PRELIMINARY PSYCHOMETRIC ANALYSIS OF THE FRENCH VERSION OF AN INTERNATIONAL QUALITY-OF-LIFE QUESTIONNAIRE - THE MOS SF-36 (VERSION-1.1)

The International Quality Of Life Assessment (IQOLA) Project is a 4 ye ar project initiated in 1991 to translate and adapt the Medical Outcom e Study Short Form 36 item Health Survey (SF-36) in at least 15 countr ies. This paper reports on the preliminary psychometric assessment of the SF-36 in French (version 1.1). The validation data come from two s tudies: a phase IV study of 121 patients with arthritis and a phase Ty study of 159 patients with angina. In both cases, the patients were s urveyed using the SF-36 and a disease specific module. The main object ive of this analysis was to determine how well the scaling assumptions (summated rating or Likert type scaling construction) of the SF-36 we re satisfied. Item convergent validity was supported as items-scale co rrelation range from 0.47 - 0.87. Item discriminant validity was suppo rted as all items were more correlated with their hypothesised scales than with scales measuring other concepts. Our data support the assump tion that the items measuring the same concept had approximately equal variance. Items in a given scale contained about the same proportion of information about the concept being measured as most items of any g iven dimension had approximately the same correlation with that dimens ion. The Cronbach alpha coefficient ranged between 0.79 and 0.95. The correlation between two scales was less than the reliability coefficie nt for those scales, and these correlations adjusted for attenuation w ere less than 1. These preliminary results are encouraging. They indic ate that the items are linearly related to the underlying concept bein g measured. There is good evidence of the existence of a unique and re liable variance which is measured by each scale score and it seems rea sonable to suggest that scales scores are reproducible and interpretab le. All this supports the claim that the scaling properties of this Fr ench version of the SF-36 are respected and that health outcomes may b e reliably assessed using this version.