Methods: We analyzed baseline and post-randomization patient-reported data pooled across three randomized trials aimed at reducing hot flashes in 899 midlife women. Trials were conducted across five clinical sites between July 2009 and October 2012 as part of a United States National Institutes of Health funded research network. We eliminated HFRDIS items based on experts’ content validity ratings and confirmatory factor analysis. We established cutpoints and minimally important differences by mapping HFRDIS and HFI to symptom and quality of life measures including daily diary-reported hot flashes, the Menopause Quality of Life Scale, Pittsburgh Sleep Quality Index, Insomnia Severity Index, and Generalized Anxiety Disorders-7 questionnaire.
Results: The short HFI consisted of 3 items related to interference with sleep, mood, and concentration. The HFI demonstrated strong internal consistency (alphas of 0.830 and 0.856), showed good fit to the unidimensional “hot flash interference factor”, and strong convergent validity with HFRDIS scores, diary-recorded hot flashes, and menopausal quality of life. For both scales, cutpoints of mild (0–3.9), moderate (4–6.9), and severe (7–10) were associated with increasing sleep and anxiety problems as expected. The average minimally important difference for HFRDIS was 1.66 and for HFI it was 2.34.
Conclusion: The HFI is a brief assessment tool that will be useful in busy clinical practices to standardize hot flash assessment or in research studies where response burden may be an issue. The scale cutpoints and MIDs should prove useful in targeting those most in need of treatment, monitoring treatment response, and interpreting existing and future research findings.