Examination of the cut-off values for a questionnaire used to evaluate asthma control in Japanese asthma patients

Background: The Japan Asthma Control Survey (JACS) questionnaire, developed as a tool for measuring asthma control levels in Japanese asthma patients, was previously tested for its reliability and validity. However, many of the patients enrolled in the original validation study had mild asthma; thus a re-evaluation including severe cases was required to calculate more reliable cut-off values.

Methods: Pooled analysis of data from the original validation study and the subsequent medication guidance study including adult patients with severe asthma was conducted to calculate the JACS questionnaire cut-off values and to assess their sensitivity and specificity for identifying "well-controlled", "not well-controlled", and "poorly controlled" asthma as described in the Asthma Prevention and Management Guideline 2015 (JGL2015). The data were from 353 patients with mild to severe persistent asthma classified according to JGL2015.

Results: The JACS questionnaire cut-off values were 8.0 (sensitivity, 67.9%; specificity, 81.9%) for "well-controlled" and "not well-controlled" and 4.8 (sensitivity, 85.3%; specificity, 53.3%) for "not well-controlled" and "poorly controlled".

Conclusions: JACS cut-off values can be expected to be more useful for evaluating asthma control status in clinical practice and clinical research, thus improving asthma treatment, in Japan. This analysis was the original validation study (UMIN000016589) and the subsequent medication guidance study (UMIN000024353).