The sum of medical interventions can do more harm than good. Supporting patients' resources instead of combating disease might effectively help reducing "too much medicine". A first step to approach this goal would be to have a classification tool that captures the essential features of a meaningful human life, namely body functions, activities, and participation. The International Classification of Functioning, Disability and Health (ICF) is the perfect framework to distinguish between necessary and unnecessary medical interventions by offering descriptions of outcomes of medical and non-medical interventions. However, though adequate and comprehensive in theory, it is impracticable in a primary care setting. Therefore, a core set of the ICF for the old and very old in primary care is needed. Four preparatory studies according to the international development guideline will be carried out: a systematic literature review to capture the research perspective, a qualitative study to assess the patients' perspective, an experts' survey and an empirical multicenter study to detect the clinical perspective.

The systematic literature review captures the perspective of researchers on functioning of community dwelling people aged 75 years and older. Different literature databases will be searched combining search terms referring to community dwelling elderly and to functioning. Two investigators will independently screen the abstracts and titles for eligibility. In reviewing the full articles, the underlying concepts that are contained in the measures and in the article text will be identified, and then linked to the ICF categories using established linking rules. A frequency analysis will be conducted on the linked categories. The ICF categories that are identified in at least 5% of all publications will be included in the list of candidate categories.

The qualitative study aims to identify which aspects of functioning, environmental and personal factors are most important to community dwelling people aged 75 years and older. Participants will be provided with a camera for one week to take pictures of activities they are no longer able to perform or activities they still perform well. On the basis of these pictures, individual interviews and focus groups will be conducted. Meaningful concepts will be identified and linked to the ICF categories.

The expert survey aims to gather opinions of experts on aspects of functioning and environmental factors that are relevant for community dwelling people aged 75 years and older. Meaningful concepts will be identified and linked to the ICF categories.

The empirical multicenter study aims to identify the most common problems experienced by community-dwelling people aged 75 and older using clinical assessments. A health professional will conduct semi-structured interviews based on the extended ICF checklist. This is a selection of 125 categories that are considered to be most important for clinical practice. This list is extended by other categories thought to be sensitive to functioning in old age.

Systematic review:

Inclusion criteria:

• conducted in the EU, EFTA countries, Australia, New Zealand, USA, Canada
• published in a peer-review journal
• published since 2007
• RCT, controlled clinical trial, cross-sectional study, observational study, qualitative study

Exclusion criteria:

• studies which are solely based on one certain disease
• studies which are solely based on one ethnic group
• studies with hospitalized participants

Qualitative study/empirical multicenter study:

Inclusion criteria:

• community-dwelling people aged 75 years and older

Exclusion criteria:

• people with dementia
• people living in nursing homes
• people in palliative care

Expert survey:

Inclusion criteria

• General practitioners, geriatricians and caregivers with at least two years of professional experience in ambulatory care.

Community-dwelling people aged 75 years and older.