Objective: To compare 2 subjective and 1 objective method for assessing hot flush frequency: prospective paper hot flush diaries, prospective electronic event markers, and the Biolog ambulatory sternal skin conductance monitor.
Methods: Fifty-five breast cancer survivors provided two 24-hour periods of data, 1 week apart, at baseline before being randomized for an intervention study. Women completed a prospective paper hot flush diary and pressed an event marker to subjectively record each hot flush they experienced while wearing a sternal skin conductance monitor.
Results: Sensitivity was uniformly low (< 50%) for both subjective methods at each week. The estimated probability that a woman would record a true monitor-verified hot flush subjectively by diary or event marker was between 36% and 50% of the time if she was awake and between 22% and 42% of the time if she was asleep. Underreporting of diary hot flushes consequently resulted in more than 50% missing severity and bother ratings. Specificity was high (96-98%) for both the diary and event marker, for both weeks, and for both waking and sleeping times. The positive predictive value was low (34-52%), and negative predictive value was high (94-97%). This indicates that, rather than overreporting hot flushes when they did not exist, women tended to underreport hot flushes when they did exist.
Conclusion: Use of prospective paper hot flush diaries and electronic event markers may seriously underestimate hot flush frequency and result in missed intensity and bother ratings.