Does the mode of administration of the Oral Health Impact Profile-49 affect the outcome score?

OBJECTIVE: To determine if there are differences in outcome scores if the Oral Health Impact Profile-49 (OHIP-49) is delivered by two different modes of administration (manual-self complete versus telephone interview). METHODS: Patients with chronic periodontitis (n=83, 54% females and 46% males, mean age 49.1+/-9.5 years) completed the OHIP-49 using two modes of administration (manual self-complete and telephone interview) in a randomly assigned order, with a minimum washout period of 2 weeks between modes, both episodes occurring prior to any periodontal treatment being provided. To assess convergent validity, after each mode of administration, the patients were additionally asked a global question about their oral health-related quality of life (OHRQoL). RESULTS: Median OHIP-49 scores recorded by manual self-complete (median 36 [IQR=20-70]) were significantly higher than those recorded by telephone interview (median 27 [IQR=11-61]) (p<0.01). The global question was well correlated to the OHIP domains, but did not reveal any evidence of an order effect such as was seen with OHIP-49 itself (which showed a higher impact on OHRQoL during the first administration in either mode). CONCLUSIONS: The mode of administration (manual-self complete versus telephone interview) did substantially influence the OHIP-49 scores in patients with chronic periodontitis. The OHRQoL differed between the two modes of administration, with significantly higher scores (indicating poorer OHRQoL) when the questionnaire was manually self-completed. CLINICAL SIGNIFICANCE: The mode of administration of quality of life questionnaires such as OHIP-49 could potentially affect the outcome scores derived. This study investigated whether there is a difference in outcome scores if OHIP-49 is delivered via manual self-complete or by telephone interview in patients with chronic periodontitis. We found that there was a significant difference between the two modes: manual self-completion by the patients yielded significantly higher scores than completion by telephone interview. It is therefore important to be consistent in the mode of completion of OHIP-49, as mixing modes could introduce additional error into clinical studies that utilise this instrument.