Validation and optimization of the French Generic Adherence for Chronic Diseases Profile (GACID-P) using classical...

Area of Science:

• Psychometrics
• Health Psychology
• Clinical Research

Background:

• The Generic Adherence for Chronic Diseases Profile (GACID-P) is a French scale designed to assess patient adherence in chronic diseases.
• It is applicable across diverse medical fields including cardiology, rheumatology, diabetes, cancer, and infectiology.

Purpose of the Study:

• To investigate the measurement invariance of the GACID-P using item response modeling.
• To optimize the GACID-P based on item response model and qualitative content analyses.
• To validate the psychometric properties of the optimized instrument.

Main Methods:

• A sample of 397 patients from French hospitals and private practices participated.
• Measurement invariance was assessed using item response theory (IRT) and classical test theory.
• Factor analyses and content analyses were employed for scale optimization.

Main Results:

• The study identified four dimensions of adherence: "Forgetting to take medication," "Intention to comply with treatment," "Limitation of risk-related consumer habits," and "Healthy lifestyle."
• Optimization reduced the scale to 25 items, with satisfactory psychometric properties and calibration.
• Four adherence profile scores were derived, utilizing sum scores and IRT-weighted scores.

Conclusions:

• The optimized GACID-P demonstrates validity through theoretical approach and content analysis.
• The instrument provides four distinct adherence profile scores.
• The validated GACID-P is suitable for research on adherence in a broad range of chronic conditions.