We investigated long-term changes in symptom burden in patients with FM who had participated in a mindfulness-based group-program, the VTP, followed by physical activity counselling. Just over half of the participants in the intervention group responded to the electronic self-reported questionnaires at the 24-month follow-up. Statistically significant improvements were observed in FM severity, pain, fatigue, and self-efficacy for physical activity compared to baseline, but there were no significant changes between 12 and 24-month follow-up. There was also a sustained improvement in the tendency to be mindful. These changes were of small to moderate magnitude and were not reflected in participants’ self-perceived improvement in health status.

FM is known to be a fluctuating condition with symptoms that vary over time. It is possible for some patients, particularly those who are diagnosed early, to recover from the diagnosis [17]. To increase the likelihood of decreasing symptom burden and promoting recovery, we included participants who had recently been diagnosed with FM. However, only one participant demonstrated recovery based on the PSD score. Most participants reported experiencing symptoms for several years, suggesting that there may still be a delay in diagnosing individuals with FM. Our findings are consistent with a large two-year observational study in the United States involving 226 FM patients, which showed that the majority of patients still met the FM diagnosis criteria after two years [17]. However, our study demonstrated that there was a displacement of participants from ‘very severe’ to ‘severe’ disease, indicating a slight improvement in symptom burden.

Previous research has shown that the VTP improved psychological distress, fatigue, and self-efficacy in patients with inflammatory arthritis [10] and chronic pain [18]. Although only a few participants reported better health status in the present study, the small to moderate long-term improvements in pain and other symptoms may be attributed to the participants having integrated new attitudes and practices into their lives. However, there were no significant improvements at 24 months compared to 12-month data, suggesting that regression to the mean may be an explanation of the observed change.

From a clinical perspective, a critical question is how we can strengthen patients’ ability to manage their daily lives and maintain their health with their fluctuating FM condition. The VTP aims to increase participants’ awareness of their internal and external resources and strengthen their ability to cope with stress through mindfulness techniques. The group-counselling encourages a non-judgemental, non-striving and friendly attitude towards oneself and helps participants reduce their struggle to control pain and promote acceptance, which are the core values in mindfulness-based interventions [5]. A qualitative sub-study involving six FM patients who had completed the VTP found that the program had helped participants adopt a more accepting attitude towards themselves, cultivate belief in their coping abilities, and shift their attention from a disease perspective to a health-promoting perspective [19]. Participants described continuing this process after completing the program [19]. However, these changes could not be captured with the quantitative measures we applied in our study. Although we cannot generalise from a small qualitative study, it indicates that other coping measures might have been more relevant to capture changes.

Physical activity should be recommended to all patients with FM [2]. In our study, participants were offered low-threshold physical activity counselling over a 12-week period to guide them into activities that they could easily continue after the 12-month period. However, less than 50% of the participants completed the physical activity intervention. Therefore, it was not possible to determine whether this had influenced the participants’ health status. This issue has been discussed in a previous publication [7]. There was an increase in participants’ self-efficacy for physical activity over the follow-up time-points, but this was not reflected in patients reporting being physically active.

Most participants reported no change in their perceived health status over the two-year period. The validity of PGIC as a measure for long-term follow-up in FM can be questioned. In a real-life assessment of the validity of PGIC in FM, longer duration of follow-up was identified as a predictor of lower patient impression of change. Patient reporting may be influenced by recall bias, reinterpretation of symptom meanings, and other life events that have impacted their health [15].

Only a few intervention studies have followed FM patients over two years. A two-year follow-up cohort study on recently diagnosed FM patients demonstrated that patients with fewer physical limitations experienced more health improvements if they were working and had a positive attitude towards participating in a healthcare interventions [20]. In our study, all patients had participated in a healthcare intervention. However, we did not find any associations between work status and improvement in health.

One major limitation in our study is that we could not compare the intervention and control groups at the 24-month follow-up. Therefore, we cannot confirm whether the moderate changes observed were due to natural fluctuations in symptoms or if participants had integrated new practices that had influenced their symptom perception. Additionally, just over half of the patients who participated in the intervention responded at the 24-month follow-up. It is possible that these participants had a more positive attitude towards the intervention and thus practiced what they learned. However, we did not detect significant differences at baseline between those who responded at 24 months, and those who did not. Although ethical reasons may justify offering the control-group participants the intervention after a one-year follow-up, we still recommend more controlled trials with a two-year follow-up to further explore the long-term impact of mindfulness-based interventions. Furthermore, it is a need to explore how interventions can be adapted to individual patients’ needs and what characterizes patients who benefit from mindfulness-based interventions.

In this 24-month follow-up study, individuals with FM who had participated in the VTP followed by physical activity counselling demonstrated small to moderate improvements in patient-reported symptoms and FM severity. However, no improvements were observed when compared to the 12-month follow-up. The improvements were not reflected in patients’ self-perceived health status. Because we were unable to compare with a control group at 24 months, changes in symptoms may be attributed to a shift patients’ perceptions of their disease and coping abilities, as well as natural fluctuations in symptoms or regression to mean.