Validity of self-reported number of teeth in middle-aged Finnish adults: the Northern Finland Birth Cohort Study 1966

Abstract

<div><b>Background</b></div><div><b><br /></b></div><div>We examined the validity of self-reported number of teeth in middle-aged adults by using representative cohort data to compare corresponding self-reported and clinical values.</div><div><br /></div><div><b>Methods</b></div><div><br /></div><div>This validity study is part of the representative 46-year-old follow-up of the Northern Finland Birth Cohort 1966 (NFBC1966) Study. Mailed questionnaires (n=5950) requested information on self-reported number of teeth and background variables (education, tooth brushing and smoking), while clinical oral health examinations (n=1891) assessed the number of teeth (the gold standard'). The main analyses compared the self-reported and clinical values for the number of teeth in 1669 participants. Scatterplot and Bland-Altman plot served for visual analyses, and alternative correlation coefficients (Pearson, Spearman, intraclass) for numerical comparisons separately for men and women, with stratification according to background variables.</div><div><br /></div><div><b>Results</b></div><div><br /></div><div>The clinical assessment revealed that the mean value for the number of teeth was 27.46 (SD=2.38), while the corresponding value based on self-reported information was 27.48 (SD=2.78). According to the Bland-Altman plot, the mean difference between the clinical and self-reported values was -0.02 (95% limits of agreement, LoA: -3.37 to 3.32). The observed ranges of intraclass correlation coefficients (ICC) among men and women were 0.72 to 0.95 and 0.72 to 0.85, respectively, depending on the background variables.</div><div><br /></div><div><b>Conclusions</b></div><div><br /></div><div>Self-reported number of teeth in middle-aged Finnish adults agreed closely with the corresponding clinical measure.</div>