Item re-scaling of an Italian version of the Sickness Impact Profile: Effect of age and profession of the observers

An Italian version of the Sickness Impact Profile (SIP) obtained by professional and nonprofessional translators was checked for cross-cultural equivalence using a back-translation method followed by two scaling studies. The first scaling study involved 30 health professionals who ranked the items within each category for severity of dysfunction. By comparing Italian and US average ranks, 14 highly discordant items were identified. A revised translation was evaluated in a new study involving 120 observers stratified by age (< 65 versus > or = 65 years) and profession (health versus non health professionals) into 4 groups of the same size. The Italian and American item rank orders were almost equivalent, independently of the age and profession of the observers (93% of the ranks showing differences < 2), suggesting that this Italian version of SIP is cross-culturally unbiased. However, older age was associated with higher variability in the rank orders, and some caution is required for use in the geriatric population.