Frequent vasomotor symptoms (VMS) associated with menopause persist longer than had been thought, and the sooner they start, the longer they last, according to a study published online February 16 in JAMA Internal Medicine. The longest duration of VMS occurred among black women.

Up to 80% of women experience VMS, and many seek relief. The duration of VMS affects healthcare decisions, such as when to begin and how long to undergo hormone replacement therapy. Many sources of information for patients state that hot flashes and night sweats last 3 to 5 years. Clinical guidelines maintain that most women experience VMS for 6 months to 2 years, but anecdotal reports as well as epidemiologic studies place the duration at up to 13 years.

To more accurately assess the duration of VMS in women traversing menopause, Nancy E. Avis, PhD, a professor of public health sciences–social sciences at Wake Forest Baptist Medical Center in Winston-Salem, North Carolina, and coauthors analyzed data from 1449 women with frequent VMS (6 or more affected days in the previous 2 weeks). They obtained data from the Study of Women's Health Across the Nation (SWAN), a multiracial/multiethnic observational study of women entering menopause conducted from February 1996 through April 2013.

The women were evaluated at a median of 13 visits during SWAN. The current study focused on frequency of events because this is the characteristic of menopause women identify as the most disturbing.

The researchers established two primary outcomes: "Total VMS duration" indicated the years elapsed between the first and last report of frequent VMS, and "Post-FMP persistence" indicated the number of years that frequent VMS persisted after the final menstrual period (FMP). The researchers defined cessation of VMS as two consecutive visits without hormone replacement therapy or experiencing VMS.

The investigation also sought to identify risk factors for the two measures.

The study goes beyond others by extending analysis past the FMP.

The median total duration of VMS was 7.4 years. Among 881 women who were aware of their FMP, the median post-FMP persistence was 4.5 years.

Timing of menopause emerged as an important factor in the duration of VMS. The longest total VMS duration (median, >11.8 years) and post-FMP persistence (median, 9.4 years) occurred among women who were premenopausal or early perimenopausal when they first experienced frequent VMS. Women who were postmenopausal when VMS began had the shortest total VMS duration (median, 3.4 years).

Black women experienced the longest total VMS duration (median, 10.1 years). Japanese and Chinese women reported the shortest VMS duration (median, 4.8 years and 5.4 years, respectively). The median total VMS durations were 6.5 years for non-Hispanic white women and 8.9 years for Hispanic women.

Longer VMS duration was associated with younger age, lower educational level, history of smoking, greater perceived stress, greater sensitivity to symptoms, and depression and anxiety at the time of the first report of VMS. Shorter VMS duration was noted among women with partners, higher educational level, less financial pressure, and greater social support.

"These findings can help health care professionals counsel patients about expectations regarding VMS and assist women in making treatment decisions based on the probability of their VMS persisting. In addition, the median total VMS duration of 7.4 years highlights the limitations of guidance recommending short-term [hormone therapy] use and emphasizes the need to identify safe long-term therapies for the treatment of VMS," the authors conclude.

A limitation of the study is that the 2-week snapshot of VMS pattern, although standard for such investigations, may have missed symptom onset in some women. In addition, the study length was 13 years, which would not have captured women who have VMS for longer.

In an invited commentary, Gloria Richard-Davis, MD, and JoAnn E. Manson, MD, DrPH, from the Division of Preventive Medicine and Department of Epidemiology at Brigham and Women's Hospital in Boston, Massachusetts, review the implications of the findings on treatment of VMS. They point out that women at the beginning of menopause may in fact still be fertile, and if they experience frequent VMS, low-dose combined oral contraceptives may protect them from pregnancy while tempering the hot flashes and drenching night sweats.

The longer timeframe for menopause may also encourage some women to seek nonhormonal treatments for managing VMS symptoms, such as antidepressants (certain selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors) recently approved by the US Food and Drug Administration for this indication, gabapentin, pregabalin, clonidine, and complementary and alternative methods.

Dr Richard-David and Dr Manson conclude that the new study overturns the dogma of short-duration VMS with minimal effects on health and quality of life. "The study by Avis et al contributes important information to facilitate a more personalized and informed approach to decision making and clinical care for midlife women," they write.

The investigators and commentators have disclosed no relevant financial relationships.

JAMA Intern Med. Published online February 16, 2015. Article abstract, Commentary extract