Collaborative research in myositis-related disorders: MIHRA, a global shared community model.

Myositis International Health and Research Collaborative Alliance (MIHRA) is a newly formed purpose-built non-profit charitable research organization dedicated to accelerating international clinical trial readiness, global professional and lay education, career development and rare disease advocacy in IIM-related disorders. In its long form, the name expresses the community's scope of engagement and intent. In its abbreviation, MIHRA, conveys linguistic roots across many languages, that reflects the IIM community's spirit with meanings such as kindness, community, goodness, and peace. MIHRA unites the global multi-disciplinary community of adult and pediatric healthcare professionals, researchers, patient advisors and networks focused on conducting research in and providing care for pediatric and adult IIM-related disorders to ultimately find a cure. MIHRA serves as a resourced platform for collaborative efforts in investigator-initiated projects, consensus guidelines for IIM assessment and treatment, and IIM-specific career development through connecting research networks.MIHRA's infrastructure, mission, programming and operations are designed to address challenges unique to rare disease communities and aspires to contribute toward transformative models of rare disease research such as global expansion and inclusivity, utilization of community resources, streamlining ethics and data-sharing policies to facilitate collaborative research. Herein, summarises MIHRA operational cores, missions, vision, programming and provision of community resources to sustain, accelerate and grow global collaborative research in myositis-related disorders.

Mental health in paediatric and adult myositis-related diseases: current state of research, interventions, and future steps from the MIHRA Psychological Impact Scientific Working Group.

Psychological and emotional well-being are critical aspects of overall health for individuals with chronic rheumatologic conditions. Mental health-related literature, however, predominantly focuses on systemic lupus erythematosus or rheumatoid arthritis, with limited emphasis on idiopathic inflammatory myopathies (IIMs). High proportions of those with juvenile myositis report psychological distress at levels warranting mental health referral. Adults with dermatomyositis diagnosed with depression or anxiety do not receive adequate mental health care. Mental health symptoms in those with IIMs are associated with worse health-related quality of life, medication adherence, and disease outcomes. Despite demonstrated high rates of mental health burden, access to mental health care remains severely lacking.Data related to mental health burden is limited by small sample size, limited generalisability, variable methods of assessment, and inconsistent diagnosis codes to define mental health conditions. Additional research is needed to validate current screening tools in myositis populations. Other relevant measurable factors include disease severity, non-health- and health-related trauma exposure, loneliness, isolation, loss of control, sleep difficulties, fatigue, pain, self-esteem, body image, sexual health, and health inequities. Studiesare needed investigating the efficacy of therapeutic and pharmacologic interventions among patients with myositis who experience depression and anxiety. Currently, knowledge and resources are limited around mental health burden and potential intervention for those living with IIMs. The Myositis International Health & Research Collaborative Alliance (MIHRA) Psychological Impact Scientific Working Group offers a preliminary road map to characterise and prioritise the work ahead to understand baseline mental health burden and compare avenues for intervention.

Obesity is associated with pain and impaired mobility despite therapy in systemic lupus erythematosus.

