Comparison of subjective and objective hot flash measures over time among breast cancer survivors initiating aromatase inhibitor therapy

Objective: Hot flashes are valuable indicators of physiological condition and drug effect; however, subjective and objective measures do not always agree. No study has examined both subjective and objective hot flashes in women prescribed aromatase inhibitors. The study (1) compared subjective and objective hot flash measures, (2) examined changes in subjective and objective hot flashes over time, and (3) evaluated predictors of change in hot flashes in aromatase inhibitor-treated women. Methods: Participants (n = 135) were enrolled in a randomized clinical trial comparing exemestane and letrozole for the treatment of breast cancer. Hot flashes were assessed before the start of the drug therapy and 1, 3, and 6 months later. Participants wore a sternal skin conductance monitor for 24 hours or longer at each time point. With each perceived hot flash, women pressed an event button and rated intensity and bother in a paper diary. Results: Participants had a mean age of 60 years and were mainly white (92%). Across time points, monitor hot flashes were (1) significantly more frequent than diary and/or event button flashes (P < 0.05) and (2) moderately correlated with subjective measures (0.35 < r < 0.56). Monitor hot flashes did not significantly change over time with aromatase inhibitor therapy, whereas both diary and event button frequencies significantly varied but in dissimilar patterns (51% nonlinear). No consistent predictors of hot flashes across measures or time points were identified. Conclusions: Findings indicated dissimilarities between subjective and objective measures of hot flashes. Despite statistical significance, there was little clinically meaningful change in hot flashes after initiating aromatase inhibitor therapy.