Psychometric properties of the Croatian version of OIDP index

Aim of the study was to translate and test the psychometric properties of the OIDP  (Oral Impacts on Daily Performances) index in order to make it available for usage in Croatian population.

Method:

OIDP questionnaire was translated from English to Croatian language by four postgraduate dental students. Backward translation was also performed. Preliminary study was performed on 61 subjects. Questionnaire intelligibility was tested on 32 subjects. Face and content validity were additionally discussed by two postgraduate dental students and three dental school professors. Intelligibility, construct validity and internal reliability of the questionnaire were tested on 400 subjects from Zagreb and surrounding area. Additionally, 200 validity questionnaires were used. Test-retest validity was determined by means of repeated direct interview with 32 subjects with one week to one month pause between interviews. MS Excel and SPSS for windows version 16 were used for data processing

Result:

From the total number of subjects there were 394 (98,5%) questionnaires. Intelligibility of the questionnaire was very good/excellent in the majority of cases, with female subjects showing better understanding of questions. Standardized Chronbach's alpha as the internal reliability measure was 0,817 with positive inter-item correlations. Number of filled validity questionnaires was 197 (98,5%). There was a positive correlation between OIDP questionnaire and validity questionnaire results (Pearson's correlation, p<0,05). Test-retest validity showed no difference between the first and repeated measurement for both, the total result of the questionnaire as well as for the results of each individual item (Wilcoxon signed rank test, p>0,05).

Conclusion:

Results demonstrated appropriate psychometric properties of the OIDP questionnaire. Content and criterion validity, reliability, test-retest consistency and intelligibility parameters were within defined standard values. It can be concluded that Croatian version of OIDP questionnaire can be used as a tool in further oral health quality of life related research.