Lifestyle changes may lower risk
The message is that “young women with long or irregular menstrual cycles may benefit from lifestyle changes to reduce the risk of NAFLD,” Dr. Ryu stated.
The Study of Women’s Health Across the Nation, which was started in 1994, has not evaluated NAFLD, but it did show a relationship between longer menstrual cycles and more cardiometabolic risk factors, according to Nanette Santoro MD, professor and chair, department of obstetrics & gynecology, University of Colorado at Denver, Aurora.
Dr. Nanette Santoro
This suggests that others are “thinking along the same lines,” but in discussing this study with this news organization, she characterized some of the design elements as well as some of the findings in this study as “peculiar.”
In addition to a “very, very narrow definition of regular cycles,” she questioned the consistent hazard ratio for NAFLD for those with long cycles relative to other types of irregular menses. Presuming that the group with longer cycles would have included at least some patients with undiagnosed PCOS, she was would have expected that the risk would have been highest in this group. While conceding that differences in body composition of Korean women is a potential explanation for this apparent discrepancy, “I would like to see confirmed in other samples of women with more detailed metabolic assessments to understand who is at risk,” she said.
Not least problematic for the strength of the conclusions, the hazard ratio for NAFLD among women with long or irregular menstrual cycles was “pretty low.” She described this as a level at which the risk “is very susceptible to confounding and unlikely to influence clinical practice.”
Anuja Dokras, MD, PHD, a professor of obstetrics and gynecology and director of the PCOS Center at the University of Pennsylvania, Philadelphia, also questioned whether undiagnosed PCOS might have skewed the data.
“There is increasing data on the association between PCOS and NAFLD. Irregular menses is a key criterion for PCOS, and PCOS is the commonest reason for anovulation,” she said. Dr. Dokras therefore considered it possible that patients with unrecognized PCOS were included in the study, weakening the claim that risk of NAFLD and long menstrual cycles remains significant after controlling for PCOS.
Dr. Ryu and coinvestigators, Dr. Santoro, and Dr. Dokras reported no potential conflicts of interest.