Weekly self-measurement of FEV1 and PEF and its impact on ACQ (asthma control questionnaire)-scores: 12-week observational study with 76 patients

Abstract

The "Asthma Control Questionnaire" (ACQ) is a very common questionnaire for assessing asthma control. This study compares different ACQ versions in a self-monitoring program over a 12-week period combining them with patients' self-measurements of peak expiratory flow (PEF) and forced expiratory volume in one second (FEV1). The objective was to test the feasibility of FEV1-self-measurements and to compare ACQ versions regarding possible additional information given by lung function. In this prospective multicenter observational study 100 adult asthma patients, recruited at six family practices and two pulmologists' private practices in Germany, completed the ACQ weekly, performing self-measurements of PEF and FEV1. Seventy-six patients were included into final analysis with only 3% missing values. Scores for all ACQ versions improved significantly (all P-values < 0.05) with reductions of 32% for ACQ5, 31% for ACQ6, 22% for ACQ7-FEV1, and 21% for ACQ7-PEF with high Pearson's correlation coefficients of all scores (r between 0.96 and 0.99). ACQ7-FEV1 scores were significantly higher than others. Separated courses of lung function parameters showed nearly no change, but ACQ5 and ACQ6 as scores for symptoms and reliever medication improved constantly. ACQ5 and ACQ6 revealed higher percentages of patients classified as "controlled" than ACQ7-scores. In conclusion, with only a few missing data points, our results suggest feasibility of FEV1-self-measurements. Courses of symptom-related and lung function-related ACQ items differ clearly. Our results support the GINA recommendations to consider symptoms and lung function separately. FEV1-self-measurements for research purposes may be included with the ACQ, but in clinical practice seem to measure a different domain to symptomatic asthma control.

Fig. 1

Means of summary scores of the four versions of the ACQ (black lines) and of the single ACQ-items for FEV1-%predicted and PEF %-predicted (grey lines) from week 1 to week 12, ACQ-scores for single items and summary scores range from 0 to 6. (Analyses are based on available data per week (number of available observations between 69 and 75). Standard errors for the single measurement points range between 0.1 and 0.2)

Fig. 2

Means of the single ACQ items from week 1 to week 12, scores for single ACQ-items range from 0 to 6. Analyses are based on available data per week (number of available observations between 71 and 76). Standard errors for the single measurement points range between 0.1 and 0.2

Fig. 3

Proportion of participants with asthma classified as controlled (≤0.75) according to different ACQ versions, indicated in percent from week 1 to week 12. Analyses are based on available data per week (number of available observations between 69 and 75)