Concepts important to patients with psoriatic arthritis are not adequately covered by standard measures of functioning

Authors


Abstract

Objective

To explore whether the concepts important to patients with psoriatic arthritis (PsA) are covered by self-report instruments assessing functioning.

Methods

We conducted a qualitative focus group study with PsA patients about their problems in daily functioning. Focus groups were tape recorded and transcribed verbatim. The transcribed texts were divided into meaning units, and concepts contained in these meaning units were extracted. Self-report instruments assessing functioning in PsA were identified in a structured literature search. Using the International Classification of Functioning, Disability and Health (ICF) as a common frame of reference, we determined whether each concept identified in the focus groups was covered by each of the instruments.

Results

Thirty-one patients participated in 6 focus groups. The following 9 instruments were included in the present analysis: Arthritis Impact Measurement Scale Short Form; Bath Ankylosing Spondylitis Disease Activity Index; Disabilities of the Arm, Shoulder, and Hand Questionnaire; Dermatology Quality of Life Index; Dougados Functional Index; Health Assessment Questionnaire (HAQ); HAQ-S (HAQ adapted for spondylarthropathies); PsA-specific Quality of Life Instrument; and Short Form 36 Health Survey. Of the 54 concepts identified in 590 meaning units in the transcribed data, 19 concepts (35%) were not covered by any of the instruments. Of these, 11 concepts that were linked to the ICF component environmental factors were not covered by any of the instruments, whereas all concepts linked to the ICF component activities and participation were covered by at least 1 of the instruments (but no single instrument covered all concepts).

Conclusion

The impact of environmental factors, attitudes towards individuals with health problems, and loss of leisure time may represent important aspects addressing participation that are currently not covered in the instruments assessing functioning in PsA.

INTRODUCTION

Psoriatic arthritis (PsA) is an inflammatory and frequently destructive arthritis that is associated with psoriasis and may be a chronic disabling disease (1). Concerning activity limitations and participation restrictions, patients with PsA report a reduced ability to fulfill personal roles and requirements in paid work and a loss of motivation to take part in social activities (2). Because of the heterogeneity of PsA, different outcomes and corresponding instruments have been used to evaluate the health status of patients with this disease (3).

Depending on the scale of measurement, instruments should fulfill certain quality criteria such as content and face validity, reliability, objectivity, and sensitivity to change (4). The Outcome Measures in Rheumatology Clinical Trials (OMERACT) group expresses this as truth (validity), discrimination (reliability and sensitivity to change), and feasibility (5). Content validity is an important quality criterion if an instrument is selected as an outcome measure. While Rasch analyses and other item-response approaches focus on the relative difficulty of items related to the scoring ability of the subject and the discriminative capacity of the items, content validity or face validity is essential to ensure that an instrument measures all relevant aspects of an outcome (6, 7). Researchers and clinicians therefore need to know whether or not an instrument covers the relevant study outcomes or end points. When considering content validity and relevance of outcomes, it is extremely important to include the patient perspective because personal values for outcomes vary between and among patients and professionals (8–12). Qualitative methodology (11, 13–18) provides the possibility to explore the perspective of those who experience the disease (the patient perspective) (8–12) and to include this perspective in the assessment of the disease (19, 20).

