Abstract
Objective. The effect of a disease can be categorized by a standardized reference system: the International Classification of Functioning, Disability and Health (ICF). The objective was to map the effect of psoriatic arthritis (PsA) from the patient’s perspective to the ICF.
Methods. A systematic literature review was performed. Qualitative publications reporting domains of impact important for patients with PsA were identified using the following terms: (“psoriatic arthritis”) AND (“quality of life” OR “impact”). Meaningful concepts were extracted from the publications, grouped into domains and linked to the ICF categories. The number of concepts linked to each ICF category and to each ICF level was calculated. The number of concepts not linkable was also calculated.
Results. Eleven studies (13 articles) were included in the analysis. Twenty-five domains of impact were cited, of which the ability to work/volunteer and social participation were the most cited (both by 10 studies). In total, 258 concepts were identified, of which 217 could be linked to 136 different ICF categories; 41 concepts, mostly personal factors, could not be precisely linked. The most represented ICF component was activities and participation (42.6%) rather than body structures (10.3%) or body functions (29.4%). Ten studies (90.9%) reported impairments in the ability to work/volunteer and social participation, and 7 (63.6%) reported leisure activities, family and intimacy, pain, skin problems, and body image.
Conclusion. PsA widely affects all aspects of patients’ lives, in particular aspects related to activities and participation. The ICF is a useful approach for the classification of disease effect.
- PSORIATIC ARTHRITIS
- PATIENT PERSPECTIVE
- INTERNATIONAL CLASSIFICATION OF FUNCTIONING, DISABILITY AND HEALTH (ICF)
- QUALITY OF LIFE
- SOCIETAL BURDEN
- EMOTIONAL FUNCTIONS
Psoriatic arthritis (PsA) is a heterogeneous disease with a major effect on patients’ lives1,2,3,4. In PsA, the range of problems experienced by patients is broad and involves basic day-to-day activities, work and leisure activities, and community participation roles5. The effect of a disease can be better assessed from the patient’s perspective by qualitative studies because they can identify patients’ experiences6. There are several studies to assess the patient’s perspective regarding the effect of PsA7,8,9,10. Although some aspects such as pain, skin, or functional disability are frequently cited, others such as fatigue are more rarely cited11. Overall, it is difficult to obtain an overview of the effect of PsA. Therefore, it would be of particular interest to categorize this effect by relating it to a universally accepted, standardized reference system.
The International Classification of Functioning, Disability and Health (ICF) has been developed and endorsed by the World Health Organization as the standard language and classification system for functioning and disability12. In the ICF, functioning and disability are multidimensional concepts. Both are umbrella terms for body function, body structures, and activities and participation. They denote the positive or neutral aspects (for functioning) or negative aspects (for disability) of the interaction between a person’s health condition(s) and that individual’s contextual factors (environmental and personal factors)12.
The ICF can be used as a reference framework, allowing a researcher or a group of experts assigned to develop a set of recommendations to see which domains of functioning/disability are covered by a specific set of domains of impact and vice versa13. Linking rules are available to standardize the process of connecting outcome measures to the ICF classification14,15. Linking domains of impact in PsA to the ICF would allow us to structure and categorize the effect of PsA and to compare it with other diseases. Further, this linking may reveal limitations of the ICF, i.e., domains that are important for patients but are not covered by the ICF14,16,17,18. A study assessed the effect of PsA in patients with PsA according to the ICF categories, but the sample size was small (94 patients) and did not reflect the overall effect that can be assessed through a systematic literature review19.
The objective of our work was to assess the patient-perceived effect of PsA through a systematic literature review and to map this effect to the ICF.
MATERIALS AND METHODS
Identification of publications with domains of impact important for patients with PsA
A systematic literature review was conducted by 1 person (TG) in the PubMed/Medline and Embase databases on March 6, 2015. Publications were identified through a search that used the following terms: (“psoriatic arthritis”) AND (“quality of life” OR “impact”), with a limitation to “Humans,” “all adults: 19+ years,” and “English,” but with no limitation of time. Articles were also searched among any available unpublished work from recent congresses and among references of included articles. Only studies related to the effect of PsA from the patient’s perspective were included, i.e., studies with a qualitative design or a qualitative component. The detailed methodology is presented in Supplementary Table 1 (available with the online version of this article).
