Classic risk factors?
Dr. Seeland praised the fact that the study authors tried to determine the role that classic cardiovascular risk factors played. “Compared with women with a regular cycle, women with an irregular cycle had a higher BMI, more frequently increased cholesterol levels, and an elevated blood pressure,” she said. Women with a long cycle displayed a similar pattern.
It can be assumed from this that over a woman’s life span, BMI affects the risk of cardiovascular disease. Therefore, Dr. Wang and coauthors adjusted the results on the basis of BMI, which varies over time.
Regarding other classic risk factors that may have played a role, “hypercholesterolemia, chronic high blood pressure, and type 2 diabetes were only responsible in 5.4%-13.5% of the associations,” wrote the researchers.
“Our results suggest that certain characteristics of the menstrual cycle across a woman’s reproductive lifespan may constitute additional risk markers for cardiovascular disease,” according to the authors.
The highest rates of cardiovascular disease were among women with permanently irregular or long cycles in early to mid adulthood, as well as women who had regular cycles when younger but had irregular cycles in mid adulthood. “This indicates that the change from one cycle phenotype to another could be a surrogate marker for metabolic changes, which in turn contribute to the formation of cardiovascular diseases,” wrote the authors.
The study was observational and so conclusions cannot be drawn regarding causal relationships. But Dr. Wang and associates indicate that the most common cause of an irregular menstrual cycle may be PCOS. “Roughly 90% of women with cycle disorders or oligomenorrhea have signs of PCOS. And it was shown that women with PCOS have an increased risk of cardiovascular disease.”
They concluded that “the associations observed between irregular and long cycles in early to mid-adulthood and cardiovascular diseases are likely attributable to underlying PCOS.”
For Dr. Seeland, however, this conclusion is “too monocausal. At no point in time did there seem to be any direct information regarding the frequency of PCOS during the data collection by the respondents.”
For now, we can only speculate about the mechanisms. “The association between a very irregular and long cycle and the increased risk of cardiovascular diseases has now only been described. More research should be done on the causes,” said Dr. Seeland.
This article was translated from the Medscape German edition. A version of this article first appeared on Medscape.com.