Abstract
Background: In questionnaire surveys, questions about self-reported number of teeth (SRNT) are often used as an indicator to measure oral health status. We investigated the validity of SRNT among older Japanese people.
Methods: In total, 4984 75- and 80-year-old patients who underwent dental examinations were enrolled. A self-administered questionnaire that asked about the number of teeth was used in the analysis. The percentage agreement and kappa value were calculated for the agreement between SRNT and observed numbers of teeth. To identify factors that affect the reliability of SRNT, a logistic regression analysis was performed using correctness of SRNT as the dependent variable.
Results: Among the 3950 participants who responded as to whether they had ≥ 20 teeth, the degree of agreement was 92.9% (kappa value 0.856, p < 0.001) in an objective evaluation. Of the 2621 participants who reported their numbers of teeth, the SRNT and observed number of teeth matched in 57.5% (kappa value 0.559; p < 0.001). Observed number of teeth and annual dental checkup had a significant effect on the accuracy of SRNT. When analyzing the relationship between the number of teeth and smoking status, the estimated statistical value showing the effect of smoking on the number of teeth was lower in SRNT compared to that of the observed number of teeth.
Conclusion: Although SRNT values did not perfectly match the observed numbers of teeth, the results of this study imply that the SRNT of older people is reliable and useful in epidemiological studies.