To investigate factors associated with the presence, severity, and frequency of hot flushes.
A 9-year prospective study of 438 Australian-born women, aged 45 to 55 years and menstruating at baseline. Annual fasting blood collection, physical measurements, and interviews including questions about bothersome hot flushes in previous 2 weeks were performed. A "hot flush index" score was calculated from the product of the severity and frequency data. Data were analyzed using random-effects time-series regression models.
A total of 381 women supplied complete data over the follow-up years. A total of 350 women experienced the menopause transition, of whom 60 (17%) never reported bothersome hot flushes. At baseline, women who reported hot flushes were significantly more likely to have higher negative moods, not be in full- or part-time paid work, smoke, and not report exercising every day. Over the 9-year period of the study, variables significantly associated with reporting bothersome hot flushes were relatively young age (P < 0.001), low exercise levels (P < 0.05), low estradiol levels (P < 0.001), high follicle-stimulating hormone (FSH) levels (P < 0.001), smoking (P < 0.01), being in the late menopause transition (P < 0.001), or being postmenopausal (P < 0.001). In women reporting hot flushes, the hot flush index score increased as their FSH levels increased (P < 0.01), as they entered the late stage of the menopause transition (P < 0.001), and as they became postmenopausal (P < 0.05), and decreased with as their age (P < 0.001) and exercise level (P < 0.05) increased. Between-women analyses found that the hot flush index score was greater in women with higher average FSH levels over time (P < 0.05).
Menopause status, FSH and estradiol levels, age, exercise level, and smoking status all contributed to the experience of bothersome hot flushes.