COVID-19 stress: Does it augment pain in people with fibromyalgia and might psychological flexibility protect against this influence?

Background: Stress might augment pain in people with fibromyalgia, possibly through sensitization of the central nervous system. The COVID-19 pandemic offers a unique opportunity to examine this mechanism. If it holds, the link between COVID-19 stress and pain would be stronger in people with fibromyalgia than in people without it. Additionally, psychological flexibility might act as a resilience factor, reducing pain severity. If psychological flexibility buffers the impact of stress on pain in people with fibromyalgia, then enhancing psychological flexibility may be of value. Objectives: To determine the association between COVID-19 stress and pain severity in people with fibromyalgia, as compared to people without fibromyalgia, and whether psychological flexibility buffers the impact of stress on pain severity. Methods: In a repeated cross-sectional design, we analysed questionnaire data from two independent surveys. The data collection has been described in a previous study of mental well-being in people with inflammatory rheumatic diseases.[1] The current study analysed data from people with and without fibromyalgia. Data were collected before the COVID-19 pandemic (2018; fibromyalgia: n=145, no fibromyalgia: n=386) and at the first peak of the pandemic in the Netherlands (2020; fibromyalgia: n=270, no fibromyalgia: n=1259). Stress due to the pandemic, psychological flexibility, and pain were subjected to regression analyses. Two operationalisations of stress were analysed: self-reported stress levels during the peak of the pandemic in 2020, and a comparison of assessments in 2018 and 2020 (assuming higher stress levels during the pandemic peak in 2020). Results: In regression analyses, stress during the pandemic (p<.001), having fibromyalgia (p<.001), and lower psychological flexibility (p<.001) were all associated with more severe pain, but the interactions showed that the strength of the association of stress with pain was not different in people with fibromyalgia compared to people without fibromyalgia (p=.76 and p=.28 for the two operationalization of stress, respectively). Another interaction indicated that psychological flexibility was a potential buffer against the association between self-reported stress and pain in the first operationalisation of stress (p=.04), but not in the second (p=.44). The significant but small interaction is shown in the Figure 1. It suggests that pain is higher in people with low psychological flexibility and higher stress levels during the pandemic. This effect was not specific to fibromyalgia. Conclusion: Overall, the significant main effects show that negative states, such as stress related to the pandemic and low psychological flexibility, are associated with another negative state: pain. A small interaction effect suggests that psychological flexibility may protect against the impact of COVID-19 stress on pain, both in people with and without fibromyalgia. However, the analyses reject our hypothesis that COVID-19 stress would augment pain especially in people with fibromyalgia