Validating an alternate version of the chewing function questionnaire

Objectives:Although the chewing function questionnaire proposed by Sato et al.1989 is frequently used to assess perceived chewing ability, psychometric properties of the instrument are not known for major target populations. We report internal consistency, test-retest reliability, and construct validity findings in partially edentulous patients.

Methods:We validated an alternate version of the chewing function questionnaire proposed by Sato et al.(1989) who used 20 items describing various foods taken from 100 items. Patients were asked whether it was easy (“1”) or difficult (“0”) to chew the foods. Item responses were combined resulting in a 0 to 20 summary score where higher scores indicate better chewing ability.

We investigated internal consistency and construct validity in partially edentulous subjects attending the Prosthodontic Clinic at Tokyo Medical and Dental University (N=491, 71% women, age: 62.9 + 11.5 years). For validity assessment, we computed the correlation between the chewing ability and oral health-related quality of life measured by the Japanese 14-item Oral Health Impact Profile (OHIP-14) and the two items characterizing functional limitations in the OHIP-14. In a subset of the patients (N=62), test-retest reliability was assessed asking patients to fill in the questionnaire twice 2 weeks apart.

Results:Internal consistency was “satisfactory” according to guidelines with a Cronbach's alpha of 0.90 (lower limit of 95% CI: 0.89). The chewing ability score was correlated with OHIP-14 scores (-0.46, 95% CI: -0.53 to -0.39) and the sum of the two functional limitations items (-0.42, 95% CI: -0.49 to -0.34) indicating that better chewing scores were associated with less impaired oral health-related quality of life scores. Test-retest was “good” according to guidelines with an intraclass correlation coefficient of 0.69 (95% CI: 0.57 to 0.82).

Conclusion:The alternate version of the chewing ability questionnaire has acceptable reliability and validity in partially edentulous patients.