Adaptation to European Spanish and psychometric properties of the Patient Activation Measure 13 in patients with chronic diseases.

Background: The 13-item Patient Activation Measure (PAM-13) is an instrument that assesses people's knowledge, skills and confidence for self-management of their health and health care. Scores on the PAM-13 have been shown to predict adherence to health behaviours, health-related outcomes and health care costs.
Objectives: To develop a European Spanish adaptation of the original PAM-13 and to examine its psychometric properties in a sample of chronic patients.
Methods: The PAM-13 was forward-backward translated and then completed by chronic patients attending a primary health care centre. Data were analysed with a Rasch model. We assessed the functioning of the rating scale, its reliability, the item goodness-of-fit, differential item functioning (DIF), local dependence, unidimensionality and correlation analysis.
Results: A total of 208 patients (80%) completed the questionnaire. Data showed a fit to the Rasch model. More than 50% of patients endorsed all the items. Item rank for the Spanish sample was similar to the original, with few differences. We found significant differences (P < 0.05) in PAM-13 measures according to adherence to prescribed medicines and positive correlations with self-efficacy and physical quality of life. Conclusions: The European Spanish PAM-13 is a reliable and valid instrument for assessing activation in patients with chronic disease in Spain. We suggest adding new items to the instrument so as to examine patients with higher activation levels in the future. Further studies are needed to evaluate the usefulness of this new Spanish PAM-13 in different settings and populations, as well as to examine the relationship between PAM-13 scores and other health-related outcomes.