gms | German Medical Science

Background: The number of patients suffering from chronic disease is steadily increasing worldwide. In Austria, it is estimated that 36% of the population suffer from a chronic disease. With a chronic disease comes greater responsibility, thus it is important that patients can cope with their illness. We would like to study patient activation and health behavior in patients with chronic diseases. Various questionnaires can be employed in such settings. For instance, the questionnaire PAM-13 has been proposed for patient activation. It consists of 13 items measuring skills, knowledge and confidence of a patient in coping with his chronic disease. It has mainly been used in the English-speaking countries so far.

The main objective of our study is to gain insight how the German version of the PAM-13 can be used in a clinical setting in patients with a chronic disease. The secondary objective is to improve the understanding of the influence of different biological, psychological and social factors on the patients' health behavior.

Methods: The study will focus on patients with macular edema. This illness often occurs in the progress of diabetes and the course of the disease can be modified by patient's behavior. We will conduct a questionnaire-based prospective cross-sectional study. Six questionnaires are used, including measures for social support, quality of life and self-efficacy. The ad-hoc sample investigated will be composed of outpatients with macular edema from the Department of Ophthalmology of Graz, in Austria. The aim is to include 700 patients. After receiving informed consent, each patient included is asked to complete the questionnaires once. This takes approximately half an hour. In general, the study is set up to run for one year having started early March 2020.

For the main objective, the PAM-13 will be analyzed by item response theory (IRT). Thereby construct validity can be confirmed and item parameters can be compared with results from other languages since these parameters are independent of the sample investigated. For that purpose, there are several models. The Rasch Rating Scale Model will be used to investigate item and person statistics, and one-dimensionality of the scale. The Partial Credit Model will be applied, an extension of the original Rasch model for ordinal data. For both models, assumptions like local stochastic independence and fits will be evaluated. Differential item functioning (DIF) will be assessed by estimating item parameters for groups of participants. DIF will be investigated from the model e.g. by using Likelihood Ratio Test and graphical analysis.

A structural equation model will investigate the secondary objective, the relationship between patient activation and factors of the three facets of the biopsychosocial model for health behavior. Scores of questionnaires, medical and demographic data, will build each facet.

Besides these methodological aspects, we will describe patient activation by the PAM-13 from a clinical point of view and deduce the needs of the patients in order to best handle their disease.

The study design, implementation of the study in the clinical setting and first results will be presented.

The authors declare that they have no competing interests.

The authors declare that a positive ethics committee vote has been obtained.