Instruments that have been used to assess functioning in patients with PsA were mainly borrowed from other rheumatic diseases, with few disease-specific instruments for PsA currently available (3, 21). Examples of instruments borrowed from other rheumatic diseases are the Health Assessment Questionnaire (HAQ; borrowed from rheumatoid arthritis [RA]) (22) and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI; borrowed from ankylosing spondylitis) (23). The HAQ (24), Arthritis Impact Measurement Scales (AIMS2) (25), generic Short Form 36 health status questionnaire (SF-36) (26, 27), and Disabilities of the Arm, Shoulder, and Hand Questionnaire (DASH) (28) have been validated in patients with PsA. The PsA-specific Quality of Life Instrument (PsAQoL) (2) has been developed out of the dilemma that some aspects of other instruments, such as some items in the HAQ, have not been found to be related to PsA (29). The Dermatology Quality of Life Index (DLQI) has been developed in patients with dermatologic symptoms including psoriasis (30). There are currently scarce data allowing judgment of which of these instruments best reflect outcomes that are important to the patient's perspective and specifically cover participation in daily life situations (31). Participation is a key term in the International Classification of Functioning, Disability and Health (ICF) model, which offers a comprehensive understanding of functioning. In the ICF, functioning is described as the complex interplay of the health components body functions, body structures, activities and participation, and contextual factors, such as environmental and personal factors (Figure 1). Activity is defined in the ICF as the execution of a task or action by an individual, whereas participation is the person's involvement in a daily life situation (32). Participation may therefore be considered especially important from the perspective of patients because it refers to whether restrictions are experienced in daily life situations.

Figure 1.

The International Classification of Functioning, Disability and Health (ICF) model. The model shows the relationship between the ICF components body functions (categories with the letter b) and body structures (categories with the letter s), activities and participation (categories with the letter d), and the contextual factors environmental factors (categories with the letter e) and personal factors. Each component consists of chapters that then consist of categories. Within the component activities and participation, chapter 4 (mobility) includes the categories d440 fine hand use (second level) and d4400 grasping (third level) among many others.

The purpose of this study was to explore whether the concepts important to patients with PsA are covered by the instruments assessing functioning in PsA. The specific goals were 1) to explore the perspective of patients with PsA, 2) to determine which concepts important to patients are covered by the existing instruments assessing functioning, 3) to identify issues important to patients that are currently not assessed using the existing instruments, and 4) to make recommendations for the further development of existing instruments and development of new instruments integrating the patient perspective.

PATIENTS AND METHODS

We conducted a qualitative study based on focus groups of patients with PsA.

Participants.

To be eligible to participate in the study, patients had to be diagnosed with PsA according to the criteria described by McGonagle et al (33). Patients from the Rheumatology Outpatient Clinic of the Vienna Medical University who were eligible were asked whether they would like to participate in the study and were then fully informed about the study procedures. Patients who were willing to participate had to give written and oral informed consent according to the Declaration of Helsinki 1996. The study was approved by the ethical committee of the Vienna Medical University.

Sample size.

The number of focus groups was determined by saturation, which refers to the point at which an investigator has obtained sufficient information from the field (4). Saturation was defined in our study as the point during data gathering when 2 consecutive focus groups revealed no additional concepts that were not obtained before (11). A small sample size with a diverse range of participants was used to obtain the required level of rich and meaningful data (34). Sampling of patients followed the maximum variation strategy (4, 13) based on the following criteria: disease duration, age group, and professional and educational status.

Interviews.

All focus groups were chaired by the same moderator (TAS) together with 1 or 2 assistants responsible for the observation of the group and the recording of data. Each focus group meeting was tape recorded and transcribed verbatim. A short introduction of the purpose of the study was given in lay terms to all patients at the beginning of each focus group. Patients were asked 5 open-ended questions that were formulated around functioning in daily life based on the ICF model (Figure 1): which PsA-related problems of their body functions they were experiencing, which body structures were involved, which limitations of activities and restrictions in participation were significant to them, which environmental factors were barriers or facilitators for them, and which personal factors were barriers or facilitators for them.

Qualitative data analysis.

Qualitative data analysis followed the method of meaning condensation (13). In the first step, the transcribed interviews were read through by the first author to gain an overview of the collected data. In the second step, the data were divided into meaning units. A meaning unit was defined as a specific unit of text, either a few words or a few sentences with a common theme (35). In the third step, the subconcepts contained in the meaning units were identified. A meaning unit could contain more than 1 subconcept. An example is the meaning unit “Due to my terrible appearance, I abandoned going out to the opera in the evening,” in which we identified the subconcepts “body appearance” and “going out in the evening.” In the fourth step, subconcepts were organized and grouped together according to their meaning to yield more comprehensive concepts. A concept was defined as a separate meaningful entity distinct from other concepts, while several subconcepts shared the attributes of the concept and were therefore subordinate to this concept (13). In the example described above, the subconcept “going out in the evening” was subordinated to the concept “leisure activities.”