Objective: To investigate whether abnormal BMI is associated with health-related quality of life (HRQoL) impairments, defined as patient-reported problems within the different dimensions of the three-level EQ-5D (EQ-5D-3L), before and after treatment for active systemic lupus erythematosus (SLE). Patients and methods: We conducted a post-hoc analysis of data from two phase III clinical trials of belimumab in SLE, i.e., BLISS-52 (n = 865) and BLISS-76 (n = 819). Underweight was defined as BMI <18.5 kg/m2, normal weight as BMI ≥18.5 but <25 kg/m2, pre-obesity as BMI ≥25 but <30 kg/m2, and obesity as BMI ≥30 kg/m2. We investigated associations between BMI groups and problems (level 2 or 3) within each one of the five EQ-5D dimensions before treatment initiation and at week 52, using logistic regression analysis adjusting for age, ethnicity, disease activity, and glucocorticoid dose, and for the post-treatment analysis also for belimumab treatment and baseline EQ-5D-3L responses. Results: Of 1,684 patients included, 73 (4%) were classified as underweight, 850 (50%) as normal weight, 438 (26%) as pre-obese, and 323 (19%) as obese. At baseline, obesity was associated with mild to severe problems in all EQ-5D dimensions (p < 0.05 for all), yielding the strongest association with problems in mobility (adjusted odds ratio, aOR: 2.1; 95% confidence interval, CI: 1.6-2.8; p < 0.001). Pre-obesity was also associated with problems in mobility (aOR: 1.4; 95% CI: 1.1-1.8; p = 0.005). Post-intervention, obesity was associated with problems in mobility and pain/discomfort, and pre-obesity with problems in mobility and self-care (p < 0.05 for all). Conclusion: Our study adds to the evidence that high BMI negatively affects SLE patients' HRQoL, with obesity being associated with pain and impaired mobility despite therapy.

Sensitivity analysis of EQ-5D-3L index scores in terms of discriminative and known-groups validity in SLE: introducing Adequate Health State.

OBJECTIVES: To investigate the ability of different EuroQol 5-Dimensions 3-Levels (EQ-5D-3L) index scores to discriminate between verum drug and placebo (discriminant validity) as well as between responders and non-responders (known-groups validity) in the SLE patient population of two phase III clinical trials of belimumab. METHODS: Data from the BLISS-52 (NCT00424476) and BLISS-76 (NCT00410384) trials (N = 1684), which both showed superiority of belimumab to placebo, were utilized. Responders were defined as SLE Responder Index 4 (SRI-4) achievers at week 52. The Pearson's χ2 and Mann-Whitney U tests were used for comparisons, and logistic regression analysis was used for adjustments for confounders and assessment of independence. RESULTS: While full health state (FHS; EQ-5D index score 1) showed the best ability to discriminate between belimumab and placebo [adjusted odds ratio (OR) 1.47; 95% CI 1.11, 1.96; P = 0.008] and between SRI-4 responders and non-responders (adjusted OR 3.47; 95% CI 1.29, 10.98; P = 0.020), the discriminative ability of EQ-5D index scores 0.800 or more reached statistical significance for both discriminant validity (adjusted OR 1.29; 95% CI 1.02, 1.63; P = 0.036) and known-groups validity (adjusted OR 3.08; 95% CI 1.16, 9.69; P = 0.034). CONCLUSION: Overall, higher EQ-5D index scores were associated with increasing ability to discriminate between belimumab and placebo, and between responders and non-responders. EQ-5D index scores less stringent than FHS may be clinically relevant health-related quality of life goals of treatment in patients with SLE, introducing the concept of EQ-5D adequate health state when FHS is not achievable.

Reliability and validity of PROMIS physical function, pain interference, and fatigue as patient reported outcome measures in adult idiopathic inflammatory myopathies: International study from the OMERACT myositis working group.

OBJECTIVE: Pain interference, fatigue, and impaired physical function are common features of idiopathic inflammatory myopathies (IIM). The objective of this study was to evaluate the construct validity and test-retest reliability of the Patient Reported Outcome Information System (PROMIS) Pain Interference 6av1.0, Fatigue 7av1.0, and Physical Function 8bv2.0 instruments. METHODS: Patient-Reported Outcome Measures (PROMs) were deployed to adult IIM patients from OMERACT Myositis Working Group (MWG) international clinic sites via two online surveys (2019, 2021). Internal consistency of each PROM was analyzed by Cronbach's α. Construct validity was determined by a priori hypotheses generated by the MWG with >75% agreement for each hypothesis and calculated with Pearson correlations. Test-retest reliability was assessed using intraclass correlation coefficient with PROMIS instruments administered at time zero and 7 days. RESULTS: Surveys were sent to 368 participants in total; participants who completed each questionnaire varied (n=65 to 263). For construct validity, 10 out of 13 a priori hypotheses were met supporting construct validity of PROMIS instruments (Pain Interference 3/4, fatigue 4/4, and Physical Function 3/5). Test-retest reliability was strong for all PROMIS instruments. All PROMIS instruments demonstrated excellent internal consistency. None of the measures demonstrated any ceiling or floor effects except for a ceiling effect in the Pain Interference instrument. CONCLUSIONS: This study presents test-retest reliability and construct validity evidence supporting PROMIS Pain Interference (6a v1.0), Fatigue (7a v1.0), and Physical Function (8b v2.0) using a large international cohort of patients with IIM. Internal consistency of these instruments was excellent. A ceiling effect was noted in the Pain Interference instrument.

