[Validating the Spanish version of the Nursing Activities Score]

Validating workload scores ensures that they are appropriate for the purpose for which they were developed.

To validate the Nursing Activities Score (NAS) Spanish version.

Observational and prospective study. 1,045 patients who were admitted to a medical-surgical unit and a serious burns unit in 2006 were included. The nurse in charge assessed patient workloads by Nine Equivalent of Nursing Manpower use Score and NAS. To assess the internal consistency of the measurements of NAS, item-test correlations, Cronbach's α and Cronbach's α corrected by omitting each of the items were calculated. The intraobserver and interobserver reliability were assessed with the intraclass correlation coefficient by viewing recordings and Kappa (interobserver reliability) was estimated. For the analysis of internal validity, a factorial principal components analysis was performed. Convergent validity was assessed using the Spearman correlation coefficient values obtained from the Nine Equivalent of Nursing Manpower use Score and Spanish-NAS scales.

For internal consistency, 164 questionnaires were analysed and a Cronbach's α of 0.373 was calculated. The intraclass correlation coefficient for intraobserver reliability estimate was 0.837 (95% IC: 0.466-0.950) and 0.662 (95% IC: 0.033-0.882) for interobserver reliability. The estimated kappa was 0.371. For internal validity, exploratory factor analysis showed that the first item explained 58.9% of the variance of the questionnaire. For convergent validity 1006 questionnaires were included and a Spearman correlation coefficient of 0.746 was observed.

The psychometric properties of Spanish-NAS are acceptable.