Is a shorter hot flash diary just as good as a 7-day diary?

In randomized trials, the most common way to measure the effect of treatment on the frequency and severity of menopausal hot flashes is a 7-day self-reported diary. However, adherence with completing the hot flash diary in real time may be poor, and completing a diary is cumbersome for study participants. Our objective was to determine if a shorter diary for recording self-reported hot flashes is as accurate and precise as the traditional 7-day diary.

Using cross-sectional data from a multicenter randomized clinical trial of an herbal preparation (MF101, an estrogen receptor beta-selective agonist for treatment of menopausal hot flashes), we compared findings based on shorter diaries with findings based on a 7-day diary.

With 3 days of diary keeping, the mean number of hot flashes per day and mean severity were almost identical to the means based on the 7-day diary, the SDs of the means were almost identical, and the intraclass correlations were almost perfect. The difference in the mean number of hot flashes per day compared with the 7-day diary was only 12% of one hot flash. Data from a different clinical trial revealed similar correspondence between the findings of a 3- and 7-day diary.

In our study, the optimal duration of diary keeping to record menopausal hot flashes seems to be 3 days. In addition to being as good as a 7-day diary, a 3-day diary would be less burden on study participants and research staff and less expensive.