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Date of release: 18 July, 2016

Risk parameters for duration and peak severity of hot flushes

The aim of a recent survey by Smith and colleagues was to identify risk factors associated with the duration of hot flushes and the time of peak hot flush severity in mid-life women [1]. Data were extracted from a US cohort of 647 women reporting hot flushes at baseline and followed for 1–7 years. The following risk factors were considered: menopause status, race, education, body mass index (BMI), smoking, alcohol consumption, leisure and work activity, and sex hormone levels. Average hot flush duration was 2.5 years (range 1–33 years). Peak severity (time from first experience of flush) was on average at 2.96 years (range 1–20 years). Duration of hot flushes was associated with race, education, menopause status, smoking history, BMI, alcohol consumption, leisure activity levels, and levels of estradiol and progesterone. In the final model, only race, alcohol consumption and menopause were retained. White women had significantly shorter hot flush durations than non-white women. Women consuming at least 12 alcoholic drinks in the previous year had a significantly shorter duration of hot flushes with a smaller effect of hot flush duration on increasing in time to peak severity compared to those who consumed less than 12 alcoholic drinks in that year. Higher serum progesterone levels were associated with later peak severity if the duration of the hot flushes was less than 2 years and an earlier peak severity otherwise.

Comment

This study brings some new insights on the dynamics of hot flushes, as the existing knowledge on the relevant risk factors for longer duration or time to peak severity is limited. As previously described, non-white women (primarily African-American women) were more likely to have hot flushes than white women, which could be the result of higher BMIs or different estradiol levels. In a recent publication from the SWAN study, women with greater BMI had longer total vasomotor symptom (VMS) duration; however, BMI was no longer significantly associated with total symptom duration in multivariable models when considering factors such as race/ethnicity [2]. Smith and colleagues' study [1] did show the importance of other known risk factors, such as education, smoking and physical activity on duration of hot flushes, but these were not retained in the multivariate model. The impact of drinking alcohol on hot flush duration was explored in other studies as well. In the Prospect-EPIC cohort, alcohol consumption was not associated with vasomotor symptoms after adjustment for age [3]. An overview by Ziv-Gal and Flaws concluded that no single associated factor, including alcohol consumption, was consistently identified as having a major role in experiencing hot flushes [4]. To note, in the current study the definition of alcohol consumption (less or more than 12 drinks in the previous year) seems a little strange, and I wonder why a yes/no alcohol consumption category was not used instead. As an example, a Finnish study, which did show a correlation with vasomotor symptoms, used a cut-off point of more than 16 drinks versus less than 10 drinks per week [5]. Other studies used different definitions, and thus methodology is always a major factor in the evaluation of any clinical results.

Time to peak severity was for me a somewhat innovative perspective of hot flush dynamics. In the current study, a longer duration of hot flushes delayed that peak, and a shorter duration was associated with an earlier peak, but the investigators pointed out that the biological mechanism is unclear. The influence of progesterone levels on time to peak severity may be explained by the hormonal effect on thermoregulation. A recent review summarized the role of sex hormones as follows [6]: 'Estrogens tend to promote lower body temperatures via augmentation of heat dissipation responses, whereas progesterone tends to promote higher body temperatures. Recent evidence suggests specific influences of estrogens on central autonomic nuclei involved in control of skin blood flow and sweating. Estrogens also augment vasodilation by direct effects on peripheral blood vessels. Influences of progesterone are less well understood, but include both centrally regulated changes in thermoregulatory set-point as well as peripheral effects, including augmented vasoconstriction in the skin.'

To conclude, it appears that some features of hot flushes, a very common and disturbing symptom of menopause, are not yet fully understood and probably await further investigation.

Comentario

Amos Pines


Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel



    References

  1. Smith RL, Gallicchio L, Miller SR, Zacur HA, Flaws JA. Risk factors for extended duration and timing of peak severity of hot flashes. PLoS One 2016;11:e0155079


    http://www.ncbi.nlm.nih.gov/pubmed/27149066

  2. Avis NE, Crawford SL, Greendale G, et al. Duration of menopausal vasomotor symptoms over the menopause transition. JAMA Intern Med 2015;175:531-9


    http://www.ncbi.nlm.nih.gov/pubmed/25686030

  3. van den Berg MJ, Herber-Gast GC, van der Schouw YT. Is an unfavourable cardiovascular risk profile a risk factor for vasomotor menopausal symptoms? Results of a population-based cohort study. BJOG 2015;122:1252-8


    http://www.ncbi.nlm.nih.gov/pubmed/25515605

  4. Ziv-Gal A, Flaws JA. Factors that may influence the experience of hot flushes by healthy middle-aged women. J Womens Health (Larchmt) 2010;19:1905-14


    http://www.ncbi.nlm.nih.gov/pubmed/20831431

  5. Moilanen J, Aalto AM, Hemminki E, Aro AR, Raitanen J, Luoto R. Prevalence of menopause symptoms and their association with lifestyle among Finnish middle-aged women. Maturitas 2010;67:368–74


    http://www.ncbi.nlm.nih.gov/pubmed/20869181

  6. Charkoudian N, Stachenfeld N. Sex hormone effects on autonomic mechanisms of thermoregulation in humans. Auton Neurosci 2016;196:75-80


    http://www.ncbi.nlm.nih.gov/pubmed/26674572