Introduction: Asthma Control Questionnaire (ACQ) is a validated tool to measure asthma control. Cut-off points that best discriminate "well-controlled" or "not well-controlled" asthma have been suggested from the analysis of a large randomized clinical trial but they may not be adequate for daily clinical practice.
Aims: To establish cut-off points of the ACQ that best discriminate the level of control according to Global Initiative for Asthma (GINA) 2006 guidelines in patients with asthma managed at Allergology and Pulmonology Departments as well as Primary Care Centers in Spain.
Patients and methods: An epidemiological descriptive study, with prospective data collection. Asthma control following GINA-2006 classification and 7-item ACQ was assessed. The study population was split in two parts: 2/3 for finding the cut-off points (development population) and 1/3 for validating the results (validation population).
Results: A total of 1,363 stable asthmatic patients were included (mean age 38 ± 14 years, 60.3% women; 69.1% non-smokers). Patient classification according to GINA-defined asthma control was: controlled 13.6%, partially controlled 34.2%, and uncontrolled 52.3%. The ACQ cut-off points that better agreed with GINA-defined asthma control categories were calculated using receiver operating curves (ROC). The analysis showed that ACQ < 0.5 was the optimal cut-off point for "controlled asthma" (sensitivity 74.1%, specificity 77.5%) and 1.00 for "uncontrolled asthma" (sensitivity 73%, specificity 88.2%). Kappa index between GINA categories and ACQ was 0.62 (p < 0.001).
Conclusion: The ACQ cut-off points associated with GINA-defined asthma control in a real-life setting were <0.5 for controlled asthma and ≥1 for uncontrolled asthma.