Instruments.

The existing and currently used self-report instruments assessing functioning in patients with PsA were identified in a structured literature search that was conducted in the winter of 2005/2006. We used self-report instruments for the present analysis because we focused on the perspective of patients in this study. The following databases were searched using the keywords psoriatic arthritis, instrument, measure, assessment, questionnaire, and outcome measure: CINAHL R (database, 1982–1998 and 1999–2006), PsychINFO (1988–2006), Embase (1988–2006), and Medline (1967–2006). Eligibility of the instruments was checked in 3 steps. Descriptive, evaluative, and psychometric studies were selected. Case reports, economic evaluations, primary prevention studies, and reviews were excluded. Studies and articles that report the use of instruments assessing functioning in PsA were selected. All self-report instruments that were used were documented. Finally, the following criteria for inclusion of the instruments in the analysis were applied: self-report instruments that 1) assessed functioning, 2) were specifically developed for PsA or validated in patients with PsA, 3) were published in a peer-reviewed journal, 4) existed in an English version, and 5) were feasible in a clinical setting.

Procedure to check if a concept was covered by an instrument.

Each concept obtained from the patient focus groups was examined to determine if it was covered by the instruments. To perform this step, we used the ICF as a frame of reference. We linked each concept obtained in the focus groups to the appropriate ICF category according to published linking rules (36, 37) that have been used in qualitative studies (11, 12). According to these linking rules, each concept is linked to the most precise ICF category. If a concept was not contained in the ICF classification, it was assigned as not covered (36), such as the concept “loss of leisure time” in our study.

To determine whether a concept was covered by any of the instruments, we obtained the ICF categories contained in the instruments from previous studies (38–40) and matched them to the linked categories from the focus groups. Thus, we identified the concepts that were covered and not covered in the questionnaires. An example is the concept “fine motor skills of the hand” from the focus groups, which was linked to the ICF category d440 Fine hand use. Items from the AIMS2 Short Form (AIMS2-SF), HAQ, and HAQ-S have been linked to the ICF category d440 Fine hand use (40). Therefore, we considered the concept “fine motor skills of the hand” from the focus groups to be covered by the AIMS2-SF, HAQ, and HAQ-S.

To ensure the validity of the qualitative analysis and the linking to the ICF performed by the first author, the following procedures were performed. First, the identification of the subconcepts and concepts in the complete transcribed text of the focus groups was examined by a second health professional (MM). In case of disagreement, both investigators' opinions were discussed and additional subconcepts were included. Second, all concepts were independently linked to the ICF by another health professional trained in linking concepts to the ICF (MC). The degree of agreement between the 2 investigators in linking concepts to the ICF was calculated by means of the kappa statistic (41). Kappa values generally range from 0 to 1, where 1 indicates perfect agreement and 0 indicates no additional agreement beyond what is expected by chance alone. Kappa coefficients >0.61 are regarded as moderate to good (42). The data analysis was performed on a personal computer using SPSS software, version 12.0.1 (SPSS, Chicago, IL).

RESULTS

Participants and focus groups.

A total of 14 women and 17 men participated in this qualitative study. Five (16%) were retired and 9 (29%) were retired early due to the disease. Of the remaining 17 working participants (55%), 8 (47%) were blue collar workers. The mean ± SD age was 52.7 ± 11.1 years, and the mean ± SD disease duration of arthritis and psoriasis was 15.9 ± 12.9 years and 21.0 ± 15.3 years, respectively. Saturation was reached after 6 focus groups. The mean ± SD duration of the focus group sessions was 78 ± 11 minutes. The transcribed data resulted in 9,859 lines of text. In 590 meaning units in the transcribed data of the focus groups, we identified 198 subconcepts that were then grouped and assigned to 1 of the 54 concepts. These 54 concepts are presented in Tables 1, 2, and 3.

