Background & Aims
Diagnoses of chronic pain conditions are often based on the presence of a threshold number of symptoms. This places equal weighting on each criterion, and means there can be variability in the presentations of individuals with the same diagnosis (Maixner et al., 2016; Hagen et al., 2006; Tekinta? et al., 2022). There are also often accompanying characteristics that are outside the selection criteria but are observed with high frequency, and thus could be relevant for understanding underlying mechanisms. It is possible that some symptoms or factors are more important for the experience or progression of a given condition than others, and for differentiating between conditions. We used network analysis to 1) gain deeper insights into the interplay between somatic and sensory symptoms in chronic pain (regardless of diagnosis), and 2) separately determine and compare networks for Complex Regional Pain Syndrome (CRPS), Fibromyalgia, other chronic pain conditions, and pain-free controls.
Methods
The network models were estimated on secondary self-report data from 796 individuals with chronic pain and 234 pain-free controls (Ten Brink et al., 2020) . The analysis plan was developed and finalised on simulated data without assessing the original dataset. Using Mixed Graphical Models, we examined pairwise relationships among 76 variables, including 73 somatic and sensory symptoms (e.g., dizziness, headache, and sensitivity to noise, caffeine, and bright light), demographic information such as age and gender, and clinical scales of depression (PHQ-9) and anxiety (GAD-7). We investigated the relationship between these variables by conducting weighted networks for chronic pain (regardless of diagnosis), distinct diagnoses (CRPS, Fibromyalgia), and healthy control data. This allowed us to look for the most important symptoms and symptom connections both regardless of, and within, each diagnostic label.
Results
In each pain model (overall chronic pain regardless of diagnosis, CRPS, and Fibromyalgia), gender consistently appeared as the most influential variable of the network, while gender did not strongly influence the network of the control group. In the overall pain network (including all chronic pain regardless of diagnostic label), the strongest connection was between gender and increased sexual drive. However, the networks showed distinct symptomatic patterns when separated by condition. Within the network for those diagnosed with CRPS, the strongest connection was between gender and menstrual cramps. Within the network for people with Fibromyalgia, the strongest connection was between stomach pain and digestive system problems. The healthy control network’s strongest association was between difficulties with walking and falling more frequently, with the most influential symptom being falling frequently.
Conclusions
The results suggested that gender plays an important role in the experience and expression of somatic and sensory symptoms in chronic pain regardless of the specific diagnoses, in contrast with the absence of gender’s influence for the control group. Relationships that are apparent in the networks for the pain groups and not in the pain-free control network suggests that they specifically relate to the pain experience. Specifically, In the context of CRPS, a significant association between menstrual cramps and gender suggests potential hormonal influences on the other experienced symptoms. Within the Fibromyalgia network, the strong link between stomach pain and digestive issues may suggest the relevance of gastrointestinal concerns in this condition. Determining common and distinct clusters of across different diagnoses could provide insights into the potential roles and mechanisms of somatic and sensory symptoms in chronic pain.
References
Hagen, E.M. et al. (2006) ‘Comorbid Subjective Health Complaints in Low Back Pain’, Spine, 31(13), p. 1491. Available at: https://doi.org/10.1097/01.brs.0000219947.71168.08.
Maixner, W. et al. (2016) ‘Overlapping Chronic Pain Conditions: Implications for Diagnosis and Classification’, The Journal of Pain, 17(9, Supplement), pp. T93–T107. Available at: https://doi.org/10.1016/j.jpain.2016.06.002.
Snekkevik, H. et al. (2014) ‘Fatigue and Depression in Sick-Listed Chronic Low Back Pain Patients’, Pain Medicine, 15(7), pp. 1163–1170. Available at: https://doi.org/10.1111/pme.12435.
Tekinta?, N.S. et al. (2022) ‘Functional Somatic Symptoms and Their Predictors in Patients with Major Depressive Disorder and Fibromyalgia Syndrome’, Archives of Neuropsychiatry, 59(4), pp. 274–280. Available at: https://doi.org/10.29399/npa.28057.
Ten Brink, A.F. et al. (2020) ‘Bodily changes and sensory sensitivity in complex regional pain syndrome and fibromyalgia’, Pain, 161(6), pp. 1361–1370. Available at: https://doi.org/10.1097/j.pain.0000000000001830.
Presenting Author
Orsolya Szekely
Poster Authors
Topics
- Specific Pain Conditions/Pain in Specific Populations: Complex Regional Pain Syndrome (CRPS)