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

Abstract

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.

Figure 1.

Study design. *During each period, patients received ICS plus one of three add-on treatments: ICS, long-acting β-agonist (LABA), or leukotriene receptor antagonist (LTRA). ACT = Asthma Control Test; c-ACT = Childhood Asthma Control Test; ICS = inhaled corticosteroid.

Figure 2.

Correlations between percent asthma control days and ACT. See Figure 1 legend for expansion of abbreviation.

Figure 3.

Association between greatest ACD differential response and ACT differential response in all children. Each data point is a difference between two treatment period averages. On the y-axis, the reference lines at −3 and +3 reflect the published clinically minimally important differences for the ACT. All points to the right of the vertical line represent a significant differential response on the basis of criteria used in the original Best Add-on Therapy Giving Effective Responses (BADGER) trial (ie, > 31 annualized ACD, which corresponds to 8.5% ACD). For threshold values of < 31 d, the observed relationships did not change significantly; therefore, the final analyses were based on the 31-d threshold. Correlation = 0.24. ACD = asthma control day. See Figure 1 legend for expansion of other abbreviation.