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Hot flash clinical trial baseline measurements: how long is needed?
  1. Daniel S Childs1,
  2. Paul J Novotny2,
  3. Paulina S Marell3,
  4. Kathryn J Ruddy1 and
  5. Charles L Loprinzi1
  1. 1Oncology, Mayo Clinic, Rochester, Minnesota, USA
  2. 2Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota, USA
  3. 3Medicine, Mayo Clinic, Rochester, Minnesota, USA
  1. Correspondence to Dr Daniel S Childs, Oncology, Mayo Clinic, Rochester, MN 55902, USA; childs.daniel{at}


Objectives Classically, hot flash studies included a baseline period of 1 week or longer. The objective of this study was to compare the accuracy of a 1-day baseline diary to a traditional 1-week diary.

Methods Raw data from 5 pilot studies and 15 phase III randomised controlled trials (RCTs), all of which used a 1-week baseline period, were obtained. Descriptive statistics were used to describe day-by-day variations in hot flash frequencies and scores, during the baseline week. Additional analyses evaluated whether the conclusions from any of the individual pilot studies would have been changed if only a 1-day baseline period had been used. For the RCTs, p values were recalculated using mixed models, adjusting for the baseline value by including it as a covariate.

Results A total of 2573 participants were included. On average, participants had 8.5 hot flashes per day on day 1. Mean hot flash frequencies and scores on subsequent days (days 2–7) were within 6% of day 1 values. When comparing a 1-day to a 1-week baseline period, there was an absolute difference of only 0.29 hot flashes per day (SD 2.25). Reanalysis for each pilot study revealed that no individual study conclusions would have been altered by a shorter baseline. For the RCTs, a shorter baseline period changed the results of only 1 of 24 comparisons from statistically significant to not significant, or vice versa.

Conclusions A 1-day hot flash diary appears to accurately reflect the true frequency and severity of baseline symptoms in appropriately sized cohorts.

  • Breast
  • Prostate
  • Quality of life
  • Supportive care
  • Symptoms and symptom management

Data availability statement

Data are available upon request.

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  • Contributors The authors confirm contribution to the paper as follows: study conception and design: DSC, PJN, PSM, KJR, CLL; data collection: PJN, DSC; analysis and interpretation of results: DSC, PJN, PSM, KJR, CLL; draft manuscript preparation: DSC, CLL. All authors reviewed the results and approved the final version of the manuscript. DSC and CLL acting as guarantors.

  • Funding This study was supported by the Breast Cancer Research Foundation (BCRF-21-103).

  • Competing interests CLL reports personal fees from PledPharma, personal fees from Disarm Therapeutics, personal fees from Asahi Kasei, personal fees from Metys Pharmaceuticals, personal feesfrom OnQuality, personal fees from Mitsubishi Tanabe, personal fees from NKMax, personal fees from Novartis, personal fees from HengRui, personal fees from Nuro Bio, and personal fees from OsmolTherapeutics, outside the submitted work. The remainder of the authors report no conflicts of interest.

  • Provenance and peer review Not commissioned; internally peer reviewed.