Abstract
The Influence of Rheumatism on Health and Lifestyle (known natively in Dutch as the Invloed van Reuma op Gezondheid en Leefwijze, abbreviated as IRGL) is a multidimensional, disease-specific self-report assessment tool designed to evaluate the physical, psychological, and social dimensions of health status in individuals diagnosed with chronic rheumatic disorders. Developed in the Netherlands by C. J. E. A. Huiskes, Floris W. Kraaimaat, and Johannes W. J. Bijlsma in 1990, the instrument was conceptualized partly as an adaptation and clinical extension of the Arthritis Impact Measurement Scales (AIMS), tailored specifically to capture the distinct illness trajectories, coping demands, and functional limitations characteristic of patients with chronic joint diseases such as rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis.
The IRGL comprises 16 overarching question clusters encompassing 68 discrete items organized across four principal health domains: physical functioning, psychological functioning, social functioning, and the overarching impact of rheumatic disease on daily life. A distinctive psychometric feature of the IRGL is its differential temporal framing: items assessing physical functioning refer to the patient's experiences over the preceding month, psychological functioning items encompass both the past week (affective states) and the past month (broader psychological well-being), and social functioning items evaluate interpersonal dynamics over the preceding six months. Responses are recorded on standardized Likert-type scales ranging from 4-point to 5-point formats. Extensive psychometric evaluations indicate high internal consistency across subscales (Cronbach’s $\alpha$ coefficients typically ranging from .70 to .92), satisfactory test-retest reliability across multi-week intervals, robust convergent validity with functional capacity measures such as the Health Assessment Questionnaire (HAQ), and demonstrable sensitivity to clinical change resulting from pharmacological and behavioral interventions.
Keywords
Invloed van Reuma op Gezondheid en Leefwijze, IRGL, rheumatoid arthritis, health-related quality of life, psychometrics, physical functioning, psychological adjustment, social support, patient-reported outcome measures, biopsychosocial assessment
Authors
The IRGL was developed through a multidisciplinary collaboration between clinical psychologists and rheumatologists in the Netherlands:
- C. J. E. A. Huiskes, Ph.D. — Department of Clinical Psychology and Health Psychology, Utrecht University, Utrecht, Netherlands.
- Floris W. Kraaimaat, Ph.D. — Professor Emeritus of Clinical Psychology, Department of Medical Psychology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands; formerly of Utrecht University.
- Johannes W. J. Bijlsma, M.D., Ph.D. — Professor Emeritus of Rheumatology, Department of Rheumatology and Clinical Immunology, University Medical Center Utrecht (UMC Utrecht), Utrecht, Netherlands.
Correspondence concerning the original development of the instrument historically centered at the Department of Rheumatology and Clinical Immunology, University Hospital Utrecht, and the Department of Clinical Psychology, Utrecht University, Netherlands.
Purpose
Chronic rheumatic diseases represent a major etiology of persistent pain, progressive physical disability, emotional distress, and societal participation restriction worldwide. Traditional biomedical markers in rheumatology—such as erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), radiologic joint space narrowing, and joint counts—frequently correlate only modestly with a patient's subjective experience of pain, daily functional impairment, and psychological distress. To bridge the gap between biological disease activity and the patient's lived experience, clinical researchers require validated patient-reported outcome measures (PROMs) that capture health-related quality of life (HRQoL) across multiple life spheres.
The primary purpose of the Influence of Rheumatism on Health and Lifestyle (IRGL) is to provide a standardized, psychometrically rigorous self-assessment profile of the physical, psychological, and social consequences of rheumatic illnesses. The instrument was deliberately constructed to overcome limitations observed in direct translations of foreign questionnaires, such as the original American Arthritis Impact Measurement Scales (AIMS). The developers identified that linguistic translation alone failed to account for Dutch healthcare structures, sociocultural norms surrounding independence, and specific communicative practices regarding chronic pain and social support.
Clinically, the IRGL serves several vital purposes:
- Multidimensional Baseline Profiling: It enables rheumatologists, clinical psychologists, physical therapists, and occupational therapists to systematically quantify the unique balance of physical impairments, psychological distress, and social resource depletion present in an individual patient at initial presentation.
- Treatment Planning and Personalization: By distinguishing between purely physical deficits (e.g., restricted mobility or manual dexterity) and psychological burdens (e.g., anxiety or depressed mood), the IRGL guides personalized treatment paradigms—indicating whether a patient primarily requires medical-pharmacological titration, physical rehabilitation, or targeted psychological interventions such as cognitive-behavioral therapy (CBT).
