Validity and reliability of the Spanish version of the psychological general well-being index

The Psychological General Well-Being Index (PGWBI) was adapted for use in Spain. The American version was translated and back-translated independently by three bilinguals and the comprehensibility of a consensuated version was tested in a pilot study. The construct validity and internal consistency of the questionnaire were tested in 104 patients (52 high blood pressure patients attending a primary health care centre and 52 end-stage renal disease patients undergoing hemodialysis). Concurrently to the PGWBI, patients were administered the General Health Questionnaire (GHQ-12) and three psychosocial categories of the Sickness Impact Profile (SIP-PD). Patients in the dialysis group were administered the PGWBI on two occasions, two weeks apart. The PGWBI was moderately to highly correlated with the GHQ-12 (r=-0.71) and with the SIP-PD (r=-0.69). Overall internal consistency as measured by Cronbach's alpha coefficient was 0.94. By dimensions, PGWBI alpha coefficients ranged from 0.56 (Self-control) to 0.88 (Anxiety). No differences were found in mean PGWBI scores between the two groups of patients studied. Two-week test-retest intraclass correlation coefficient was 0.76. The similarity of the operating characteristics supports the contention that the Spanish and American versions of the PGWBI are conceptually equivalent. More research is needed on the reliability and responsiveness of the different dimensions of the questionnaire. Our results suggest that only global scores should be used when making individual comparisons.