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Contact: Jon Meerdink ([email protected])

ANN ARBOR — A meta-analysis of 150 empirical studies on the cardiac symptoms of COVID-19 has found that higher-quality studies report a lower prevalence of long-term cardiac symptoms.

“Identifying patterns of reported findings on long-term cardiac complications of COVID-19: a systematic review and meta-analysis” was published this month in BMC Medicine. The paper finds that while there are still long-term cardiac issues associated with COVID-19, their prevalence may be different than was previously understood.

Chihua Li, Dr.P.H., and Grace Noppert, Ph.D., both affiliated with the University of Michigan’s Institute for Social Research, worked on the paper. Li says these findings demonstrate the need for better-designed studies on long-term COVID-19 symptoms.

“Studies with higher quality report lower prevalence of long-term cardiac symptoms, while low-quality studies tend to report high levels of prevalence,” he said. “This does not mean that long-term cardiac symptoms are not important or rare. But future studies need to be better designed and more rigorous so we can have more meaningful and valid results.” 

The paper examined 150 studies of COVID-19 symptoms. Researchers initially used a Newcastle-Ottawa scale, but moved to a customized assessment tool to sort the studies into high-, medium-, and low-quality groups. Of the 150 studies in the assessment, about three quarters were of medium or high quality. 

The low-quality studies, Li said, were often victims of a limited scope in their research.

“Many were based on a single hospital or two to three hospitals. That makes them not necessarily representative of our population,” he said. “If we really want to know what the pattern looks like of long-term cardiac symptoms, or even other symptoms of COVID-19, we need a population that is representative of the whole population, either in the U.S. or other countries across the world.”

In its recommendations, the paper concludes that future studies on COVID-19 symptoms must be more conscious of their sampling habits and representation in their data.

“Specifically, we found that studies with low-quality, small sample size, unsystematic sampling method, or cross-sectional design were most likely to report a higher prevalence of complications among individuals who survived COVID-19,” the research team wrote. “We believe that a deeper understanding of long COVID is currently prevented by the limitations of the published literature. Our study underscores the need to conduct high-quality studies on long COVID and the importance of long-term cardiac surveillance of COVID-19 survivors.”

The full text of the paper is available via BMC Medicine.