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

Abstract

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.

Figure 1. Percentage and Total Number of Hot Flash Events Recorded By Monitor Only, Monitor with Concurrent Event Button, and Event Button Only

This figure shows the percentage of hot flash events that were recorded with the objective hot flash monitor only, the monitor with event button, and the event button only. Data for all four time points are shown. The figure above indicates that approximately 70% of hot flashes were recorded with the monitor (black plus grey), whereas only 50% were recorded with the event button (white plus grey).

Figure 2. Mean Hot Flash Frequency at Each Time Point

This figure shows the mean number of hot flashes with standard deviation bars for all three hot flash frequency measures (monitor, diary, event button) and at each time point. At baseline, there were no significant differences among measures. At one month, monitor frequency was significantly higher than diary and event button frequency. At three months, monitor frequency was significantly higher than event button frequency. At six months, monitor and diary frequency were significantly higher than event button frequency. Note the large standard deviation bars for each measure at each time point.

Figure 3. Hot Flash Intensity and Bother Over Time

This figure shows mean hot flash intensity and bother with standard deviation bars at each time point. Intensity and bother did not significantly change over time. Women rated intensity and bother of each hot flash using separate 0 to 10 point numeric rating scales (not at all to extremely intense or extremely bothersome). Mean intensity and bother during the 24-hour monitoring sessions at each time point were calculated for each woman. The figure shows the mean of the means.