Psychometric Characteristics of the Croatian and the Serbian Versions of the Oral Health Impact Profile for Edentulous Subjects, with a Pilot Study on the Dimensionality.

Introduction: The aim was to adapt the Croatian and the Serbian versions of the Oral Health Impact Profile for the edentulous population (OHIP-EDENT-CRO and OHIP-EDENT-SRB).

Methods: The translation and cross-cultural adaptation were carried out in accordance with accepted international standards. A total of 95 and 177 removable denture wearers were recruited in Croatia and Serbia respectively. The reliability was evaluated by calculating Cronbach's alpha coefficient and by test-retest (30 participants in each country). The concurrent validity was determined by calculating the Spearman's rank coefficient between the OHIP-EDENT summary scores and one question related to removable denture satisfaction. Construct validity was determined by exploratory factor analysis (EFA). Responsiveness was determined by comparison of the OHIP-EDENT summary scores before and after dental implant placement to support mandibular overdentures (23 patients in Croatia, 21 in Serbia).

Results: Cronbach's alpha coefficient was 0.92 in Croatia and 0.87 in Serbia. The intraclass correlation coefficient was 0.98 in Croatia and 0.94 in Serbia. In Croatia the Spearman's correlation coefficient was -0.71 (p<0.001) and in Serbia -0.74 (p<0.001). Both confirmed concurrent validity. Construct validity was tested by EFA, which extracted four factors in each country, accounting for 66.59% of the variance in Croatia and 59.33% in Serbia. Responsiveness was confirmed in both countries by a significant OHIP-EDENT summary score reduction and a high standardised effect size (3.9 in Croatia, 1.53 in Serbia).

Conclusion: The results prove that both instruments, the OHIP-EDENT-CRO and the OHIP-EDENT-SRB, have very good psychometric properties for assessing OHRQoL in the edentulous population.