Experiences of participation in activities among girls with juvenile idiopathic arthritis: A qualitative study.

This study aimed to describe how girls with juvenile idiopathic arthritis (JIA) experience participation in activities in relation to their disease. Semi-structured interviews of eight girls with JIA in ages 12-15 were recorded and transcribed as a whole. Data have been analysed with qualitative content analysis. Participation was influenced by disease symptoms, which could result in absence and exclusion from participation in activities. The experience of participation was affected by the participant's choice of using strategies and making adjustments during activities. Social environment could both increase and decrease participation through treatment and type of knowledge about the disease. Also the physical environment could affect participation due to the climate or road and ground conditions. We could conclude that the experience of participation among girls with JIA was affected by disease symptoms, perceptions of selves, disease and the use of strategies, and also the social and physical environment. This indicates the need to address participation in clinical practice and the importance to include different health professionals, teachers and other personnel involved in the child's schooling.

The "Managing Fatigue" programme - Experiences shared by MS participants.

BACKGROUND: The "Managing Fatigue" (MF) programme can help people living with Multiple sclerosis (MS) manage fatigue in their everyday lives. The programme has been proven feasible with Swedish occupational therapists, but there is a lack of knowledge of how MS participants experience the programme, and what they learned from participating in the programme. AIM: To describe how Swedish MS participants experience the content and structure of the Swedish MF programme, as well as what they learned from participating in the programme. MATERIAL AND METHODS: Qualitative interviews were performed with nine MS participants, and data were analysed according to direct content analysis. RESULTS: Participants experienced programme material was relevant, and they valued the structured sessions that utilised different teaching forms. Participants described the group format and the experienced course leader nurtured their learning process. They learned occupational skills to save energy, to re-value daily occupations, and initiated a process of change, but individual support is needed after programme completion. CONCLUSION AND SIGNIFICANCE: Findings support programme feasibility among MS participants, and show the importance of being able to practice skills to handle fatigue in everyday life. Future studies should consider adding outcome measures focussing on engagement in occupations when evaluating programme effectiveness.

World Health Organization (WHO) International Classification of Functioning, Disability and Health (ICF) Core Set Development for Interstitial Lung Disease.

Background: The World Health Organization (WHO) introduced the International Classification of Functioning, Disability, and Health (ICF) as a scientific method of disability data collection comprised of >1,200 categories describing the spectrum of impairment types (functional, symptoms-based and anatomical) under the bio-psycho-social model with consideration of environmental and personal factors (pf). ICF Core Sets and ICF Checklists are streamlined disease-specific resources for clinical use, service provision, and for use in health economics and health policy. ICF can disclose strengths and weaknesses across multiple patient-reported outcome measures (PROMs) and help consolidate best-fitting question-items from multiple PROMs. Interstitial lung diseases (ILDs), are generally progressive, with restrictive physiology sometimes occurring in the context of multi-organ autoimmunity/inflammatory conditions such as connective tissue diseases (CTDs). In spite of significant associated morbidity and potential disability, ILD has yet to be linked to the ICF. Methods: Each instrument and their question-items within the consensus-recommended core sets for clinical trials in ILD were deconstructed to single concept units, and then linked per updated ICF linkage rules. Inter-linker agreement was established. Three additional subsequently validated measures were also included. Results: One-hundred-eleven ICF categories were identified for ten PROMs and three traditional objective measures that were amenable to ICF linkage. The proportion of agreement ranged from 0.79 (95% CI: 0.62, 0.91) to 0.93 (0.76, 0.99) with the overall proportion of inter-linker agreement being very high 0.86 (0.82, 0.89) for the initial instruments, with 94-100% for the three additional PROMs. Thirty-four new 'Personal Factors' emerged to capture disease-specific qualities not elsewhere described in ICF, e.g. 'pf_embarrassed by cough' or 'pf_panic/afraid when can't get a breath'. Conclusion: This first known effort in ICF linkage of ILD has provided important revelations on the current utility of the ICF in lung disease. Results have indicated areas for meaningful assessment of ICF descriptors for lung impairment. The mapping across PROMs provides insight into possibilities of developing more streamline and precise instrumentation. Finally, familiarity with the ICF in ILD may enable clinicians to experience a smoother transition with the imminent harmonization of ICD and ICF, ICD-11.