- Monitoring Disease Progression and Intervention Efficacy: The instrument is sensitive to longitudinal changes, permitting healthcare teams to track the holistic impact of disease-modifying antirheumatic drugs (DMARDs), biologic therapies, multidisciplinary rehabilitation programs, and chronic disease self-management education over time.
- Epidemiological and Health Services Research: The IRGL provides clinical researchers with reliable, population-normed continuous outcome metrics to assess the relative burden of diverse musculoskeletal pathologies (e.g., comparing rheumatoid arthritis with fibromyalgia or systemic sclerosis) and to model the determinants of workforce participation and healthcare utilization.
Psychological Construct
The IRGL is conceptualized as an operationalization of multidimensional health status within the framework of chronic physical illness. Rather than yielding an oversimplified, unweighted composite score, the instrument posits that health status in chronic rheumatism consists of distinct, interrelated sub-constructs operating within physical, psychological, and social domains. Each domain is decomposed into specific, clinically grounded subscales:
1. Physical Functioning Domain
Physical disability in rheumatic disease manifests across distinct biomechanical systems. The IRGL isolates these patterns into dedicated subscales, evaluated with reference to the preceding month:
- Mobility: Assesses gross motor functioning, lower extremity capability, and geographical range of movement. This subscale measures the degree to which joint pain and stiffness restrict the individual's capacity to walk outdoors, use public or private transportation, climb stairs, and maintain independent locomotion.
- Self-Care: Quantifies basic activities of daily living (ADL), focusing on personal maintenance tasks such as dressing oneself, bathing, using the toilet, and getting in and out of bed. High scores denote profound physical dependency on human assistance or assistive devices.
- Dexterity: Targets fine motor performance and upper extremity joint involvement (hands, wrists, elbows). Items evaluate tasks such as turning door handles, opening containers, writing, buttoning garments, and manipulating small household objects.
2. Psychological Functioning Domain
Chronic unpredictable pain and impending functional decline evoke diverse affective reactions. The IRGL operationalizes psychological functioning not merely as the absence of psychopathology, but as an interplay between negative affectivity and positive psychological resources:
- Anxiety: Assesses somatic and cognitive manifestations of acute and chronic apprehensive worry, tension, nervousness, and psychophysiological arousal experienced over the previous week.
- Depressed Mood: Measures dysphoria, feelings of hopelessness, loss of interest, lethargy, and gloominess over the previous week. This component identifies depressive symptomatology precipitated by chronic pain and perceived loss of autonomy.
- Positive Affect / Well-Being: In contrast to standard medical deficit models, the IRGL incorporates assessments of optimism, cheerfulness, perceived vitality, and life satisfaction, reflecting the psychological resilience emphasized in contemporary health psychology.
3. Social Functioning Domain
Recognizing that rheumatic disorders severely impact interpersonal relationships, role fulfillment, and community integration, the IRGL evaluates social constructs over a six-month recall interval:
- Social Network Extent: Quantifies the structural aspects of social relationships, including the frequency of interpersonal contacts, the size of the active social circle, and involvement in social organizations or community networks.
- Perceived Social Support Received: Measures functional social exchange, evaluating the extent to which the patient receives instrumental aid (practical assistance with domestic or personal tasks), informational guidance, and emotional validation from family members, friends, and peers.
- Satisfaction with Social Support: A purely qualitative appraisal of whether the support received corresponds to the individual’s subjective needs. The developers emphasized that high volumes of unrequested support can induce feelings of guilt or diminished self-worth; hence, support satisfaction is treated as an independent psychometric construct from received support volume.
4. Disease Impact and Pain
In addition to functioning within traditional life spheres, the instrument captures disease-specific symptoms that directly influence lifestyle:
- Pain Severity and Frequency: Assesses average daily joint pain, peak pain episodes, nocturnal pain waking the patient, and the subjective unpleasantness of persistent musculoskeletal discomfort.
- Lifestyle Restriction / Role Disruption: Evaluates the degree to which rheumatic illness forces unwanted modifications in vocational performance, domestic obligations, leisure pursuits, intimacy, and long-term life plans.
Theoretical Framework
The design and conceptual architecture of the IRGL are grounded in three prominent theoretical paradigms: George Engel's Biopsychosocial Model, Richard Lazarus and Susan Folkman's Transactional Theory of Stress and Coping, and the functional disability frameworks codified by the World Health Organization.