The quality of the included studies was assessed according to the Critical Appraisal Skills Program checklist20 for qualitative studies and the National Heart, Lung and Blood Institute checklist21 for quantitative studies.
Identifying domains of impact important for patients with PsA and extracting corresponding concepts
Domains of impact were identified by 2 people (TG, LG) in the studies included in the systematic literature review. A domain was defined according to the Outcome Measures in Rheumatology recommendations as referring to relevant areas of outcome in rheumatology outcome studies22,23. To avoid confusion related to terminology, because second-level ICF categories are also called “domains of health,” it was decided to name the domains identified in the studies as “domains of impact” and the units of the ICF only as “components” and “categories”. Concepts were also generated from these sources. A concept was defined as 1 separate meaningful entity, such as a body structure, a body function, an activity, or a contextual factor7. An example of how this step was performed can be found in Supplementary Table 1 (available with the online version of this article).
Linking concepts to the ICF
The ICF part 1 covers functioning and disability and includes the components body functions, body structures, and activities and participation. Part 2 covers contextual factors and includes the components environmental factors and personal factors. The ICF consists of multiple categories in each of these sections12. The detailed structure of the ICF is described in the Supplementary Table 1 (available with the online version of this article).
The identified concepts were linked to the ICF categories. The linking process was performed separately (blinded) by 2 independent raters (TG, UK) and a third rater for adjudication (LG) according to the updated linking rules15 (Supplementary Table 1, available with the online version of this article). Some concepts that cannot be precisely linked are considered as not linkable by the ICF15. Concepts that were linked to the ICF domain personal factors could not be linked to categories because personal factors are not yet classified in the ICF13,15.
RESULTS
Systematic literature review
In all, 643 publications were identified by the systematic literature review: 239 in PubMed/Medline and 404 in Embase. After removing duplicates, 460 publications were retained and screened, and 2 articles were added by hand search: 1 from the references of included articles and 1 from the professional meetings. Twelve articles and 1 congress abstract were included in our final analysis (Figure 1)10,24,25.
Of these 13 publications, 8 were exclusively on PsA7,9,10,24,25,26,27,28 whereas the other 529,30,31,32,33 included patients with PsA and also patients with psoriasis (PsO) without arthritis (Table 1)7,9,10,24,25,26,27,28. Only 5 studies were qualitative per se; the other studies used qualitative work in the development of questionnaires and some of them did not precisely define the population involved in their qualitative phases, so the evaluation in these cases was difficult (Table 1).
Domains of impact important for patients with PsA and extracting corresponding concepts
Ten studies (90.9%) reported on the ability to work/volunteer and social participation, and 7 (63.6%) reported on leisure activities, family and intimacy, and other domains such as pain, skin problems, and body image. Joint problems were reported in almost half of the studies (45.5%).
Linking concepts to the ICF
In total, 258 concepts were extracted, of which 217 (84.1%) could be linked to the ICF categories. The agreement between raters was high (87.2%).
The 217 concepts were linked to 136 distinct ICF categories, of which 14 (10.3%) were part of body structures, 40 (29.4%) body functions, 58 (42.6%) activities and participation, and 24 (17.6%) environmental factors (Figure 2).
There were some differences regarding the number of the ICF categories and components when comparing by the type of study. In purely qualitative studies, concepts were linked to 92 ICF categories, the most represented ICF component being activities and participation (39.1%), followed by body functions (29.3%), environmental factors (20.7%), and body structures (10.9%). In studies with both quantitative and qualitative phases, concepts could be linked to 84 ICF categories, and activities and participation was also the most represented component (44.1%). Body functions represented 34.5%, environmental factors 14.3%, and body structures 7.1%.
There were also some differences when comparing studies by the type of patients involved. In the studies including patients with PsA and also patients with PsO without arthritis, 56 ICF categories were linked, while in the studies involving patients with only PsA, 117 ICF categories were linked. Activities and participation was the most represented ICF component in the studies involving patients with PsO with or without arthritis (48.2%), followed by body functions (30.3%), body structures, and environmental factors (3.6% each). On the other hand, in the studies exclusively on PsA, the proportion of ICF categories in activities and participation and body functions was not as different: 37.6% and 30.7%, respectively. Environmental factors represented 19.7% and body structures 12%.
