Daily diaries vs retrospective questionnaires to assess asthma control and therapeutic responses in asthma clinical trials: is participant burden worth the effort?

BACKGROUND: Presently, there is insufficient information to compare the value of daily diaries vs retrospective questionnaires for assessing symptoms in relationship to asthma control in clinical trials. Daily symptom diaries are often burdensome to gather, incomplete, susceptible to fabrication, and of questionable reliability. There is also concern that retrospective symptom questionnaires may be subject to poor recall and may be insensitive.
METHODS: To compare these two methods of assessing symptoms reporting, we analyzed data collected during the Best Add-on Therapy Giving Effective Responses (BADGER) trial. During the trial, asthma control in 182 children aged 6 to 17 years was assessed in two ways: (1) by asthma control days (ACDs) determined by manually recorded daily diary symptom and rescue medication use scores and (2) by monthly retrospective report of symptoms embedded within the age-appropriate version of the Asthma Control Test (ACT). Correlations between ACDs and ACT scores were analyzed, and the sensitivity of each method for measuring asthma control and determining the differential response among the three BADGER treatments was evaluated.
RESULTS: Although validated using a 4-week recall period, ACT correlated better with daily diary information from the last 2 weeks of the 4-week recall (r = 0.46) than from the first 2 weeks (r = 0.34). In addition, clinically significant differential treatment responses were detected using ACDs but not ACT scores .
CONCLUSIONS: The results of this study indicate that daily diaries used to determine ACDs can be a more sensitive tool than ACT for assessing differential treatment responses with respect to asthma control.