Department of Epidemiology.
Department of Medicine.
Rheumatology (Oxford). 2021 Dec 1;60(12):5713-5723. doi: 10.1093/rheumatology/keab236.
Idiopathic inflammatory myopathies (IIMs) cause proximal muscle weakness, which affects the ability to carry out the activities of daily living. Wearable physical activity monitors (PAMs) objectively assess continuous activity and potentially have clinical usefulness in the assessment of IIMs. We examined the psychometric characteristics for PAM outcomes in IIMs.
Adult IIM patients were prospectively evaluated (at baseline, 3 months and 6 months) in an observational study. A waist-worn PAM (ActiGraph GT3X-BT) assessed average step counts/minute, peak 1-minute cadence, and vector magnitude/minute. Validated myositis core set measures (CSMs) including manual muscle testing (MMT), physician global disease activity (MD global), patient global disease activity (Pt global), extramuscular disease activity (Ex-muscular global), HAQ-DI (HAQ disability index), muscle enzymes, and patient-reported physical function were evaluated. Test-retest reliability, construct validity, and responsiveness were determined for PAM measures and CSMs, using Pearson correlations and other appropriate analyses.
A total of 50 adult IIM patients enrolled [mean (s.d.) 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 to -0.48), Pt global (r=-0.43 to -0.61), HAQ-DI (r = -0.47 to -0.59) and MMT (r = 0.37-0.52), and strong discriminant validity for categorical MMT and HAQ-DI. Longitudinal associations with MD global (r=-0.38 to -0.44), MMT (r = 0.50-0.57), HAQ-DI (r = -0.45 to -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-minute cadence had the largest effect size and standardized response means.
PAM measures showed promising construct validity, reliability, and longitudinal responsiveness; especially peak 1-minute cadence. PAMs are able to provide valid outcome measures for future use in IIM clinical trials.
特发性炎性肌病（IIM）可导致近端肌肉无力，从而影响日常生活活动能力。可穿戴式身体活动监测器（PAM）可客观评估连续活动，并且在评估 IIM 方面具有潜在的临床意义。我们检查了 PAM 结果在 IIM 中的心理测量特性。
在一项观察性研究中，前瞻性评估了成年 IIM 患者（基线、3 个月和 6 个月时）。佩戴在腰部的 PAM（ActiGraph GT3X-BT）评估平均每分钟步数、最高 1 分钟步频和矢量幅度/分钟。评估了经过验证的肌炎核心组测量指标（CSMs），包括手动肌肉测试（MMT）、医生整体疾病活动度（MD global）、患者整体疾病活动度（Pt global）、肌肉外疾病活动度（Ex-muscular global）、HAQ-DI（残疾指数）、肌肉酶和患者报告的身体功能。使用 Pearson 相关和其他适当的分析方法，确定了 PAM 测量指标和 CSMs 的测试-重测信度、结构效度和反应度。
共纳入 50 名成年 IIM 患者[平均（标准差）年龄，53.6（14.6）；60%女性，94%白种人]。PAM 测量值具有很强的测试-重测信度，在基线时与 MD global（r=-0.37 至-0.48）、Pt global（r=-0.43 至-0.61）、HAQ-DI（r=-0.47 至-0.59）和 MMT（r=0.37-0.52）具有中度至强相关性，对 MMT 和 HAQ-DI 的分类具有很强的判别效度。与 MD global（r=-0.38 至-0.44）、MMT（r=0.50-0.57）、HAQ-DI（r=-0.45 至-0.55）和功能测试（r=0.30-0.65）的纵向关联为中度至强。PAM 测量值对 MMT 改善≥10%和 ACR/EULAR 肌炎反应标准的中度至主要改善具有反应性。最高 1 分钟步频的效应量和标准化反应均值最大。
PAM 测量值具有良好的结构效度、可靠性和纵向反应性；特别是最高 1 分钟步频。PAM 能够提供有效的结局测量指标，未来可用于 IIM 临床试验。
