Pain Intensity In Idiopathic Inflammatory Myopathies And Rheumatic Diseases
Pain management is central to the medical practice of many medical professionals, especially rheumatologists and pain experts. Pain intensity has important implications, as it often indicates the severity of a disease, its prognosis, and the outcome of specific treatments. Also, evidence shows that pain significantly impacts patients’ health-related quality of life.
A new study assesses the pain level among individuals with idiopathic inflammatory myopathy, systemic autoimmune rheumatic diseases, and its effect on physical health [1].
Introduction
Pain is among the most frequently reported symptoms of many inflammatory diseases, including systemic autoimmune rheumatic diseases. For instance, a recent European multicenter research showed that pain was one of the most reported symptoms of patients with systemic lupus erythematosus [2]. Furthermore, pain intensity is recognized as a cardinal symptom required to diagnose systemic autoimmune rheumatic diseases [3]. However, this is not the same for idiopathic inflammatory myopathy, as many experts have underplayed the importance of pain as a symptom of idiopathic inflammatory myopathy over the years. However, recent evidence suggests that patient reported pain intensity is indeed a significant aspect of the disease experience of individuals living with idiopathic inflammatory myopathy [4].
The growing recognition of the importance of pain in these conditions and its detrimental impact on patient’s quality of life has fueled efforts to create methods to objectively assess it and increase research on the level of pain perception. One such recently developed tool for assessing pain intensity is the Patient-Reported Outcomes Measurement Information System (PROMIS). This paradigm-shifting and reliable tool also assesses physical and mental health and social well-being in various settings, allowing patient status surveillance and facilitating prompt decision-making.
This study aimed to assess pain intensity among a large set of individuals with idiopathic inflammatory myopathies, systemic autoimmune rheumatic diseases, and persons without an autoimmune disease using the PROMIS tool, as well as to investigate the relationship between pain and disease severity, demographics, and quality of life.
The Study Method
This study is a subset of a more extensive and global cross-sectional online survey called the COVAD guidelines. While COVAD was centered around vaccination statistics, a vast amount of supporting data was gathered, including information on pain perception among the respondents diagnosed with autoimmune diseases. Individuals from over ninety-four (94) countries were enlisted for this study. However, only participants over eighteen (18) years old and who had idiopathic inflammatory myopathy or systemic autoimmune rheumatic diseases or other non-autoimmune diseases confirmed by a neurologist, rheumatologist, or any certified medical doctor were included in the study.
The researchers considered the respondents’ pain level over seven days, estimated by a numeral rating scale (NRS), with sociodemographics, specific autoimmune disease subtypes, and physical functionality (physical health state and the capacity to go about daily activities). The PROMIS 10 Global Health instrument was used to measure the general physical health of the participants using 5-category answer scores. Participants were asked to rank their physical health as exceptional, very good, good, fair, or bad. They were also asked to score their capacity to carry out daily tasks and label it as entirely, largely, somewhat, a little, or not at all.
Concerning the disease activity, the study categorized the participants’ disease state over four weeks as active or inactive based on the patient’s opinion, a self-reported physician’s evaluation of the participant’s disease activity, and persistent symptoms despite optimal steroid treatment. Patients on a daily prednisone dose equivalent to ≥10 mg with either active rash, muscle weakness, or arthritis were also considered to have an active illness.
Analysis
Concerning the study’s statistical analysis, quantitative variables were characterized using mean and standard deviation if the data were normally distributed or median and interquartile range (IQR) if the distribution under test could not be assumed to follow a Gaussian curve. Qualitative variables were represented using frequencies. Also, the Kolmogorov–Smirnov test was used to examine the normality of the data. Depending on the data arrangement, continuous variables were compared across age categories using analysis of variance or Kruskal-Wallis.
Furthermore, statistically significant findings among groups were compared using Dunn’s post hoc test. The Chi-square test was used to equate categorical factors between groups, and a negative binomial regression multivariate analysis clustering was done to examine the projected pain NRS across scenarios. A P-value of less than 0.05 was held as statistically significant, and STATA version 16.3 was used for the statistical analysis.
