[Measuring psychosocial stress at work in Spanish hospital's personnel. Psychometric properties of the Spanish version of Effort-Reward Imbalance model].

BACKGROUND AND
OBJECTIVE: Two main models are currently used to evaluate the psychosocial factors at work: the Demand-Control (or job strain) model developed by Karasek and the Effort-Reward Imbalance model, developed by Siegrist. A Spanish version of the first model has been validated, yet so far no validated Spanish version of the second model is available. The objective of this study was to explore the psychometric properties of the Spanish version of the Effort-Reward Imbalance model in terms of internal consistency, factorial validity, and discriminate validity. SUBJECTS AND METHODS: A cross-sectional study on a representative sample of 298 workers of the Spanish public hospital San Agustin in Asturias was performed. The Spanish version of Effort-Reward Imbalance Questionnaire (23 items) was obtained by a standard forward/backward translation procedure, and the information was gathered by a self-administered application. Exploratory factor analysis were performed to test the dimensional structure of the theoretical model. Cronbach's alpha coefficient was calculated to estimate the internal consistency reliability. Information on discriminate validity is given for sex, age and education. Differences were calculated with the t-test for two independent samples or ANOVA, respectively.
RESULTS: Internal consistency was satisfactory for the two scales (reward and intrinsic effort) and Cronbach's Alpha coefficients higher than 0.80 were observed. The internal consistency for the scale of extrinsic effort was lower (alpha = 0.63). A three-factor solution was retained for the factor analysis of reward as expected, and these dimensions were interpreted as a) esteem, b) job promotion and salary and c) job instability. A one-factor solution was retained for the factor analysis of intrinsic effort. The factor analysis of the scale of extrinsic effort did not support the expected one-dimension structure. The analysis of discriminate validity displayed significant associations between measures of Effort-Reward Imbalance and the variables of sex, age and education level.
CONCLUSIONS: This study is the first one supporting satisfactory psychometric properties of the Spanish version of the Effort-Reward Imbalance model. However, the factorial validity of the extrinsic effort could be questioned.