EQ-5D full health state after therapy heralds reduced hazard to accrue subsequent organ damage in systemic lupus erythematosus.

Objectives: To investigate whether self-reported EQ-5D full health state (FHS) after therapeutic intervention for active systemic lupus erythematosus (SLE) is associated with a reduced risk to accrue organ damage. In a separate analysis, we sought to investigate associations between experience of "no problems" in each one of the five dimensions of EQ-5D and the risk to accrue damage. Methods: Data from the open-label extension periods of the BLISS-52 and BLISS-76 trials of belimumab in SLE (NCT00724867; NCT00712933) were used (N = 973). FHS was defined as an experience of "no problems" in all five EQ-5D dimensions. Organ damage was assessed annually using the Systemic Lupus International Collaborating Clinics (SLICC)/American College of Rheumatology (ACR) Damage Index (SDI). Associations between the three-level version of the EQ-5D (EQ-5D-3L) responses at open-label baseline and the first documented increase in organ damage were investigated using Cox regression accounting for age, sex, ancestry, SDI at baseline, and background therapy, and associations with SDI items were investigated using phi (φ) correlation analyses. Results: A total of 147 patients (15.1%) accrued organ damage during follow-up, with the first increase in their SDI score occurring after a mean time of 29.1 ± 19.6 months. Lower proportions of FHS respondents accrued damage over a course of up to 7.9 years of open-label follow-up compared with no FHS respondents (p = 0.004; derived from the logrank test). FHS was associated with a reduced hazard to accrue subsequent organ damage (HR: 0.60; 95% CI: 0.38-0.96; p = 0.033) after adjustments, as was experience of "no problems" in mobility (HR: 0.61; 95% CI: 0.43-0.87; p = 0.006). "No problems" in mobility was negatively correlated with musculoskeletal damage accrual (φ = -0.08; p = 0.008) and associated with a lower hazard to accrue musculoskeletal damage in Cox regression analysis (HR: 0.38; 95% CI: 0.19-0.76; p = 0.006). Conclusion: Experience of EQ-5D-3L FHS and "no problems" in mobility after therapeutic intervention heralded reduced hazard to accrue subsequent organ damage, especially musculoskeletal damage, suggesting that optimisation of these health-related quality of life aspects constitutes a clinically relevant treatment target in patients with SLE, along with clinical and laboratory parameters.

Inflammatory Arthritis and the Effect of Physical Activity on Quality of Life and Self-Reported Function: A Systematic Review and Meta-Analysis.