Study Findings
A total of 6988 responses from the COVAD database were analyzed for this study. Approximately fifteen percent (1057) of the responses were from individuals diagnosed with idiopathic inflammatory myopathies (IIM). In comparison, about twenty-eight percent (1950) of the answers were from persons with systemic rheumatic autoimmune disease (AIRDs) and fifty-seven percent (3981) from individuals not diagnosed with autoimmune diseases (wAIDs).
The majority of the respondents (32%) diagnosed with IIM specifically had dermatomyositis, while 247 respondents (23.4%) had inclusion body myositis, and 189 participants (17.9%) had polymyositis. Furthermore, one hundred and sixteen patients (11.0%) were diagnosed with the antisynthetase syndrome, 111 respondents (10.5%) had overlap myositis with other connective tissue disorders, and 56 respondents with IIM (5.3%) had immune-mediated necrotizing myopathies.
Among the 1950 respondents diagnosed with systemic rheumatoid autoimmune disease (AIRDs), there were a total of 869 patients (44.6%) diagnosed with rheumatoid arthritis, 372 patients (19.1%) with systemic lupus erythematosus, 257 patients (13.2%) with ankylosing spondylitis or psoriatic arthritis, 252 patients (12.9%) with systemic sclerosis, 76 patients (3.9%) with primary Sjögren’s syndrome, and 67 patients (3.4%) with systemic vasculitis.
Analysis of the responses of the study participants revealed the following findings:
- The median pain score of patients with idiopathic inflammatory myopathies (IIMs) was significantly higher than that of patients without autoimmune diseases (wAIDs) but substantially lower than that of patients with systemic rheumatic autoimmune diseases (AIRDs).
- Patients with overlap myositis and antisynthetase syndrome had the highest pain scores among the respondents diagnosed with idiopathic inflammatory myositis. On the other hand, inclusion body myositis had the lowest pain perception scores.
- For almost all disease activity scenarios, the predicted pain score of patients with idiopathic inflammatory myopathies was higher than those without autoimmune diseases but lower than those with systemic autoimmune rheumatic disease. The only scenario in which the predicted pain score of patients with IIMs and other AIRDs was similar, with both being higher than wAIDs, was inactive disease based on the patient’s perception.
- Females with idiopathic inflammatory myopathies reported more pain than male patients, irrespective of disease activity. Increasing age was associated with increased discomfort in both active and inactive myopathies.
- Hispanic respondents reported less discomfort in some active categories of idiopathic inflammatory myopathies. Also, Asian respondents generally had lower pain scores compared to other ethnicities.
- IIM patients who reported good or acceptable general health had a higher predicted pain score than those with wAIDs but a lower predicted pain score than those with other AIRDs. On the other hand, the responders with excellent general health status reported no difference in discomfort. AIRDs caused significantly more pain than IIMs in people with poor health, although pain perception among the participants with IIMs was equal to those with wAIDs.
- Also, females reported more pain than males, except those with poor health, where the sexes were equally affected.
- Patients with IIMs who could not do daily activities reported higher levels of pain than those with wAIDs, but lower levels of discomfort than those with other AIRDs. Conversely, patients with profound impairment reported identical pain regardless of their sex.
Discussion
This exceptional study revealed that patients with idiopathic inflammatory myopathies (IIMs) had a higher pain score than those without autoimmune diseases (wAIDs) but a lower score than those with systemic autoimmune rheumatic diseases (AIRDs). This difference was observed at various disease activity and functional status levels. In all categories, there was a correlation between pain intensity and poor functional status and between active disease and pain intensity in patients with IIMs and AIRDs. It implies that individuals diagnosed with idiopathic inflammatory myopathies and systemic autoimmune rheumatic diseases are more likely to experience severe pain and a reduction in their functionality and other health-related quality of life than those without autoimmune diseases. The myopathies with the highest pain scores were overlap myositis and antisynthetase syndrome. The researchers believe that the frequent association of antisynthetase syndrome and overlap myositis with arthritis may explain this occurrence.
The study also found that men and individuals without autoimmune diseases were less likely to report discomfort than those with rheumatic diseases. Additionally, it showed that age and ethnicity could impact pain perception in certain circumstances.
Many other studies corroborate these findings [6] [7] [8]. One such study affirms that persons diagnosed with idiopathic inflammatory diseases are likely to experience a significant reduction in their quality of life [6].