Table 1. Concepts from the focus groups in the components body function and structures and personal factors in comparison with the instruments*
ConceptICFAIMS-2SFBASDAIDASHDLQIDFIHAQHAQ-SPsAQoLSF-36
  • *

    Each concept from the focus groups was linked to the most precise ICF category using the same linking rules that have been developed to link health-status measures (36, 37) and concepts from qualitative studies of patients with rheumatoid arthritis to the ICF (11, 12). ICF = International Classification of Functioning, Disability and Health; AIMS2-SF = Arthritis Impact Measurement Scales Short Form; BASDAI = Bath Ankylosing Spondylitis Disease Activity Index; DASH = Disabilities of the Arm, Shoulder, and Hand; DLQI = Dermatology Quality of Life Index; DFI = Dougados Functional Index; HAQ = Health Assessment Questionnaire; HAQ-S = HAQ adapted for spondylarthropathies; PsAQoL = Psoriatic Arthritis–specific Quality of Life Instrument; SF-36 = Short Form 36 Health Survey; PF = personal factors; NC = not covered by the ICF; HC = health condition.

  • Concepts found not to be covered by any instruments.

  • Not yet developed.

Body image and appearanceb1801   X     
Sleepingb134X X      
Fatigueb130, b4552 X     XX
Emotional functionsb152X      XX
Painb280XXX     X
Sexual functionsb640   X     
Functions of the immune systemb430         
Biting foodb5101         
Structure and functions of the skins810, b8   X     
Sensations related to the skinb265, b840 XXX     
Structure of nailss830         
Structure, stability, and mobility of the (peripheral) jointss770, b710, b715XXX    X 
Structure, stability, and mobility of the spines7600, b710, b715, b720 X       
Structure and functions of movement-related muscless7702, b730, b735, b740  X      
Structure of the eyess220         
Structure of teeths3200         
Structure of external ears240         
Structure of maxillary air sinuss710         
Being in control of the diseasePF  X    X 
Own attitudes towards people with health problemsPF         
Loss of leisure timeNC         
Course of the diseaseHC        X
Table 2. Concepts from the focus groups in the component activities and participation in comparison with the instruments*
ConceptICFAIMS-2SFBASDAIDASHDLQIDFIHAQHAQ-SPsAQoLSF-36
  • *

    See Table 1 for definitions.

Mobilityd4X   XXXXX
Changing and keeping body positionsd410, d415X   XXX X
Getting in and out of a transportation meansd410    XXX  
Handling of gadgetsd440, d445  X XXX  
Lifting and carrying objectsd430X X  XX X
Fine motor skills of the handd440X    XX  
Use of arm and handd445X X XXX  
Driving a card4751X     X  
Self-cared5X X XXX X
Household activitiesd640X XXXXX X
Gardeningd6505  XX XX  
Shoppingd6200   X XX  
Relationship to family members and other peopled7X XX   X 
Paid work and productive activitiesd8X XXX X X
Sportsd9201X  X    X
Leisure activitiesd920X XX   XX
Table 3. Concepts from the focus groups in the component environmental factors in comparison with the instruments*
ConceptICFAIMS-2SFBASDAIDASHDLQIDFIHAQHAQ-SPsAQoLSF-36
  • *

    See Table 1 for definitions.

  • Concepts found not to be covered by any instruments.

Treatment and side effectse1101   X     
Food and nutritione1100         
Clothes, shoese1150   X     
Use of assistive devicese115X    XX  
Structure of buildingse155         
Loss of incomee1650         
Climatee225         
Support of wife/husband, familye310, e315X        
Use of a personal assistante340         
Attitudes of family memberse410X        
Attitudes of strangerse445         
Attitudes of colleaguese425         
Attitudes of health professionalse450         
Attitudes of hair dressere455         
Institutions of the health care systeme580         
Policies of health insurance companiese5802         

The kappa statistic for agreement in the linking of the concepts to the ICF between the 2 investigators was 0.74 (P < 0.0001). Therefore, the kappa coefficient exceeded the value 0.61 that has been regarded as moderate to good.

