Disability Assessment with WHODAS 2.0 of People with Fibromyalgia in Poland: A Cross Sectional-Study

Introduction

Fibromyalgia (FM) is a multifactorial syndrome characterized by chronic widespread pain, fatigue, sleep and cognitive impairment, and functional symptoms [1,2]. It is estimated to affect 2% to 4% of people worldwide, with women being far more commonly affected [3,4]. Currently, the following American College of Rheumatology (ACR) diagnostic criteria for FM are used: a widespread pain index (WPI) score ≥7 and symptom severity (SS) scale score ≥5, or WPI score of 3 to 6 and SS score ≥9. For the diagnosis to be valid, symptoms should have been present at a similar level for at least 3 months, and the patient should have no other medical conditions that could have caused the symptoms [5].

Many factors influence the development of FM, including genetic predisposition, personal experiences, living environment, emotional-cognitive and inflammatory factors, mind-body relationship, and biopsychological ability to cope with stress [1,6–8]. The complexity and multisymptomatic nature of FM require a multidimensional assessment of various aspects of the patient’s life. They also cause the picture of functional limitations and the level of disability of patients with FM to vary widely [9].

As patients with FM experience chronic, multisystem pain, and chronic fatigue, and their symptoms are exacerbated by intense psychological stimuli or physical exertion, their quality of life and ability to perform multiple activities can be limited [10–12]. The greatest limitations in patients with FM are reported in motor activities, such as moving while performing everyday activities (eg, vacuuming), reaching, manipulating objects, coordinating movements, maintaining a steady pace, and making precise movements (eg, in the kitchen) [13].

The International Classification of Functioning, Disability and Health (ICF) defines disability as the result or outcome of a complex interrelationship between an individual’s health status, impairments of functions and structures, limitations in performing various activities, and personal factors and external (environmental) factors, in other words, the conditions in which the individual lives [14]. The World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) is a universal ICF-based tool for assessing the disability of people with various health problems [15]. Many studies have confirmed its effectiveness and reliability in assessing disability in various diseases [16,17].

The impact of FM on functioning and disability can be determined by standardized interview questionnaires. In Brazil, a mean disability score of 44.97 using the WHODAS 2.0 was shown among adults with FM [18]. The authors indicate that the WHODAS 2.0 is an accurate tool for assessing the functioning of patients with FM. Ashwini et al conducted an analysis of the health status of adults with FM in India and also reported a mean disability score (WHODAS 2.70 on a 5-point scale) [19]. Increased pain, anxiety, depression, and difficulty identifying and describing feelings were found to be predictors of higher levels of disability among patients with FM [20]. In contrast, a high level of social participation has been shown to reduce levels of disability and increase satisfaction with life [21].

The complexity of the causes and the multifaceted picture of limitations in functioning and disability requires a multimodal approach to FM treatment. Medical systems are under-equipped to meet the needs of patients with FM [22]. Individually tailored therapy is an important factor, given the increasing recognition that there are different subgroups of FM with different clinical characteristics [1]. A prerequisite for holistic assessment and improvement planning for FM patients is to assess their problems and limitations in daily life in order to formulate common, realistic treatment goals to which the patient will be motivated [23].

Recognizing the complexity of problems experienced by patients with FM and assessing functioning within a biopsychosocial model may improve the medical care of patients with FM. In Poland, the diagnosis, treatment, and support of patients with FM is still a huge challenge [24]. To the best of our knowledge, there is a lack of studies worldwide assessing the functioning of patients with FM using the ICF or tools built on it, such as the WHODAS 2.0.

Therefore, the purpose of this study was to assess disability and its associated factors. The study was conducted among 691 patients with FM in Poland, using an online survey.

Material and Methods

STUDY DESIGN:

This was a cross-sectional study of the functioning and disability of patients with FM aged 18 years and over in Poland.

ETHICS:

The study was approved by the Bioethics Committee of the University of Rzeszów (Resolution No. 2022/041). The study protocol was registered at (NCT06296446). All patients gave voluntary and informed consent to participate in the study.

SETTING:

The study was conducted from March to May 2024 in collaboration between the College of Medical Sciences of the University of Rzeszów, Lazarski University, and the National Association of Patients with Fibromyalgia (the FIBRO-MY). The FIBRO-MY members diagnosed with FM by a doctor and meeting ACR criteria were invited to participate in the study.

PARTICIPANTS:

Adult patients with FM living in Poland and affiliated with FIBRO-MY were included in the study.

