The development of an ICF-based questionnaire for patients with chronic conditions in primary care.

We developed a self-reported questionnaire for patients in primary care with chronic conditions aged 50 years or older. The questionnaire supports a more person-centered approach by adopting a biopsychosocial focus on functional status instead of a focus on disease. Based on the International Classification of Functioning, Disability and Health (ICF), an ICF Primary Care set for patients with chronic conditions was constructed in three phases. In the first phase, we identified relevant ICF categories for the ICF Primary Care set by using existing ICF sets for chronic health conditions. The ICF Primary Care set was completed by a multidisciplinary expert panel and consisted of 52 ICF categories covering ICF's body functions, activities, participation, environmental factors, and personal factors. In the last phase, we constructed a draft version of the questionnaire by converting the ICF categories from the ICF Primary Care set into questions and corresponding scales. In order to improve the draft version of the questionnaire we conducted cognitive interviews with patients with chronic conditions in an iterative process, focusing on the problems patients experienced in answering the items of the questionnaire. Interview analysis was used for assessing the content and construct validity of the questionnaire. Thirty cognitive interviews with patients were conducted in 5 different interview rounds. In these interviews, we identified 124 problems in the responding process of answering the questionnaire, mostly concerning difficulties with the comprehension of the constructs of the questions. The number of problems reduced from an average of 11 problems per interview in the first round to an average of 2 problems in the last round. The final version of the questionnaire demonstrated high content and construct validity, (i.e. patients are well capable of describing their functional status in terms of ICF) and is applicable in primary care in the Netherlands.