Carotid intima-media thickness in fibromyalgia patients: A meta-analysis

Fibromyalgia is a chronic musculoskeletal pain syndrome characterised by prominent somatic symptoms, sleep disturbances, neurocognitive deficits, and psychiatric disturbances. Carotid intima-media thickness (cIMT) is a well-validated tool for cardiovascular risk stratification and prediction of future cardiovascular events. It is speculated that fibromyalgia patients may have autonomic impairment predisposing to a higher cardiovascular event risk.1,2 The aim of this study is to assess the increased risk of cardiovascular complications in these patients. We perform a meta-analysis comparing cIMT in cases and controls to investigate subclinical atherosclerosis in fibromyalgia patients. Existing literature was screened using MeSH terms from PubMed, Embase, and Cochrane databases to identify relevant studies that compare cIMT between fibromyalgia patients and controls. A total of four recent studies were found and were included in this meta-analysis.1-4 For each study, mean age and baseline comorbidities were observed. These studies reported the mean of bilateral carotid arteries cIMT, right and/or left carotid artery cIMT. Statistical analysis was performed with STATA 17.0 using the random effects model, Hedges g equation, and standardised mean difference (SMD) of cIMT between both groups. Publication bias was assessed by the Egger test. Funnel plot is not reported due to a small number of studies. Forest plot was utilised as demonstrated in image 1. From four studies, we included a total of 425 patients, of which 174 had fibromyalgia. Two studies reported the mean of bilateral cIMT, two reported only right cIMT and one reported left-sided cIMT. All the patients in the studies were females. The mean age for patients with fibromyalgia was 45.6 years [Standard deviation (SD) ± 5.16] and for healthy controls, it was 46.2 years [SD ± 8.49]. The mean Body Mass Index (BMI) for cases was 25.9 [SD ± 1.07] and for controls, BMI was 25.1 [SD ± 1.04]. Although all studies reported a higher cIMT value for fibromyalgia patients, two studies reported the difference to be insignificant. The overall standardised mean difference (SMD) of bilateral, left, and right cIMT measurements was 0.57 mm [95%CI: 0.21–0.92], with a summary effect of z = 3.12, p-value < 0.01. Overall SMD for the right carotid artery cIMT difference was not significant [0.32 mm, 95%CI: −0.18–0.81], but the left carotid artery cIMT difference was significant [0.74 mm, 95%CI: 0.07–1.40]. Heterogeneity was noted as I2 = 64.6% (p-value < 0.01). A high heterogeneity has the potential for bias and should be taken into account; a funnel plot was not included due to a small number of studies. Our analysis showed an increased risk of cardiovascular complications measured by cIMT in fibromyalgia patients. There is significantly higher cIMT in fibromyalgia patients compared to healthy controls, implying the presence of subacute atherosclerosis. It will be reasonable to consider establishing screening guidelines or utilising cIMT as a parameter to identify significant atherosclerosis in patients with fibromyalgia and especially in those with additional risk factors.