[Adaptation of a measure of dysfunction-related illness: the Spanish version of Sickness Impact Profile]

The aim of the research was to adapt the Sickness Impact Profile (SIP) for their use in Spain. The Sickness Impact Profile is a questionnaire that measure the dysfunction related illness in 12 categories. It contain 136 items weighted by the relative importance in each category. In the present article we described the translation and the preliminary weighting process of each item and category.

In the translation we used the back-translation method by means of English-American and Spanish bilinguals. The items with equivalence B or C were discussed with a group of patients until to reach an agreement in the version. The scaling was carried out by 25 judges (health professionals). Following the same methodology as the original version, the judges firstly placed the relative values of each item in each category on an interval scale of 1 (minimal dysfunction) to 11 (maximal dysfunction) points; secondly the items most and least dysfunctional in each category were placed on a 1-15 interval scale (method of equal appearing intervals).

In the translation process we identify 12 items with equivalence B or C. The results showed a high correlation between the values obtained by each judge and the mean values of the judges by item (0.64-0.81). The items were rated with a standard deviation of the mean of 1.91 and a standard deviation of the standard deviation of 0.52. The correlation between Spanish and American values was r = 0.84 (p < 0.001).

Given the low number of non-equivalent items, the high agreement among the judges in the valuation of the items and the high correlations obtained between the Spanish and American weights, we conclude that the cross-cultural process have been satisfactory. The results should be to repeat in a sample of health consumers. The process of adaptation of the Spanish version will not finish until that the validity and reliability are similar to those of the original version.