OBJECTIVE: Although physical activity is an evidence-based intervention that reduces disease-related symptoms and comorbidity in rheumatoid arthritis (RA), the effect of physical activity on self-reported function and quality of life (QoL) has not yet been analyzed. The present study synthesizes the evidence for the effectiveness of physical activity on QoL and self-reported function in adults with RA, spondyloarthritis (SpA), and psoriatic arthritis (PsA). METHODS: The databases PubMed, Embase, CINAHL, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched to identify relevant randomized controlled trials (RCTs). Screening, risk of bias assessment (using the RoB 2.0 tool), and data extraction were independently performed by 2 or more of the authors. Meta-analyses were conducted with a random-effects model. RESULTS: Systematic review included 55 RCTs, and meta-analysis included 37 RCTs. Of the 55 studies included, 76%, 20%, and 4% were designed to investigate RA, SpA, and PsA, respectively. In the RA studies, effects of physical activity on QoL and function were found compared to the group of inactive controls; no effects were found compared to the group of active controls. In the SpA studies, the effects of physical activity on QoL were in favor of the control group. Effects of physical activity on function were found compared to the group of inactive controls and sustained in fatigue and pain when compared to the group of active controls. In the PsA studies, no effects on QoL were found, but effects on function were noted when compared to the group of inactive controls. The effect size was below 0.30 in the majority of the comparisons. CONCLUSION: Physical activity may improve QoL and self-reported function in individuals with RA, SpA, and PsA. However, larger trials are needed, especially in SpA and PsA.

Distribution and trajectory of direct and indirect costs of idiopathic inflammatory myopathies.

OBJECTIVES: To estimate the annual direct and indirect costs associated with Idiopathic Inflammatory Myopathies (IIM) over time, including the pre-diagnostic period. METHODS: A cohort of incident adult IIM patients (n = 673) was identified from the Swedish National Patient Register from 2010 to 2016 and matched with general population comparators (n = 3343). Follow-up started at IIM diagnosis and corresponding date in the general population. International Classification of Diseases codes (ICD-10) were used for IIM case definition. Costs were calculated using national register data. RESULTS: The costs related to IIM started to increase 2 years before diagnosis. In the year following diagnosis, the mean annual IIM cost was €21 639 compared to €4816 in the general population. Five years after diagnosis, the mean annual cost in the IIM cohort was €12 796. Outpatient visits, hospitalizations and productivity loss were the components driving the increment in overall annual disease-related expenditures. Indirect costs accounted for a significant portion of IIM long-term societal costs. The highest costs were found in individuals of working age with cancer-associated IIM. CONCLUSIONS: The mean annual costs in IIM were 3 to 5 times higher than in the general population in the 5-year period following diagnosis. These costs started to increase long before diagnosis, were at their peak in the year post-diagnosis and remained elevated thereafter. Indirect costs contributed to a substantial portion of this increment. Early in the IIM disease course, clinicians and allied health professionals should aim to improve function, reduce damage and address barriers to return-to-work to mitigate these costs.

Exercise as a multi-modal disease-modifying medicine in systemic sclerosis: An introduction by The Global Fellowship on Rehabilitation and Exercise in Systemic Sclerosis (G-FoRSS).

Systemic sclerosis (SSc) is a heterogeneous multisystem autoimmune disease whereby its main pathological drivers of disability and damage are vascular injury, inflammatory cell infiltration, and fibrosis. These mechanisms result in diffuse and diverse impairments arising from ischemic circulatory dysfunction leading to painful skin ulceration and calcinosis, neurovascular aberrations hindering gastrointestinal (GI) motility, progressive painful, incapacitating or immobilizing effects of inflammatory and fibrotic effects on the lungs, skin, articular and periarticular structures, and muscle. SSc-related impairments impede routine activities of daily living (ADLs) and disrupt three critical life areas: work, family, social/leisure, and also impact on psychological well-being. Physical activity and exercise are globally recommended; however, for connective tissue diseases, this guidance carries greater impact on inflammatory disease manifestations, recovery, and cardiovascular health. Exercise, through myogenic and vascular phenomena, naturally targets key pathogenic drivers by downregulating multiple inflammatory and fibrotic pathways in serum and tissue, while increasing circulation and vascular repair. G-FoRSS, The Global Fellowship on Rehabilitation and Exercise in Systemic Sclerosis recognizes the scientific basis of and advocates for education and research of exercise as a systemic and targeted SSc disease-modifying treatment. An overview of biophysiological mechanisms of physical activity and exercise are herein imparted for patients, clinicians, and researchers, and applied to SSc disease mechanisms, manifestations, and impairment. A preliminary guidance on exercise in SSc, a research agenda, and the current state of research and outcome measures are set forth.

