A Review of The Evidence for the Utility of Physical Activity Monitor Use in Patients with Idiopathic Inflammatory Myopathies

Few proven therapies exist for patients with idiopathic inflammatory myopathies (IIM), partly due to the lack of reliable and valid outcome measures for assessing treatment responses. The current core set measures developed by the International Myositis Assessment and Clinical Studies group were developed to standardize assessments of disease activity and treatment effect. None of the current measures address functional improvement in muscle weakness. Therefore, supplemental measures for more objectively assessing physical activity levels and fatiguability in free-living settings are needed to assess disease activity more comprehensively. Validated physical activity monitors (PAMs) have the potential to serve as an objective functional outcome measure in clinical trials and observational studies. This review examines the current evidence for using body-worn PAMs in clinical settings with IIM patients. A practical overview of methods for PAM use in clinical patient populations (including measurement details and data processing) that focuses on IIM patients is also presented.

Reliability, Validity and Responsiveness of Physical Activity Monitors in Patients with Inflammatory Myopathy

OBJECTIVE

Idiopathic inflammatory myopathies (IIM) cause proximal muscle weakness, which affect activities of daily living. Wearable physical activity monitors (PAMs) objectively assess continuous activity with potential clinical usefulness in IIM assessment. We examined the psychometric characteristics for PAM outcomes in IIM.

METHODS

Adult IIM patients were prospectively evaluated (baseline, 3 and 6-months) in an observational study. A waist-worn PAM (ActiGraph GT3X-BT) assessed average step counts/min, peak 1-min cadence, and vector magnitude/min. Validated myositis core set measures (CSM) including manual muscle testing (MMT), physician global disease activity (MD global), patient global disease activity (Pt global), extra-muscular disease activity (Ex-muscular global), HAQ-DI, muscle enzymes, and patient-reported physical function were evaluated. Test-retest reliability, construct validity, and responsiveness were determined for PAM measures and CSM using Pearson correlations and other appropriate analyses.

RESULTS

50 adult IIM patients enrolled [mean (SD) age, 53.6 (±14.6); 60% female, 94% Caucasian]. PAM measures showed strong test-retest reliability, moderate-to-strong correlations at baseline with MD global (r=-0.37- -0.48), Pt-global (r=-0.43- -0.61), HAQ-DI (r=-0.47- -0.59) and MMT (r = 0.37-0.52), and strong discriminant validity for categorical MMT and HAQ-DI. Longitudinal association with MD global (r=-0.38- -0.44), MMT (r = 0.50-0.57), HAQ-DI (r=-0.45- -0.55), and functional tests (r = 0.30-0.65) were moderate-to-strong. PAM measures were responsive to MMT improvement (≥10%) and moderate-to-major improvement on ACR/EULAR myositis response criteria. Peak 1-min cadence had the largest effect size and Standardized Response Means (SRMs).

CONCLUSION

PAM measures showed promising construct validity, reliability, and longitudinal responsiveness; especially peak 1-min cadence. PAMs provide valid outcome measures for future use in IIM clinical trials.

The clinical phenotype of Systemic Sclerosis patients with anti-PM/Scl antibodies: results from the EUSTAR cohort

OBJECTIVE

To evaluate clinical associations of anti-PM/Scl antibodies in patients with Systemic Sclerosis (SSc) in a multicentre international cohort, with particular focus on unresolved issues, including scleroderma renal crisis (SRC), malignancies, and functional outcome of interstitial lung disease (ILD).

METHODS

(1) Analysis of SSc patients from the EUSTAR database: 144 anti-PM/Scl+ without SSc-specific autoantibodies were compared to 7,202 anti-PM/Scl-, and then to 155 anti-Pm/Scl+ with SSc-specific antibodies. (2) Case-control study: additional data were collected for 165 anti-PM/Scl+ SSc (85 from the EUSTAR registry), and compared to 257 anti-PM/Scl- SSc controls, matched for sex, cutaneous subset, disease duration, and age at SSc onset.

RESULTS

Patients with isolated anti-PM/Scl positivity, as compared with anti-Pm/Scl-, had higher frequency of muscle involvement, ILD, calcinosis and cutaneous signs of dermatomyositis, but similar frequency of SRC and malignancies (either synchronous with SSc onset or not). The presence of muscle involvement was associated with a more severe disease phenotype. Although very frequent, ILD had a better functional outcome in cases than in controls.In patients with both anti-PM/Scl and SSc-specific antibodies, a higher frequency of typical SSc features than in those with isolated anti-PM/Scl was observed.

CONCLUSION

The analysis of the largest series of anti-PM/Scl+ SSc patients so far reported helps to delineate a specific clinical subset with muscle involvement, cutaneous dermatomyositis, calcinosis, and ILD characterized by a good functional outcome. SRC and malignancies do not seem to be part of this syndrome.

Influenza H1N1 virus-associated pneumonia often resembles rapidly progressive interstitial lung disease seen in collagen vascular diseases and COVID-19 pneumonia; CT-pathologic correlation in 24 patients

Purpose

To describe computed tomography (CT) findings of influenza H1N1 virus-associated pneumonia (IH1N1VAP), and to correlate CT findings to pathological ones.

Methods

The study included 24 patients with IH1N1VAP. Two observers independently evaluated the presence, distribution, and extent of CT findings. CT features were divided into either classical form (C-form) or non-classical form (NC-form). C-form included: A.) broncho-bronchiolitis and bronchopneumonia type, whereas NC-forms included: B.) diffuse peribronchovascular type, simulating subacute rheumatoid arthritis-associated (RA) interstitial lung disease (ILD) and C.) lower peripheral and/or peribronchovascular type, resembling dermatomyositis-associated ILD and COVID-19 pneumonia. In 10 cases with IH1N1VAP where lung biopsy was performed, CT and pathology findings were correlated.

Results

The most common CT findings were ground-glass opacities (24/24, 100 %) and airspace consolidation (23/24, 96 %). C-form was found in 11 (46 %) patients while NC-form in 13 (54 %). Types A, B, and C were seen in 11(46 %), 4 (17 %), and 9 (38 %) patients, respectively. The lung biopsy revealed organizing pneumonia in all patients and 6 patients (60 %) showed incorporated type organizing pneumonia that was common histological findings of rapidly progressive ILD.

Conclusion

In almost half of patients of IH1N1VAP, CT images show NC-form pneumonia pattern resembling either acute or subacute RA or dermatomyositis-associated ILD and COVID-19 pneumonia.