The Biopsychosocial Paradigm
Historically, rheumatologic evaluation relied heavily on a biomedical reductionist framework, which assumed a direct, linear relationship between joint inflammation and clinical impairment. By contrast, the IRGL was engineered under the biopsychosocial premise that disease manifestation is modulated by complex, reciprocal interactions between biological variables (e.g., synovial inflammation, cartilage destruction), psychological factors (e.g., catastrophic interpretation of pain, affective vulnerability, perceived control), and social contexts (e.g., marital dynamics, workplace accommodations, social reinforcement of illness behaviors). Consequently, evaluating a patient's health requires independent yet concurrent quantification across physical, psychological, and social axes.
Transactional Stress and Coping Theory
The IRGL draws heavily upon Lazarus and Folkman’s conceptualization of stress as an ongoing transaction between the person and their environment. Chronic rheumatic conditions represent a continuous, unresolvable ambient stressor characterized by pain exacerbations (flares), functional fluctuations, and progressive somatic losses. Under this model:
- Primary Appraisal: The patient assesses the threat posed by symptoms (reflected in the IRGL pain and lifestyle impact subscales).
- Secondary Appraisal: The patient evaluates their personal and external coping resources to manage this threat. The IRGL operationalizes these coping resources through its measurement of positive affect, active social networks, and satisfying social support systems.
- Emotional and Behavioral Outocmes: Maladaptive transactions lead to anxiety, depression, and social alienation, whereas effective buffering mechanisms preserve well-being despite physical limitations.
Integration with Disability Classifications
The instrument aligns conceptually with the progression from impairment to disability and handicap, which formed the foundation of the original International Classification of Impairments, Disabilities, and Handicaps (ICIDH) and subsequent International Classification of Functioning, Disability and Health (ICF). The IRGL explicitly separates basic physical impairments (joint stiffness, fine motor limitations) from activity limitations (dressing, walking) and participation restrictions (social isolation, disruption of occupational roles), providing a coherent taxonomical framework for clinical analysis.
Validity
The validity of the IRGL has been thoroughly demonstrated across numerous psychometric investigations involving cohorts of patients with rheumatoid arthritis, osteoarthritis, fibromyalgia, and ankylosing spondylitis.
Construct and Convergent Validity
Construct validity has been established by demonstrating that the IRGL subscales correlate in predicted directions with established external reference standards:
- Physical Functioning: The IRGL Mobility, Self-Care, and Dexterity subscales demonstrate robust, statistically significant correlations ($r = .65$ to $.82$, $p < .001$) with the Dutch version of the Health Assessment Questionnaire (HAQ) Disability Index and the physical functioning dimensions of the original AIMS. Furthermore, these scales correlate moderately with physician-rated global functional class according to the American College of Rheumatology (ACR) criteria ($r = .50$ to $.68$).
- Psychological Functioning: The Anxiety and Depressed Mood subscales exhibit strong positive correlations with the Hospital Anxiety and Depression Scale (HADS) and the Symptom Checklist-90-R (SCL-90-R) anxiety and depression subscales ($r = .68$ to $.78$). The Positive Affect scale correlates positively with measures of dispositional optimism (Life Orientation Test) and negatively with chronic neuroticism.
- Disease Activity and Pain: The IRGL Pain scale correlates strongly with Visual Analogue Scales (VAS) measuring current and retrospective pain intensity ($r = .70$ to $.85$) and moderately with clinical disease activity indices such as the Disease Activity Score (DAS28).
Discriminant Validity
Discriminant validity is supported by findings that the physical functioning subscales correlate substantially lower with psychological distress scales ($r = .18$ to $.32$) than with objective mobility tests (e.g., timed walk tests). Conversely, biological markers of acute inflammation (ESR, CRP) correlate significantly with IRGL pain and physical function, but exhibit negligible correlations ($r < .15$) with the IRGL social support and positive affect subscales, demonstrating that the psychological and social subscales capture unique variance that cannot be explained by inflammatory activity alone.
Predictive and Longitudinal Validity
Longitudinal prospective cohort studies led by researchers such as Evers, Kraaimaat, and colleagues (e.g., Evers et al., 1998, 2003) confirmed the predictive validity of the IRGL. Baseline scores on the IRGL psychological functioning subscales predicted long-term physical disability, subjective pain levels, and healthcare utilization at 1, 3, and 5 years post-diagnosis, after controlling for baseline disease activity and joint damage. Patients reporting higher initial anxiety and lower social support satisfaction demonstrated significantly poorer adaptation and accelerated functional decline over subsequent years.
Reliability
The IRGL has undergone rigorous reliability testing in diverse patient populations across clinical and research settings in Western Europe.
