[Reference guidelines for the 12-Item Short-Form Health Survey version 2 based on the Catalan general population]

Abstract

Background and objective: The SF-12 health survey is the short version of the SF-36. The main interpretation strategy for these health related quality of life (HRQL) questionnaires is the use of population based reference values. This study aims to obtain the population based norms for the Spanish version of SF-12 version 2 (SF-12v2), to evaluate its construct validity and to compare the scores obtained by the standard and the specific method of calculation.

Subjects and methods: We analyzed a subsample of the Catalan Health Interview Survey (n=4,261), representative of the general non-institutionalized population. Median and percentiles were calculated for each of the 8 dimensions and for the component summaries, stratified by sex and age groups. The construct validity was evaluated by comparing known groups, applying ANOVA.

Results: The results for the known groups analysis supported the hypothesis established a priori (P<.001): worse physical health for persons with mobility problems (EQ-5D) (37.8 vs 52), with restriction in activities (41.8 vs 51.2), and with greater number of chronic disorders (from 43.2 to 53.9); and worse mental health with problems of anxiety/depression (EQ-5D) (42.2 vs 51.9). The scores obtained by the 2 different methods of calculation were similar, except for General Health and Vitality.

Conclusions: The SF-12v2 is a valid instrument to measure HQRL in our environment. The obtained norms facilitate the interpretation of SF-12v2 scores in the clinical practice, research and health policy. We recommend the use of the specific method of calculation for national HRQL comparison and the standard one for international comparison.