Oral Impacts on Daily Performance in Norwegian adults: validity, reliability and prevalence estimates.

The Oral Impacts on Daily Performance (OIDP) instrument was translated into Norwegian and reviewed for cultural and conceptual equivalence by a group of bilingual academics. A sample of employees from the University of Bergen completed the Norwegian OIDP frequency questionnaire twice. A total of 173 and 108 subjects participated in the first and the second administration, respectively, of this questionnaire. A two-stage proportionate random sample, comprising 2,000 residents (age-range 16-79 yr), was drawn from the national population register by the Central Bureau of Statistics. Information became available for 1,309 persons who completed telephone interviews. The Norwegian OIDP preserved the overall concept of the English version. Test-retest reliability, in terms of Cohen's kappa, was 0.65, and Cronbach's alpha was high (> or = 0.80). In both samples, variations in the OIDP scores were apparent in relation to self-reported oral health and number of remaining teeth, supporting construct and criterion validity of the inventory. Only three of the OIDP interviews were discarded, which supports face validity. A total of 18.3% confirmed that they had at least one oral impact. Age-specific rates were 17.5%, 19.0%, 17.9% and 18.4% among 16-24, 24-44, 45-66 and 67-79-yr-old participants. The satisfactory psychometric properties provide evidence for the cross-cultural use of the OIDP. The presence of a distinct floor effect indicates poor sensitivity of the OIDP to detect improvements of oral health-related quality of life at a population level. Prevalence estimates were low, suggesting that the current oral health status has little impact on the daily performance of the Norwegian adult population.