EQ-5D-3L full health state discriminates between drug and placebo in clinical trials of systemic lupus erythematosus.

OBJECTIVES: The objectives of this study were to investigate the discriminative ability of EQ-5D-3L full health state (FHS) in clinical trials of SLE, and to identify factors associated with FHS after treatment. METHODS: Data from the BLISS-52 (NCT00424476) and BLISS-76 (NCT00410384) trials of belimumab (N = 1684) were utilized. FHS was defined as a response of no problems in all five EQ-5D-3L dimensions, yielding an index score of 1. The Pearson's χ2 or Fisher's exact test was employed for comparisons, and logistic regression for adjustments and assessment of independence. RESULTS: We demonstrated higher EQ-5D-3L FHS frequencies among patients given standard therapy (ST) plus the licensed belimumab dose vs ST alone (26.1% vs 19.4%; P = 0.001; week 52), and within SRI-4 responders vs non-responders (27.0% vs 19.8%; P < 0.001; week 52) from weeks 36 to 52. In multivariable regression analysis, SLEDAI-2K (OR: 0.90; 95% CI: 0.87, 0.94; P < 0.001) and SLICC/ACR Damage Index (OR: 0.79; 95% CI: 0.69, 0.91; P = 0.001) scores were independently associated with lower FHS frequencies at week 52, while adding monthly infusions of belimumab 10 mg/kg to ST favoured FHS perception (OR: 1.60; 95% CI: 1.15, 2.24; P = 0.006). Add-on belimumab 10 mg/kg yielded higher FHS frequencies in antimalarial users vs non-users (29.9% vs 20.1%; P = 0.011), and in anti-dsDNA- and anti-Sm- positive vs negative patients (31.4% vs 13.4%; P < 0.001 and 33.0% vs 22.6%; P = 0.010, respectively), whereas no significant differences were observed in patients given ST alone. CONCLUSION: EQ-5D-3L FHS distinguished belimumab from placebo and responders from non-responders, and exhibited known-group validity in subgroup analysis. FHS may prove a useful patient-reported outcome in SLE studies.

Assessing the content validity of patient-reported outcome measures in adult myositis: A report from the OMERACT myositis working group.

OBJECTIVE: To investigate the content validity of several patient-reported outcome measures (PROMs) in patients with idiopathic inflammatory myopathies (IIM). METHODS: Seven individual PROM instruments were selected by the Outcome Measures in Rheumatology (OMERACT) Myositis Working Group relating to the following domains: pain, fatigue, physical function and physical activity. Twenty patients from the Johns Hopkins Myositis Center were selected for one-on-one face-to-face or phone interviews for cognitive interviewing of individual PROMs to assess comprehension and content validity. Additionally, patients were asked if they thought muscle symptoms, an area originally identified in qualitative studies, were encapsulated by the other four domains. RESULTS: The majority of patients (>70%) felt that each of the instruments was clear, easy to read and understand, and could be used for assessment of its domain. Two-thirds (66%) of patients felt that 'muscle symptoms' were captured by the other domains. CONCLUSIONS: We provided evidence to support adequate content validity for several PROMs. Further research is needed to determine whether 'muscle symptoms' warrant a separate domain.

OMERACT 2018 Modified Patient-reported Outcome Domain Core Set in the Life Impact Area for Adult Idiopathic Inflammatory Myopathies.

OBJECTIVE: To present and vote on a myositis modified patient-reported outcome core domain set in the life impact area at the Outcome Measures in Rheumatology (OMERACT) 2018. METHODS: Based on results from international focus groups and Delphi surveys, a draft core set was developed. RESULTS: Domains muscle symptoms, fatigue, level of physical activity, and pain reached ≥ 70% consensus and were mandatory to assess in all trials. Domains lung, joint, and skin symptoms were mandatory in specific circumstances. This core set was endorsed by > 85% at OMERACT 2018. CONCLUSION: We propose a life impact core set for patients with idiopathic inflammatory myopathies and will proceed with instrument selections.

