Development and validation of a new short form of the self-management ability questionnaire for patients with chronic periodontitis.

OBJECTIVES: To establish and validate a short form of the self-management ability questionnaire (SMAQ) for chronic periodontitis patients. METHODS: A total of 480 chronic periodontitis patients were recruited and divided randomly in into two groups: development group and validation group. The item reduction process of the SMAQ was based on item response theory (IRT) and classical test theory (CTT). The resulting short form of the SMAQ was then validated using exploratory factor analysis (EFA), confirmatory factor analysis (CFA), convergent validity, internal consistency and test-retest reliability. RESULTS: The item reduction process produced a 12-item short-form SMAQ (SMAQ-12). EFA results on the twelve items extracted three factors consistent with the original SMAQ and CFA results demonstrated acceptable goodness-of-fit indices of this three-factor structure. Moreover, the SMAQ-12 scores had high correlations with the original measure (r(s) >/=0.904), good internal consistency and test-retest reliability. CONCLUSIONS: The SMAQ-12 is an easy-to-use, reliable and valid measure for assessing self-management ability in patients with chronic periodontitis.