Cross-cultural adaptation of a psychometric instrument: Two methods compared

Cross cultural adaptations of questionnaires are needed in multilingual res earch, but little is known about the effectiveness of specific translation methods. We compared properties of two French-language adaptations of the S F36 health survey: (a) a rapid translation developed over 3 months in Genev a in 1992 (Geneva version), based on three initial translations, one synthe sis, and two pretests, and (b) a comprehensive adaptation developed by the international Quality of Life Assessment Project between 1991 and 1994 (IQO LA version), which involved back translations, focus groups, development of equidistant response options, item difficulty and quality ratings, and mul tiple pretests. Wordings of 34 of 36 items differed. These two instruments were administered 1 year apart to the same sample of 946 young adults. Ceil ing effects were somewhat lower for the IQOLA than for the Geneva version ( means 30.4% and 35.5%), and missing scores slightly less frequent (IQOLA: m ean 0.5%; Geneva: 1.2%). Floor effects (means 2.7% and 2.4%), proportions o f consistent respondents (93.4% and 94.0%), and internal consistency coeffi cients (IQOLA: 0.78-0.89, Geneva: 0.80-0.92) were similar. Factor analysis supported the existence of two main aspects of health (physical and mental) for both versions. A majority of known-group comparisons were compatible w ith theory, for both versions. In conclusion, the two French-language versi ons of the SF36 had similar psychometric properties, despite extensive diff erences in the development process. This suggests that a moderately resourc e-intensive translation may produce adequate results. More empirical resear ch is needed to understand what translation methods yield the best results. J CLIN EPIDEMIOL 52;11:1037-1046, 1999. (C) 1999 Elsevier Science Inc. All rights reserved.