Functioning is recognized as an important study outcome in rheumatoid arthritis (RA). The number of clinical studies addressing functioning as a study endpoint in patients with RA has steadily increased during the past decade [1
]. These investigations have predominantly been guided by the medical perspective, from which the measurement of functioning and health is required to evaluate the patient-relevant outcomes of an intervention and from which functioning and health are seen primarily as a consequence of the disease [2
]. Many of these investigations include patient-oriented instruments, for example, patient and proxy self-reports on health status, quality of life, and health preferences. In rheumatology, the Health Assessment Questionnaire Disability Index (HAQ [3
]) and the Arthritis Impact Measurement Scales (AIMS2 [4
]), which can be considered a generic instrument specific for RA, are widely used.
These instruments have also been developed according to the medical perspective and in line with the current concept in outcomes and quality-of-life research of condition-specific measures [5
], that is, they are based on the assumption that different conditions are associated with salient patient problems in functioning. The individual influence of the environment and personal factors is, however, rarely taken into account [6
]. In addition, widely used RA-specific health-status measures, like the Health Assessment Questionnaire Disability Index, mainly address activities far more than participation [8
]. However, patients' experiences of functioning are determined by their interaction with the environment and their own personal characteristics and not only by the health condition [9
]. RA is also very much associated with the inability to continue working, ultimately leading to the experience of restriction in participation [13
]. Thus, a very comprehensive approach is required when addressing RA.
The bio-psycho-social model of Functioning, Disability and Health of the World Health Organization (WHO) [17
] establishes the basis for a more comprehensive description of the experience of patients suffering from determined disease. Based on this model, functioning, with its components 'Body Functions', 'Body Structures' and 'Activities and Participation', is seen in relation to the health condition under consideration, as well as 'Personal Factors' and 'Environmental Factors' (Figure ) [17
]. Functioning denotes the positive aspects, and disability the negative aspects of the interaction between an individual with a health condition and the contextual factors (Environmental Factors and Personal Factors) of that individual.
The bio-psycho-social model of functioning, disability and health.
This bio-psycho-social view guided the development of the International Classification of Functioning, Disability and Health (ICF), which was approved by the World Health Assembly (WHA) in May 2001. As the ICF has been developed in a worldwide, comprehensive consensus process over the past few years and was endorsed by the WHA as a member of the WHO Family of International Classifications, it is likely to become the generally accepted framework to describe functioning and health. The ICF is intended for use in multiple sectors that, besides health, include education, insurance, labour, health and disability policy, statistics, and so on. In the clinical context, it is intended for use in needs assessment, matching interventions to specific health states, rehabilitation and outcome evaluation. With the ICF, not only an etiologically neutral framework, but a globally agreed-on language and a classification is available to describe functioning on both the individual and population levels and from both the patient perspective and that of the health professionals. The ICF contains more than 1,400 so-called ICF categories, each allotted to the named components in the bio-psycho-social model with the exception of the component Personal Factors, which has not yet been classified. Each ICF category is denoted by a code composed by a letter that refers to the components of the classification (b, Body Functions; s, Body Structures; d, Activities and Participation; e, Environmental Factors) and is followed by a numeric code starting with the chapter number (one digit), followed by the 2nd level (two digits) and the 3rd and 4th levels (one digit each) (Figure ).
All member states of the WHO are now called upon to implement the ICF in multiple sectors that, besides health, include education, insurance, labour, health-and-disability policy, statistics, and so on. However, the ICF has to be tailored to suit these specific applications [18
]. In the clinical context, the main challenge is the length of the classification with its over 1,400 categories. Mainly to address the issue of feasibility regarding the number of categories, ICF Core Sets have been developed in a formal decision making and consensus-based process integrating evidence gathered from preliminary studies for a number of the most burdensome, chronic health conditions, including RA [19
]. The preliminary studies included a Delphi exercise [20
], a systematic review [21
] on outcomes used in randomized clinical trials, which represents the view of researchers performing studies, and an empirical data collection, using the ICF checklist [22
]. Based on these studies, relevant ICF categories were identified. The lists of these identified categories represent the starting point of the decision-making and consensus process that took place at the consensus conference. The ICF Core Sets for patients with a determined health condition represent a selection of ICF categories out of the whole classification that can serve as minimal standards for the reporting of functioning and health for clinical studies and clinical encounters (Brief ICF Core Set) or as standards for multiprofessional, comprehensive assessment (Comprehensive ICF Core Set) under consideration of influential Environmental Factors. Since the ICF Core Sets address aspects within all the components of the ICF (Body Functions, Body Structures, Activities and Participation, Environmental Factors) they present a broad, condition-specific perspective that may reflect the whole health experience of patients. The current version of the Comprehensive ICF Core Set for RA includes 76 categories at the 2nd, 8 categories at the 3rd, and 12 categories at the 4th level of the classification. Regarding the 2nd level of the classification, 15 categories pertain to the component Body Functions, 8 categories to the component Body Structures, 32 categories to the component Activities and Participation and 21 categories to the component Environmental Factors [23
]. The Comprehensive ICF Core Set for RA describes the typical spectrum of problems in functioning among patients with RA encountered in comprehensive assessments or in clinical studies. Additionally, it provides an ideal basis from which to define theoretically sound models of functioning and disability in patients with RA.
The Comprehensive ICF Core Set for RA is now undergoing worldwide testing and validation using a number of approaches, including an international multicenter validation study and validation from the perspective of health professionals. One key aspect is the validation from the patient perspective. While the patient perspective has been implicitly included in the development of ICF Core Sets [22
], the patients now will be explicitly involved in the process of the development and validation of ICF Core Sets. As standards of functioning and health in research and clinical practice, the ICF Core Sets have to show that they address the perspective of those who experience the disease.
Qualitative methodology provides the possibility to explore the perspective of those who experience a health problem, that is, the so-called patient perspective [24
]. Qualitative methods are now widely used and increasingly accepted in health research and health-related sciences [26
]. One of the most broadly used techniques in qualitative research is the focus group methodology [29
]. Focus groups are "carefully planned series of discussions designed to obtain perceptions on a defined area of interest in a permissive, non-threatening environment" [32
]. They are especially useful for studies that involve complex issues that entail many levels of feeling and experience [33
]. "The basic goal in conducting focus groups is to hear from the participants about the topics of interest to the researcher" [34
]. The idea behind this methodology is that group processes can help people to explore and clarify their views [35
]. The non-directive nature of focus groups affords participants an opportunity to comment, explain, disagree and share experiences and attitudes [36
The objective of the present study was twofold: first, to come forward with a proposal for the most appropriate focus group approach to validate Comprehensive ICF Core Sets from the patient perspective; and second, to add evidence to the validation of the Comprehensive ICF Core Set for RA from the perspective of patients with RA based on a group of German patients. The specific aims were to explore the aspects of functioning and health important to patients with RA using two different focus group approaches and to examine to what extent these aspects are represented by the current version of the Comprehensive ICF Core Set for RA.