Twenty-one cross-sectional diagnostic accuracy studies (23,624 patients) were included in the review. Twelve studies assessed the Asthma Control Test, six studies assessed the Asthma Control Questionnaire and three studies assessed both tools. Only three studies were considered to have overall low risk of bias. All studies had low concern regarding applicability.
Prespecified cut-off studies assessing the Asthma Control Test showed good diagnostic accuracy in "controlled" asthma patients (sensitivity 0.77, 95% CI 0.68 to 0.84, specificity 0.84, 95% CI 0.74 to 0.91; nine studies) and "not well-controlled" patients (sensitivity 0.75, 95% CI 0.63 to 0.83, specificity 0.82, 95% CI 0.76 to 0.87; 11 studies) but not for "uncontrolled" asthma patients (sensitivity 0.49, 95% CI 0.42 to 0.56, specificity 0.92, 95% CI 0.86 to 0.96; seven studies). Statistical heterogeneity was reported for pooled estimates.
All three versions of the Asthma Control Questionnaire had higher sensitivity compared to the Asthma Control Test but lower specificity in "controlled" asthma patients (median results were reported as fewer than four studies assessed this outcome). The Asthma Control Questionnaire showed good diagnostic accuracy in "not well-controlled patients" using version 7 (sensitivity 0.74, 95% CI 0.61 to 0.83, specificity 0.81, 95% CI 0.72 to 0.88; five studies) and version 6 (sensitivity 0.65, 95% CI 0.52 to 0.76, specificity 0.90, 95% CI 0.86 to 0.92; four studies) but there was some evidence of statistical heterogeneity. Version 5 of the Asthma Control Questionnaire showed slightly higher specificity compared to the Asthma Control Test but lower sensitivity (three studies) in "not well-controlled" patients (median results were reported as fewer than four studies assessed this outcome).
Sensitivity and specificity values significantly increased for both the Asthma Control Test and Asthma Control Questionnaire when non-prespecified cut-off value studies were assessed and compared to prespecified studies.
Pooled results for likelihood ratios and diagnostic ratios were reported in the review. Results for subgroup analyses and meta-regression were reported in the review. Funnel plots suggested that potentially relevant unpublished data may have been missed.