Frequency of ICF categories
In total, 344 second-level ICF categories were identified among all included studies. The most frequent second-level ICF categories for each ICF component and their corresponding linked concepts are depicted in Table 2. The most frequent second-level category was b152: emotional functions (reported 45 times, i.e., 13% of 344), followed by d920: recreation and leisure (23 times, i.e., 6.7%). Also cited frequently were b134: sleep functions, and b455: exercise tolerance functions, each with a cumulative frequency of 14 (4%).
Fatigue was also cited frequently. However, it was difficult to link the concept of fatigue to the ICF because there is no ICF category that reflects its entire meaning as seen from the perspective of patients with PsA. Thus, fatigue was linked to both b130: energy and drive functions and b455: exercise tolerance functions, reflecting both physical and psychological aspects of fatigue.
Levels of linking
Almost half of the concepts were linked to second-level ICF categories (67 out of 136, 49.2%). The ICF component that had the most specific categories (higher level) was body structures, with 57.2% of the concepts being linked to third- and fourth-level categories — mainly related to joint problems.
On the contrary, activities and participation had no fourth-level categories; however, half of them were third-level and covered a broad spectrum of domains of impact important for patients with PsA.
The majority of the ICF categories from body functions were second-level categories (52.5%). However, this might reflect limits of the ICF, because many of the concepts were named by patients at a higher level of specification, but with no appropriate match in the ICF. For example, various concepts related to skin problems, such as “itching related to skin,” “burning/flares related to skin,” “tightness of the skin,” and “pulling or stinging in your skin,” were all linked to the same second-level ICF category, namely b840: sensation related to skin.
Concepts that could not be precisely linked to the ICF
In all, 41 concepts (15.9%) could not be precisely linked to ICF categories. Most of these non-linkable concepts were personal factors (21 concepts, 51.2% of 41) and were mainly related to coping with the disease, e.g., “talking about the disease” and “hiding nails because of appearance”. Patients reported various ways of managing the disease: accepting and learning to live with the disease, turning coping into a daily routine, talking about the disease, hiding symptoms or avoiding certain situations and activities, and adjusting to the disease9,27,33. Finding positive aspects of the disease were also reported: changing priorities in life, opportunity to reflect, discover creative activities, or doing sports27,33.
Other concepts that could not be specifically linked were either “not definable” (6 concepts; e.g., “joint discomfort,” “not being able to keep people’s pace”) or “not covered” (14 concepts; e.g., “choices of a life of their own,” “feeling older than one’s age,” “taking a sick leave”).
DISCUSSION
Our study allows us to obtain an overview of the effect of PsA from the patient’s perspective and to map this effect to the ICF. The effect of PsA is widely spread across aspects of quality of life, thus modifying not only physical aspects of life but also psychological and social aspects34. Social aspects appear of particular importance to patients: the most frequently reported domains of impact were the ability to work and social participation. Further, activity and participation was the most represented ICF component in PsA (42.6%) and was much more frequent than body structures (10.3%), body functions (29.4%), and environmental factors (17.6%). In terms of cumulative frequency, the most frequently cited ICF categories were b152: emotional functions and d920: recreation and leisure. Sleep, fatigue, pain, and skin problems were also frequently reported. Linking was a higher level (more precise) for body structures. Although linking to the ICF allowed a more precise assessment of the disease effect, it is noteworthy that almost 16% of concepts could not be specifically linked to any of the ICF categories.
The identified concepts could be linked to all components of the ICF, confirming that the effect of PsA is wide-reaching and is spread across all aspects of life. To our knowledge, there is no similar attempt in the published literature to link all qualitative-based work assessing the effect of other rheumatic diseases, i.e., rheumatoid arthritis (RA) or ankylosing spondylitis (AS), to the ICF. Therefore, no direct disease comparison is possible. However, results from the ICF Core Sets for RA16 and AS35 showed that the most affected components were body structures and body functions: 44.9% in RA and 52.5% in AS.
Similar results in PsA were reported in a study of 94 patients from 5 countries19: more than half of the affected categories were classified into the activity and participation component compared with only a third in a methodologically similar study of patients with RA36 and 45% in AS37. These results may reflect a higher societal effect of PsA, probably due to the additional burden of the skin disease and its consequences, knowing that PsO skin disease is socially disabling38,39,40.