Literature search and instruments.

The literature search produced 14 hits in CINAHL, 2 in PsychINFO and Embase, and 556 in Medline. After the selection criteria for the articles were applied, 42 articles were reviewed in detail. Finally, 9 questionnaires were identified according to the selection criteria and were included in the analysis: the AIMS2-SF (25, 43, 44), the BASDAI (23), the DASH (28, 45), the DLQI (30), the Dougados Functional Index (DFI) (46), the HAQ (22, 24), the HAQ-S (29, 47), the PsAQoL (2), and the SF-36 (26, 27). The AIMS2-SF questionnaire includes 26 items and is the short form of the AIMS2 questionnaire, which has 78 items. The short form was selected because its use in a clinical setting is more feasible.

Comparison of concepts derived from the focus groups with the instruments.

The concepts and their representation in the instruments are shown in Tables 1, 2, and 3. The concepts are presented according to the ICF model: 19 concepts were linked to ICF categories in the component body functions and structures, 16 concepts were linked to ICF categories in the component activities and participation, and 16 concepts were linked to ICF categories in the component environmental factors. Two concepts were linked to the ICF component personal factors, the concept “course of the disease” was linked to the health condition itself, and the concept “loss of leisure time” was found not to be covered by the ICF. Of the 54 identified concepts, 19 concepts (35%) were found not to be covered by any of the instruments. These concepts are presented in Tables 1, 2, and 3.

Of these 19 concepts not covered by any of the instruments, 6 concepts (32%) linked to ICF categories in the component body functions and structures (Table 1). In the component environmental factors, 11 concepts (58%) were not covered by the instruments (Table 3). All concepts that were linked to categories in the ICF component activities and participation were found to be included in at least 1 of the instruments (Table 2). In the component personal factors, 1 concept was found not to be covered by the instruments. The concept “loss of leisure time,” which was not covered by the ICF, was also not represented in any of the instruments. Some patients reported that they lost considerable amounts of time because of frequent appointments with health care providers, including long waiting times, which finally led to a loss of leisure time because vocational responsibilities and tasks associated with housework and caring for children needed to be completed as usual in the remaining time.

DISCUSSION

In this qualitative study, we found that some concepts important to patients with PsA are not adequately covered by standard self-report instruments that are currently used to measure functioning in PsA. The first specific goal of this study was to explore the perspective of patients with PsA. Therefore, we first identified subconcepts in the meaning units of the transcribed data in order to stay close to what the patients actually said. Second, we grouped these subconcepts into several separate entities according to their meaning and assigned a concept that would comprise the meaning of all subconcepts. The subconcepts may show the different individual experiences of the patients, whereas the concepts may represent more general entities. This underscores our findings from an earlier study of patients with RA in which patients found that their individual experiences were not always acknowledged when more general concepts or outcomes were assessed (12).

The second specific goal was to determine which concepts important to patients are covered by the existing instruments assessing functioning. We used the ICF as a frame of reference to perform this comparison because it provides a general model of health that could be a frame of reference for both the focus groups and the instruments. The ICF has been successfully used in several studies to compare the content of different health status instruments (7, 38–40, 48) and in qualitative studies of patients with RA (12, 49) and knee osteoarthritis (50, 51). In our study, the ICF proved to be a useful reference to link concepts identified in patient focus groups to the instruments identified in the literature.

The third and fourth specific goals of this study were to identify issues important to patients that are currently not assessed using the existing instruments and to make recommendations for the further development of instruments. Several concepts were found not to be included in the instruments. Except for “biting food,” the concepts in the component body functions and structures that are not covered by the instruments (Table 1) may be considered to be included during any visit to clinics when a careful physical examination is performed and the patient's history is obtained by a physician or health professional.