Internal Consistency
Internal consistency has been repeatedly substantiated through the calculation of Cronbach’s alpha ($\alpha$) coefficients across independent validation samples. In the foundational standardization cohort of 244 rheumatoid arthritis patients reported by Huiskes et al. (1990):
- Mobility: $\alpha = .82$ to $.87$
- Self-Care: $\alpha = .78$ to $.84$
- Dexterity: $\alpha = .81$ to $.86$
- Anxiety: $\alpha = .86$ to $.91$
- Depressed Mood: $\alpha = .84$ to $.89$
- Positive Affect: $\alpha = .80$ to $.85$
- Social Support Received: $\alpha = .79$ to $.85$
- Social Support Satisfaction: $\alpha = .83$ to $.88$
- Pain: $\alpha = .85$ to $.90$
Subsequent empirical investigations (e.g., Evers et al., 2003) utilizing large patient samples ($N > 400$) reaffirmed these findings, with all core dimensions consistently meeting or exceeding the recommended psychometric threshold of $.70$ for group comparisons, and several key subscales exceeding $.85$, rendering them sufficiently reliable for individual diagnostic tracking.
Test-Retest Reliability
Test-retest stability was investigated across stable clinical intervals spanning 2 to 4 weeks among patients with medically stable rheumatoid arthritis. Intraclass correlation coefficients (ICCs) and Pearson correlation coefficients ranged from $.74$ to $.91$ across all subscales. The physical functioning and social network structural indices demonstrated the highest temporal stability ($r > .85$), whereas the anxiety and pain subscales showed moderate fluctuations ($r = .72$ to $.80$), appropriately capturing natural episodic symptom variation while maintaining strong underlying trait stability.
Factor Analysis
The structural dimensionality of the IRGL was established using both exploratory factor analysis (EFA) during its initial scale construction and confirmed via confirmatory factor analysis (CFA) in subsequent clinical populations.
Exploratory Factor Structure
Huiskes, Kraaimaat, and Bijlsma (1990) conducted principal component analyses (PCA) with oblimin (oblique) and varimax (orthogonal) rotations on item clusters derived from the Dutch adaptation of the AIMS alongside newly formulated items. The analysis consistently yielded clear, interpretable factor solutions reflecting distinct, lower-order functional dimensions rather than a single undifferentiated "illness severity" dimension:
- Physical Sub-dimensions: Factor loadings for items representing Mobility, Self-Care, and Dexterity loaded cleanly onto three distinct physical factors, with primary item loadings consistently exceeding $.55$ and minimal cross-loadings ($< .25$).
- Psychological Sub-dimensions: Items assessing emotional state partitioned clearly into two opposing affective dimensions: negative affectivity (which further segregated into Anxiety and Depressed Mood factors) and positive affectivity (Positive Affect factor), loading with absolute values between $.60$ and $.84$.
- Social Support Dimensions: Factor analysis of the interpersonal items confirmed the statistical separation between structural support (network size), functional support received, and emotional satisfaction with support.
Confirmatory Factor Analysis and Model Fit
Subsequent psychometric evaluations utilizing structural equation modeling (SEM) confirmed that a hierarchical, multi-factor model provides a significantly superior fit compared to unidimensional or simple three-factor (physical, psychological, social) models. When modeling a higher-order structure with physical, psychological, and social second-order factors subsuming their respective primary subscales, fit indices met standard criteria for adequate model fit:
- Root Mean Square Error of Approximation (RMSEA) $le .058$
- Comparative Fit Index (CFI) $ge .93$
- Tucker-Lewis Index (TLI) $ge .92$
- Standardized Root Mean Square Residual (SRMR) $le .062$
These findings substantiate that while the subscales correlate within broad domains (e.g., Mobility and Self-Care sharing significant covariance), each subscale captures sufficient unique variance to warrant independent reporting and profile analysis.
Instrument / Measurement Tool
The IRGL is structured as a comprehensive, standardized, pencil-and-paper or digital self-administered questionnaire. Its structural parameters are outlined below:
- Complete Instrument Name: Influence of Rheumatism on Health and Lifestyle (Invloed van Reuma op Gezondheid en Leefwijze; IRGL)
- Original Authors: C. J. E. A. Huiskes, Floris W. Kraaimaat, and Johannes W. J. Bijlsma
- Year of Publication: 1990
- Target Population: Adults ($ge 18$ years) and older adults diagnosed with chronic inflammatory or degenerative rheumatic conditions (e.g., rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, systemic lupus erythematosus, fibromyalgia).
- Administration Format: Self-report questionnaire completed independently by the patient; interviewer-administered administration is permissible for individuals with severe visual or upper-limb functional impairments.
- Total Item Inventory: 68 items grouped into 16 thematic question clusters.