Activities and participation was found to be well represented, irrespective of study type. However, in qualitative studies, body structures as well as environmental factors had a higher proportion than in the studies with both quantitative and qualitative methodology. This might be because in the latter, the qualitative work preceding the development of the questionnaires was presented in a lesser extent compared with exclusively qualitative studies. Detailed results from qualitative studies are important in assessing disease effect because they can better identify patients’ perspective. Additionally, in studies exclusively on PsA, the difference in proportion of ICF categories was not that significant for body functions and activities and participation as for studies involving patients with PsO with or without arthritis. Moreover, body structures were far more represented in studies with patients with only PsA, probably due to the additional burden of musculoskeletal involvement. This also strengthens the idea that the wide effect of PsA comes from its having both skin and articular components. PsA was found to lead to significant psychological consequences.
The second-level ICF category “emotional functions” was frequently reported and it was linked to a very wide range of concepts: anxiety, fear, uncertainty, sadness, depression, lack of motivation, irritation, frustration, anger, etc. This reflects the high psychological burden of PsA, which may be partly explained by the impairment in social participation and relationships. Difficulties in linking psychological concepts reflect limitations of the ICF in discriminating categories of feelings. Highly specific information that is important for patients with PsA might be lost and reduced to only 1 emotional dimension, which is a major limit of the ICF and was also observed in RA16,41.
A number of concepts (41, 15.9%) could not be precisely linked to the ICF categories, similar to other studies18,42, indicating the limitations of the ICF. Most of the non-linkable concepts were personal factors, namely coping with the disease. This underlines the underestimated importance of coping strategies in patients with PsA.
It was difficult to compare the linking process to other studies, i.e., to bring information about discrepancies and similarities of concepts previously linked to the ICF because previous studies used different methodologies17,18 or provided information from qualitative work43. There was only 1 situation where the same linked ICF categories were “re-used,”7 and some difficulties in linking were common, i.e., concepts such as “fatigue,” different aspect of “emotional problems,” or various personal factors were difficult to link.
Our current study is subject to several limitations. Studies exclusively assessing the effect of PsO alone were not included in the systematic literature review, leading to a potential loss of information, considering that, because of the additional burden of the arthritis, the effect of PsA is different from the effect of PsO solely. Nevertheless, to be more inclusive on domains of impact, studies on PsA with or without some patients with only PsO were taken into consideration. Another weakness of our current analysis is the lack of more detailed information regarding the qualitative work preceding the development of the questionnaires assessing the effect of PsA compared with the qualitative studies where the patient’s perspective was extensively presented. This lack of information also hindered the assessment of quality and the risk of bias of the included studies. However, because data on the effect of PsA from the patient’s perspective are few, adding results from the qualitative phase of questionnaire development brings a wider perspective on the effect of PsA as reflected from the patient’s point of view. Additionally, not all the studies included in the systematic literature review assessed the whole effect of PsA. Some of the studies were focused on specific aspects of effect, such as nail involvement30 or leisure29. This might explain the high cumulative frequency of the second-level ICF category d920: recreation and leisure. Nevertheless, this domain was cited in 63.6% of the studies included in our analysis, demonstrating its importance attributed by the patients.
Another limitation is the lack of assessment of the association between specific disease characteristics and patient-reported effect. However, this is a limitation of qualitative studies in general.
These limits have already been pointed out in previous studies7,14,15,18,41: those due to the linking process, i.e., concepts that cannot be precisely linked to the ICF, personal factors that are not classified, the impossibility of differentiating between activities and participation, and the difficulty of linking concepts such as fatigue or various emotional feelings. Despite its flaws, the ICF has the advantage of being a standardized reference system, allowing the structuring/categorizing of effect and comparison across diseases13.
PsA widely affects all aspects of patients’ lives, in particular regarding activities and participation, reflecting the functional limitations and societal burden of PsA. These results will be of interest for the assessment of patients living with PsA.
ONLINE SUPPLEMENT
Supplementary material accompanies the online version of this article.
Acknowledgment
We thank Penelope Palominos (Porto Alegre, Brazil) for comments and suggestions that improved the manuscript.
- Accepted for publication November 11, 2016.
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