Many concepts linked to ICF categories in the component environmental factors were not represented in the instruments. However, all of these contextual factors could be linked to the ICF. Therefore, developing a so-called ICF core set for PsA, which is a short list of relevant ICF categories specific for PsA, might be a possible approach towards including these contextual factors in health assessment. In the ICF component environmental factors, a scale allows each factor to be scored as either a barrier or a facilitator (32). In addition, we suggest developing a self-report instrument to assess the impact of individual environmental factors on participation in patients with PsA for use in practice and research.

Another suggestion is to modify an existing instrument by including an item to assess the concept “loss of leisure time.” A question for this item could be, “How satisfied are you with the amount of time you spend for leisure activities?” “Loss of time” may be an important concept if the impact of health or illness on daily life and participation in society is considered. Individuals with illness may have a societal disadvantage because they lose time for leisure activities compared with individuals without the disease.

The concept “own attitudes towards people with health problems” may represent a biographical process in relation to living with a disease rather than an outcome of a treatment. To focus interventions on biographical processes in relation to a rheumatologic disease may be extremely relevant for health professionals in practice and research. It may also be relevant if outcomes of psychological interventions are considered because it may represent how individuals view their own life situation. In a qualitative analysis that aimed to identify issues important to patients with RA and was conducted in a different country than the present study, similar themes were identified with regard to personal/intrinsic factors (being in control of the disease), future issues (course of the disease), and perceptions of normality (own attitudes towards individuals with health problems) (52).

Several concepts important to patients with PsA, such as body image and appearance, sexual functions, structure and functions of the skin, treatment and side effects, and clothes and shoes, are only covered by the DLQI. The DLQI may therefore be considered an obligatory instrument and should be included in all studies of patients with PsA.

All concepts linked to categories in the ICF component activities and participation were found to be covered in the instruments. However, no single instrument covered all concepts. Therefore, researchers and clinicians looking for instruments may want to first identify an outcome of interest according to the concepts relevant to patients with PsA and second select an instrument that covers the identified outcome. Our analysis demonstrates that some concepts are covered in more than one of the instruments, which may then be considered redundant if all questionnaires are included, e.g., in one trial or used in routine assessments. An example is the HAQ-S, which covers only one additional concept, namely, “driving a car,” which is not addressed by the HAQ. Except for driving a car, the HAQ-S may be considered redundant if the HAQ is used. Another example is the DFI, which covers no additional concepts compared with the HAQ-S.

The concepts identified in the focus groups may vary between different sociocultural contexts (51). Our study was conducted in a central European sociocultural context in Austria. Further research should therefore focus on the perspective of other societies and cultures. However, in the present study we aimed at presenting a methodology that could also be used in other sociocultural contexts and for other health conditions.

The impact of environmental factors, own attitudes towards individuals with health problems, and loss of leisure time may represent important aspects addressing participation that are currently not covered in the instruments assessing functioning in patients with PsA. Researchers and clinicians looking for instruments may first want to identify an outcome according to the concepts relevant to patients with PsA and may second select an instrument that covers the identified outcome.

AUTHOR CONTRIBUTIONS

Dr. Stamm had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study design. Stamm, Nell, Coenen, Aletaha, Machold.

Acquisition of data. Stamm, Mathis.

Analysis and interpretation of data. Stamm, Coenen, Taylor, Smolen, Machold.

Manuscript preparation. Stamm, Nell, Coenen, Stucki, Taylor, Smolen, Machold.

Qualitative analysis. Stamm, Coenen, Cieza.

Acknowledgements

We thank Sybille Schwarz from Munich, Germany, for assisting Michaela Coenen with performing the second linking of the concepts obtained in the focus groups to the ICF, and Herta Resch from Vienna, Austria, for her excellent transcriptions of the focus groups.

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