Cross-cultural equivalence in translations of the oral health impact profile.

The Oral Health Impact Profile (OHIP) has been translated for comparisons across cultural boundaries. This report on a systematic search of literature published between 1994 and 2014 aims to identify an acceptable method of translating psychometric instruments for cross-cultural equivalence, and how they were used to translate the OHIP. An electronic search used the keywords 'cultural adaptation', 'validation', 'Oral Health Impact Profile' and 'OHIP' in MEDLINE and EMBASE databases supplemented by reference links and grey literature. It included papers on methods of cross-cultural translation and translations of the OHIP for dentulous adults and adolescents, and excluded papers without translational details or limited to specific disorders. The search identified eight steps to cross-cultural equivalence, and 36 (plus three supplemental) translations of the OHIP. The steps involve assessment of (i) forward/backward translation by committee, (ii) constructs, (iii) item interpretations, (iv) interval scales, (v) convergent validity, (vi) discriminant validity, (vii) responsiveness to clinical change and (viii) pilot tests. Most (>60%) of the translations involved forward/backward translation by committee, item interpretations, interval scales, convergence, discrimination and pilot tests, but fewer assessed the underlying theory (47%) or responsiveness to clinical change (28%). An acceptable method for translating quality of life-related psychometric instruments for cross-cultural equivalence has eight procedural steps, and most of the 36 OHIP translations involved at least five of the steps. Only translations to Saudi Arabian Arabic, Chinese Mandarin, German and Japanese used all eight steps to claim cultural equivalence with the original OHIP.