PROCEDURES:

The study was conducted by means of an online Google questionnaire distributed to FIBRO-MY-affiliated adult patients via e-mail. Patients were placed in a closed group of FIBRO-MY members. The patients could complete the questionnaire only once. Prior to taking part in the study, each patient was informed about the aims and conduct of the study and gave informed consent to participate in the study. Each patient was required to confirm a statement that they had doctor-diagnosed FM and met the 2016 ACR criteria, before completing the online questionnaire. The inclusion criteria were as follows: a clinical diagnosis of fibromyalgia according to the current 2016 ACR criteria (WPI ≥7 and SS ≥5, or WPI=4 to 6 and SS ≥9; symptoms persisted at a similar level for a minimum of 3 months; no other medical conditions to explain the pain) [5], age 18 years or older, and informed consent to participate in the study.

The exclusion criteria were as follows: moderate to severe cognitive impairment, diagnosed neurological, oncological or other diseases in the active phase of the disease, history of orthopedic injuries and fractures within the last 3 months, and lack of patient consent to participate in the study.

VARIABLES:

Only patients who were diagnosed with FM by a doctor and met the 2016 ACR criteria were included in the analyses. As the study was anonymous and implemented through an online survey, the respondent could proceed to the actual part of the survey after confirming the statements used about the presence of diagnosed FM and the presence of ACR criteria. Respondents were excluded from the analysis if there was the presence of other diseases that could potentially influence the presence of generalized chronic pain (according to the ACR principle).

The main variable analyzed (the primary outcome) was the level of disability as measured by the WHODAS 2.0 questionnaire.

MEASUREMENT:

The WHODAS 2.0 36-item version was used to assess the disability of patients with FM. In addition, the Beck Depression Inventory (BDI) was administered. Furthermore, baseline metrics and health data, including the presence of other chronic diseases, were collected.

WORLD HEALTH ORGANIZATION DISABILITY ASSESSMENT SCHEDULE 2.0:

The WHODAS 2.0 v 36 is used to measure general disability and disability in 6 domains: domain 1, cognition (6 items); domain 2, mobility (5 items); domain 3, self-care (4 items); domain 4, getting along (5 items); domain 5, life activities (8 items), which is made up of 2 subdomains: 5.1, domestic activities and 5.2, work or school activities; and domain 6, participation in social life (8 items). Responses to the questions are rated on a 5-point scale indicating the level of difficulty or problem (1=none, 0–4%; 2=mild, 5–24%; 3=moderate, 25–49%; 4=severe, 50–95%; and 5=extreme or unable to do, 96–100%). The scores obtained were recalculated on a scale from 0 to 100, according to the user manual [25]. The very good psychometric properties of the WHODAS 2.0 36 item scale in individuals with fibromyalgia were confirmed in a separate study [16].

BECK DEPRESSION INVENTORY:

The BDI was used to assess the respondents’ emotional state. The BDI assesses affective, cognitive, somatic, and vegetative symptoms according to the criteria for major depression in the Diagnostic and Statistical Manual (DSM-IV). It contains 21 items on a 4-point scale ranging from 0 (no symptoms) to 3 (severe symptoms). The minimum score is 0 and the maximum score is 63. Higher scores indicate greater severity of symptoms. For those diagnosed with depression, scores of 0–13 indicate minimal depression, 14–19 mild depression, 20–28 moderate depression, and 29–63 severe depression [26–28].

METRICS:

The following data were collected using a metric questionnaire: age (in years), sex, place of residence, marital status, education, occupational status, number of comorbidities, number of drugs taken per day, benefit from rehabilitation in connection with FM, physical exercises, and level of pain as measured by the numeric rating scale (NRS).

BIAS:

Bias was reduced by the calculation of the sample size, dissemination of the survey questionnaire to FM patients affiliated with FIBRO-MY, and for patient confirmation of the diagnosis and presence of ACR criteria in order to enter the survey questionnaire.

STUDY SIZE:

A 4% share of patients with FM in Poland’s population of 37 million was assumed. The minimum sample size was assumed to be 600 patients with a maximum error of 4% and a confidence level of 95%. The survey was conducted among 695 patients, and 691 complete questionnaires were finally analyzed.

QUALITATIVE VARIABLES:

Qualitative variables were collected by the respondents completing a metric (eg, sex, place of residence, marital status, education, occupational status) and the BDI scale in an online questionnaire, which preceded the actual disability level survey using the WHODAS 2.0.

The following qualitative variables were collected: sex, place of residence, marital status, education, occupational status, benefit from rehabilitation in connection with FM, physical exercises, level of depression (BDI). A qualitative variable was also determined by the level of disability using the WHODAS 2.0.

STATISTICAL ANALYSIS:

The data collected were analyzed using TIBCO Statistica data analysis software system version 13. The number and percentage (%) for categorical variables or the mean±standard deviation (SD) for measurable variables were used for initial data analysis. The normality of the distribution of the measurable variables was tested using the Shapiro-Wilk test. Due to the non-normality of the distribution of measurable variables, the Spearman rank correlation coefficient significance test (when sociodemographic variables were quantitative), the Mann-Whitney U test (when sociodemographic variables were qualitative and 2 categories), and the Kruskal-Wallis test (when sociodemographic variables were qualitative and a minimum of 3 categories) were used to assess the influence of individual sociodemographic variables on the level of disability in the study population. A linear regression model was used to examine the combined effect of factors on the general level of disability and the level of disability in specific domains. Regression coefficients with confidence intervals and corresponding significance levels for the coefficients are given. The level of statistical significance was taken at P<0.05.

