Methods: Subjects were a convenience sample of 42 adult patients (age mean+/-sd: 57.5+/-15.7 years, 57% women) recruited at the Department of Prosthodontics and Materials Science, University of Leipzig. During a time period of three to four weeks where their oral health-related quality of life (OHRQoL) was considered to be stable, the patients were approached three times using a face-to-face interview performed by a dentist, a telephone interview performed by a research assistant, and a self-administered questionnaire. The order of the administration modi was randomized. OHRQoL was measured using the German version of the 49-item Oral Health Impact Profile. OHIP summary score reliability was assessed using Cronbach's alpha. A spearman rank correlation coefficient was calculated correlating OHIP scores with an ordinal measure of self-reported oral health (5 categories from poor to excellent) for validity assessment. Reliability and validity coefficients were compared to previously published values for OHIP scores in N=163 general population subjects (John et al. 2002).
Results: Cronbach's alphas for OHIP scores for the three adminstration modi were 0.97, 0.97, and 0.96 compared with 0.96 in general population subjects. Spearman rank corrrelations for the three adminstration modi were 0.60, 0.60, 0.43 compared with 0.56 from the previous study.
Conclusion: When OHIP was administered by three different modi (personal interview, telephone interview, and self-administered questionnaire) to prosthodontic patients, measures of OHIP scores' internal consistency and validity were similar compared to previous results in general population subjects.