Pain is Common in Myositis and Associated with Disease Activity.

Abstract

Understanding pain in myositis remains challenging. This study aimed to assess patient-reported pain and its correlation with myositis core set measures (CSMs), patient-reported outcomes (PROs), and functional measures. Fifty subjects underwent baseline, 3-month, and 6-month assessments, evaluating myositis CSMs, functional measures, and patient-reported outcomes. Pain was measured using three methods: (1) a 10-cm Visual Analogue Scale (VAS), (2) pain score from the HAQ-DI, and (3) SF-36 (Short Form survey) pain questions. Correlations between disease activity measures and pain were examined at baseline, and changes in both were assessed at 6 months, along with longitudinal change of pain. The change in pain was also correlated with the published 2016 ACR/EULAR myositis response criteria, physician/patient's assessment of change. Nearly half of patients (45%) reported moderate to severe pain in all 3 pain scales, with higher severity of pain in PM/NM subset. At baseline, pain severity showed a strong correlation with most CSMs, PROs and functional outcomes in all the 3 pain scales and similar trends were noted for change in pain at the 6 months. On longitudinal analysis, the physical function scores and fatigue showed strong correlation with pain. Pain improved in myositis patients with improvement in disease activity over time. Pain is common in myositis and is associated with multiple measures of disease activity, PROs, and functional outcomes in myositis. Most importantly pain improves with improvement in disease activity. SF-36 pain questions have good psychometric properties.