Concerning the disparity in pain perception among sexes, previous studies have suggested that gender influences a person’s expression of pain and its effect on their quality of life [6].
In the same vein, ethnicity has been shown to impact pain perception. This study revealed that compared to people of other races, Asians and Hispanics reported feeling less pain. Experts have suggested that coping strategies, perspectives on health, and other environmental characteristics peculiar to different ethnicities may account for these findings [9].
Limitations of the Study
Some caveats to this study must be taken into account. They include:
- The patients’ diagnoses were self-reported in this study, predisposing its findings to measurement bias.
- The presence of co-morbidities like psychiatric disorders like depression among the respondents and other factors such as socioeconomic status and level of education may impact pain perception and expression of pain levels.
- The cross-sectional design of this study and the prospective nature of several confounding co-variables makes it impossible to assess a causal relationship between the parameters.
- Several of the participants used nonsteroidal anti-inflammatory drugs during the study. These medications could significantly affect their pain perception.
- This study employed the convenience sampling method, prone to selection bias.
- Lastly, this study did not investigate aspects of pain besides intensity, such as duration, location, and other traits that may be related to and significant to the pain experience.
Conclusion
This paradigm-shifting study dismisses previously held notions that idiopathic inflammatory myopathies are predominantly pain-free. It shows that patients with these ailments experience significant pain and reduced functionality, albeit slightly lesser than individuals with systemic autoimmune rheumatic diseases.
References
- Shinjo, S. K., Kim, M., Hoff, L. S., Missé, R. G., Sen, P., Naveen, R., Day, J., Cordeiro, R. A., Júnior, J. G., Chatterjee, T., Lilleker, J. B., Agarwal, V., Kardes, S., Milchert, M., Gheita, T., Salim, B., Velikova, T., Gracia-Ramos, A. E., Parodis, I., … COVAD Study Group. (2023). Pain in individuals with idiopathic inflammatory myopathies, other systemic autoimmune rheumatic diseases, and without rheumatic diseases: A report from the COVAD study. International Journal of Rheumatic Diseases, 26(4), 727–739. https://doi.org/10.1111/1756-185X.14636
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- Sen, P., Gupta, L., Lilleker, J. B., Aggarwal, V., Kardes, S., Milchert, M., Gheita, T., Salim, B., Velikova, T., Gracia-Ramos, A. E., Parodis, I., O’Callaghan, A. S., Nikiphorou, E., Tan, A. L., Cavagna, L., Saavedra, M. A., Shinjo, S. K., Ziade, N., Knitza, J., Kuwana, M., … COVAD Study Group (2022). COVID-19 vaccination in autoimmune disease (COVAD) survey protocol. Rheumatology international, 42(1), 23–29. https://doi.org/10.1007/s00296-021-05046-4
- Graham, C. D., Rose, M. R., Grunfeld, E. A., Kyle, S. D., & Weinman, J. (2011). A systematic review of quality of life in adults with muscle disease. Journal of neurology, 258(9), 1581–1592. https://doi.org/10.1007/s00415-011-6062-5
- Chung, Y. L., Mitchell, H. L., Houssien, D. A., Al-Mahrouki, H., Carr, A. J., & Scott, D. L. (2001). A comparative study of outcome in myositis and other musculoskeletal disorders assessed using the Nottingham health profile. Clinical and experimental rheumatology, 19(4), 447–450.
- Saygin, D., Oddis, C. V., Dzanko, S., Koontz, D., Moghadam-Kia, S., Ardalan, K., Coles, T. M., & Aggarwal, R. (2021). Utility of patient-reported outcomes measurement information system (PROMIS) physical function form in inflammatory myopathy. Seminars in arthritis and rheumatism, 51(3), 539–546. https://doi.org/10.1016/j.semarthrit.2021.03.018
- Orhan, C., Van Looveren, E., Cagnie, B., Mukhtar, N. B., Lenoir, D., & Meeus, M. (2018). Are Pain Beliefs, Cognitions, and Behaviors Influenced by Race, Ethnicity, and Culture in Patients with Chronic Musculoskeletal Pain: A Systematic Review. Pain physician, 21(6), 541–558. https://pubmed.ncbi.nlm.nih.gov/30508984/
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