Setting up a cohort study of functioning: From classification to measurement.

Objective: Cohort studies are an appropriate method for the collection of population-based longitudinal data to track people's health and functioning over time. However, describing and understanding functioning in its complexity with all its determinants is one of the biggest challenges faced by clinicians and researchers.

Design: This paper focuses on the development of a cohort study on functioning, outlining the relevant steps and related methods, and illustrating these with reference to the Swiss Spinal Cord Injury Cohort Study (SwiSCI).

Methods And Results: In setting up a cohort study the initial step is to specify which variables are to be included, i.e. what to assess. The International Classification of Functioning, Disability and Health (ICF) is valuable in this process. The second step is to identify how to assess the specified ICF categories. Existing instruments and assessments can then be linked to the ICF.

Conclusion: The methods outlined here enable the development of a cohort study to be based on a comprehensive perspective of health, operationalized through functioning as conceptualized and classified in the ICF, yet to remain efficient and feasible to administer.