Perceptions of Patients, Caregivers, and Healthcare Providers of Idiopathic Inflammatory Myopathies: An International OMERACT Study.

OBJECTIVE: Patient-reported outcome measures (PROM) that incorporate the patient perspective have not been well established in idiopathic inflammatory myopathies (IIM). As part of our goal to develop IIM-specific PROM, the Outcome Measures in Rheumatology (OMERACT) Myositis special interest group sought to determine which aspects of disease and its effects are important to patients and healthcare providers (HCP). METHODS: Based on a prior qualitative content analysis of focus groups, an initial list of 24 candidate domains was constructed. We subsequently conducted an international survey to identify the importance of each of the 24 domains to be assessed in clinical research. Patients with IIM, their caregivers, and HCP treating IIM completed the survey. RESULTS: In this survey, a total of 638 respondents completed the survey, consisting of 510 patients, 101 HCP, and 27 caregivers from 48 countries. Overall, patients were more likely to rank "fatigue," "cognitive impact," and "difficulty sleeping" higher compared with HCP, who ranked "joint symptoms," "lung symptoms," and "dysphagia" higher. Both patients and providers rated muscle symptoms as their top domain. In general, patients from different countries were in agreement on which domains were most important. One notable exception was that patients from Sweden and the Netherlands ranked lung symptoms significantly higher compared to other countries including the United States and Australia (mean weighted rankings of 2.86 and 2.04 vs 0.76 and 0.80, respectively; p < 0.0001). CONCLUSION: Substantial differences exist in how IIM is perceived by patients compared to HCP, with different domains prioritized. In contrast, patients' ratings across the world were largely similar.

Muscle Strength and Muscle Endurance During the First Year of Treatment of Polymyositis and Dermatomyositis: A Prospective Study.

OBJECTIVE: To investigate muscle impairment (isometric and dynamic) and disease activity during the first year after diagnosis of polymyositis (PM) and dermatomyositis (DM), and to study the relationship between muscle impairment, patient-reported health, and disease activity. METHODS: Seventy-two patients enrolled in the Swedish Myositis Register, 2003-2010, were followed prospectively. The Manual Muscle test (MMT-8; isometric muscle strength), the Functional Index of myositis test (FI-2; dynamic, repetitive muscle function), and disease activity (6-item core set) were retrieved at the time of diagnosis, and after 6 and 12 months. Self-reported health (Medical Outcomes Study Short Form-36; SF-36) was retrieved at 12 months. RESULTS: At the time of diagnosis, median (Q1-Q3) for the FI-2 was 27.2% (7.9-60.5%) of maximal score compared to 93.8% (92.5-98.8%) of maximal MMT-8. At 12 months, the FI-2 and the MMT-8 improved to 29.4% (16.5-60.7%; p < 0.05) and 96.1% (88.1-99.4%), respectively (p < 0.01). At 12 months, 45% of patients improved ≥ 20%, and 27% worsened ≥ 20% in FI-2 score, while 10% improved ≥ 20% in MMT-8. Physician's global visual analog scale (VAS), Health Assessment Questionnaire, and creatine phosphokinase levels improved significantly at 12 months (p < 0.05-0.001) while patient's global and extramuscular VAS remained unchanged. The SF-36 physical function correlated strongly with the FI-2 (rs = 0.74; CI 0.55-0.85) and moderately with the MMT (rs = 0.54; CI 0.27-0.73), with lower correlations between muscle function and other SF-36 domains. CONCLUSION: Patients with PM/DM were characterized by impaired dynamic repetitive muscle function (DRMF) that correlated well with patient-reported physical function. Assessment of DRMF adds information regarding muscle impairment in these patients.