Can the Asthma Control Questionnaire be used to differentiate between patients with controlled and uncontrolled asthma symptoms? A pilot study.

BACKGROUND: A substantial number of adult patients with asthma are inadequately controlled despite the availability of effective asthma treatment. Patients and physicians seem to overestimate the level of asthma control.
OBJECTIVE: The current study explores whether valid differentiation is possible between asthma patients with controlled and uncontrolled asthma symptoms, on the basis of the Asthma Control Questionnaire (ACQ).
METHODS: In this multi-centre, cross-sectional study, patients were classified according to Global Initiative for Asthma criteria into levels of asthma symptom control based on a diary card registration. We defined Step 1 ('well controlled' asthma symptoms), Step 2 ('moderately controlled'), Step 3 ('poorly controlled') and Step 4 ('very poorly controlled'). These control steps were related with the sum score of the ACQ.
RESULTS: From 108 asthma patients complete data were obtained. The Step 1 subgroup comprised 17 patients; Step 2, 12 patients; Step 3, 22 patients; and Step 4, 57 patients. Receiver Operating Characteristic curve analysis showed that the optimal ACQ sum score cut-off value to differentiate between Step 1 and Steps 2, 3 and 4 was three points (sensitivity: 84%, specificity: 76%). For Steps 1 and 2 versus Steps 3 and 4, this was four points (sensitivity: 77%, specificity: 59%). For Steps 1, 2 and 3 versus Step 4, this was six points (sensitivity: 70%, specificity: 74%).
CONCLUSION: Our results show that discrimination between asthma patients with controlled and uncontrolled asthma symptoms, based on the ACQ, is possible with a reasonable margin of test inaccuracy. Thus, the ACQ may be an important tool for health care professionals who aim to optimize the level of asthma control in their patient population.