The Italian SF-36 Health Survey

Abstract

This article reports on the development and validation of the Italian SF-36 Health Survey using data from seven studies in which an Italian version of the SF-36 was administered to more than 7000 subjects between 1991 and 1995. Empirical findings from a wide array of studies and diseases indicate that the performance of the questionnaire improved as the Italian translation was revised and that it met the standards suggested by the literature in terms of feasibility, psychometric tests, and interpretability. This generally satisfactory picture strengthens the idea that the Italian SF-36 is as valid and reliable as the original instrument and applicable and valid across age, gender, and disease. Empirical evidence from a cross-sectional survey carried out to norm the final version in a representative sample of 2031 individuals confirms the questionnaire’s characteristics in terms of hypothesized constructs and psychometric behavior and gives a better picture of its external validity (i.e., robustness and generalizability) when administered in settings that are very close to real world.

Introduction

Interest in measuring the aspects of health most closely related to quality of life, usually referred to as health-related quality of life (HR-QOL), has increased in recent years in Italy as in other countries. Advances have been made in methods for describing patients’ subjective health status using standardized measures, and several valid and reliable patient-based measures are available either as generic or disease and treatment targeted questionnaires. However, most of these are in English and are intended for use in English-speaking settings 1, 2, 3.

Very few brand new country-specific instruments have been developed in Italy to measure HR-QOL, and few English instruments that met the investigators’ need have been translated 4, 5. With few but relevant exceptions that were actually translated or developed as part of multilanguage and multinational projects 6, 7, 8, most of such efforts were produced by isolated groups of researchers who seldom published their findings in peer-reviewed journals.

Among the so-called generic measures, the MOS 36-Item Short Form Health Survey (SF-36) is known for its comprehensiveness, brevity, and high standards of reliability and validity 9, 10, 11, 12. It was first translated by independent Italian teams in 1990. With the launch of the International Quality of Life Assessment (IQOLA) project 13, 14, 15, 16 in 1991, the description of the use of the SF-36 in Italy can be spilt up into three parts. The first part regards the pre-IQOLA phase (in which independent translations were used in selected series of studies), the second an intermediate-IQOLA phase (in which an effort was made to trace all potential users and to centralize and harmonize the use of the SF-36 in Italy), and the third and final phase (in which a standardized and accredited Italian SF-36 version was tested in a large representative sample of the Italian general population) (see Figure 1 for a synopsis).

This is the first comprehensive English language report on the development of the Italian SF-36, and it traces the improvement in the psychometric properties of the form as the translation evolved. It also reports on findings from seven studies in which an Italian version of the SF-36 was administered to more than 7000 subjects during 1991 to 1995.