Results

CHARACTERISTICS OF THE STUDY POPULATION:

The average age of the patients surveyed was 44.21 years. Most patients were women (94.50%), living in urban areas (77.57%), living with a spouse or partner (72.65%), with secondary or higher education (92.62%), and working (64.98%). The average number of diagnosed comorbidities was 8.44. The patients had a high average value of subjectively experienced pain on the NRS scale (7.64). More than half of the patients took 4 or more medications (53.98%) and used rehabilitation for fibromyalgia (51.37%). As shown in Table 1, almost 2 out of 5 patients did not perform any physical exercises. More than half of the patients had a severe level of depression (52.24%).

ASSESSMENT OF THE GENERAL LEVEL OF DISABILITY AND LEVEL OF DISABILITY IN SPECIFIC AREAS:

A severe level of disability measured by the WHODAS 2.0 was found in the study group (mean=49.69; SD=19.19). As shown in Table 2, the greatest restrictions were found in the following areas: domain 5.1, life activities: household activities (mean=73.43; SD=28.41); domain 6, participation in social life (mean=64.59; SD=23.40); and domain 2, mobility (mean=62.07; SD=25.52).

EFFECT OF INDIVIDUAL SOCIO-DEMOGRAPHIC VARIABLES ON THE GENERAL LEVEL OF DISABILITY AND LEVEL OF DISABILITY IN SPECIFIC DOMAINS:

The categorical sociodemographic variables that statistically significantly differentiated the respondents in terms of the level of disability were professional status (unemployed patients had the highest level of disability), number of medications taken (patients taking 4 or more medications had the highest level of disability), and level of depression (patients with severe depression had the highest level of disability). The level of disability increased significantly with the increase in measurable variables, namely, subjectively perceived level of pain and number of comorbidities (Table 3).

Occupational status significantly influenced the general level of disability (unemployed patients had a level of disability on average 3 points higher than employed patients), and domains 3, 5.2, and 6, were statistically significantly higher for the unemployed relative to the others for these domains (between 2.68 and 5.91 points) and statistically significantly lower for retirees than for the employed for domain 5.2 (by 11.25 points) (Table 4).

The number of comorbid diseases significantly affected the level of disability only in domain 6, participation in social life.

Subjectively perceived pain levels determined higher general disability levels (by an average of 3.03 points per NRS score) and across all domains, with a 1-point increase in subjectively perceived pain levels resulting in an average increase in disability levels from 2.06 points (domain 1) to 3.86 points (5.1) (Table 4).

The number of drugs taken significantly influenced the patients’ general level of disability (those taking 2–3 drugs/day had an average of 2.60 points higher level of disability than those taking a maximum of 1 drug/day) and for domains 2, 5.1, 5.2, and 6, the level of disability was statistically significantly higher for those taking 2–3 drugs/day relative to those taking 0–1 drug/day, from 3.40 points (domain 6) to 4.53 points (domain 2) (Table 4).

The severity of depression significantly influenced the general level of disability, whereby, for all domains, patients with severe depression had a disability level on average 7.77 points higher than patients with at most mild depression. The level of disability was statistically significantly higher for those with severe depression than for those with at most mild depression, from 6.15 points (domain 2) to 13.90 points (domain 4), and for domain 6, disability was 2.72 points higher for those with moderate depression than for those with at most mild depression (Table 4).

Discussion

STRENGTHS AND LIMITATIONS OF THE STUDY:

The strengths of this study were the large population of patients with FM surveyed and the nation-wide nature of the survey. The survey also had some limitations. As a cross-sectional survey, it did not allow causal relationships to be established; however, the model we used allowed us to determine the effect of the individual factors included in the survey on the level of disability. Another limitation was the low representation of men in the study. Future research should focus more strongly on the problem of disability in men with FM. Another limitation of the study was the methodology used, which involved the use of an online self-completed questionnaire. Future research should consider implementing methods of direct functional assessment of patients with FM.

Conclusions

The findings from this study showed that the level of disability among patients with FM in Poland is significant. The main variables influencing the level of disability were found to be professional status, level of pain, number of medications taken, and level of depression. Understanding the determinants of disability in FM can contribute to the development of effective therapies and symptom relief. In view of the increasing recognition of chronic pain syndromes, often occurring without an identifiable cause, and the low effectiveness of pharmacological treatment, it is necessary to broaden the perspective of assessing the functional status and problems of patients, based on the biopsychosocial model of disability proposed by the World Health Organization. Further research in this area is needed.