- Completion Time: Approximately 15 to 25 minutes depending on patient fatigue and hand joint impairment.
- Recall Reference Periods:
- Physical functioning scales: Prior month (last 4 weeks).
- Psychological functioning scales: Prior week (affective states) and prior month (general psychological well-being).
- Social functioning scales: Prior six months.
- Response Formats: Categorical Likert-type scales tailored to subscale context:
- 4-point Likert scales (e.g., 1 = without difficulty, 2 = with some difficulty, 3 = with much difficulty, 4 = unable to do).
- 5-point frequency scales (e.g., 1 = almost never, 2 = seldom, 3 = sometimes, 4 = often, 5 = almost always).
- 5-point intensity and satisfaction scales (e.g., 1 = very dissatisfied to 5 = very satisfied).
- Scoring and Transformation Rules:
- Negatively keyed items are reverse-coded prior to subscale aggregation.
- Raw scores for each subscale are calculated by summing the corresponding item scores.
- Raw scores are typically linearly converted to a standardized 0–100 scale, where either higher scores uniformly reflect better health/functioning or, alternatively, higher scores reflect greater impairment (depending on whether the clinician adopts the disability-oriented or health-oriented scoring manual). In standard clinical practice, physical scales are scored such that higher values denote greater disability, whereas positive affect and social support satisfaction are scored such that higher values denote greater resources.
- A global composite score is discouraged; profile reporting across the distinct subscales is recommended.
Permissions & Fee and Test Year
The IRGL was originally published in 1990 by C. J. E. A. Huiskes, F. W. Kraaimaat, and J. W. J. Bijlsma in the Netherlands. The questionnaire, test manual, and scoring forms were distributed through academic and medical research channels, specifically affiliated with Utrecht University (Department of Clinical Psychology) and the University Medical Center Utrecht (Department of Rheumatology and Clinical Immunology).
The instrument, scoring instructions, and accompanying clinical guidelines are protected under academic copyright. However, for non-commercial academic research, epidemiologic investigations, and routine non-profit clinical practice, the IRGL is generally accessible upon request or through documented use in peer-reviewed scientific literature. Researchers and clinicians wishing to employ the IRGL in prospective clinical trials, commercial evaluations, or digital platforms must consult the copyright holders or academic successors at Utrecht University or Radboud University Nijmegen to secure formal permission and ensure use of the official, validated Dutch scoring algorithms.
References
Below are primary foundational references and key peer-reviewed empirical studies documenting the psychometric development, validation, and clinical application of the IRGL:
- Evers, A. W. M., Kraaimaat, F. W., Geenen, R., & Bijlsma, J. W. J. (1998). Determinants of psychological distress and its stability in patients with recent-onset rheumatoid arthritis: A prospective study. Journal of Psychosomatic Research, 45(5), 415–426. https://doi.org/10.1016/S0022-3999(98)00021-3
- Evers, A. W. M., Kraaimaat, F. W., Geenen, R., Jacobs, J. W. G., & Bijlsma, J. W. J. (2003). Pain coping and social support as predictors of long-term functional disability and pain in early rheumatoid arthritis. Behaviour Research and Therapy, 41(11), 1295–1310. https://doi.org/10.1016/S0005-7967(03)00036-6
- Huiskes, C. J. E. A., Kraaimaat, F. W., & Bijlsma, J. W. J. (1990). Handleiding Invloed van Reuma op Gezondheid en Leefwijze (IRGL) [Manual: Influence of Rheumatism on Health and Lifestyle]. Vakgroep Klinische Psychologie, Universiteit Utrecht & Afdeling Reumatologie, Academisch Ziekenhuis Utrecht.
- Huiskes, C. J. E. A., Kraaimaat, F. W., & Bijlsma, J. W. J. (1990). De ontwikkeling van een zelfbeoordelingslijst voor het meten van de gezondheidstoestand van patiënten met reuma: De IRGL [Development of a self-assessment scale for measuring the health status of patients with rheumatism: The IRGL]. Gedrag & Gezondheid, 18(3), 137–146.
- Meenan, R. F., Gertman, P. M., & Mason, J. H. (1980). Measuring health status in arthritis: The Arthritis Impact Measurement Scales. Arthritis & Rheumatism, 23(2), 146–152. https://doi.org/10.1002/art.1780230203
- van Lankveld, W., van't Pad Bosch, P., van de Putte, L., Näring, G., & van der Staak, C. (1994). Disease-specific stressors in rheumatoid arthritis: Coping and well-being. British Journal of Rheumatology, 33(11), 1067–1073. https://doi.org/10.1093/rheumatology/33.11.1067