

Perhaps the largest is that 74% of those implanted are men.

Given recent publication of gender differences in the way heart disease is presented in men and women, different types and rates of treatment for men and women, this three-to-one differential is thought-provoking, Stephen Hammill, MD, acknowledges.

Hammill, chair of the steering committee for the registry, called this chunk of data “striking” and that it raises a variety of questions. It is an issue to be explored further with additional analysis and continuing data collection.

“We will compare this database with the databse that the AHA [American Heart Association] has put together. We’re looking at all patients who have cardiac problems to try to get an idea if the increased number in men means that more men have heart disease or if there really is a different in the threshold for implantation.

Hammill said that one clear goal of the ICD registry to “to point out these types of issues in the real-life application of [ICD] therapy, to then trigger further research, and that’s what this is doing with gender.

“We will have to compare this database with a database that the AHA has put together, looking at all patients who have cardiac problems, to try to get an idea if the increased number in men means more men have heart disease or if there really is a difference in the threshold for implantation.”

As to ethnicity, 83% of those implanted were white.

He pointed out that another large skewing factor seen in the data is the difference in age between Medicare and non-Medicare patients receiving ICDs — an average of 74 years, vs. an average of 60 years, with the total average of 68 years old.

“After we told [the hospitals] about this difference, most of the hospitals” — 88% — “chose to provide data for both groups of patients,” he said.

— Don Long

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