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Interactions between disease-related inflammatory processes and the development of several morbidities have been well-studied in RA, particularly heart disease. This is not the case for the often-lethal SSc (estimated standardized mortality ratio between 2.5 and 4.0). Similarly, there are no studies comparing the most relevant comorbidities between SSc and RA. Therefore, the authors compared the prevalence of comorbidities in two multicenter, matched-cohorts of patients with SSc and RA.
Comorbidities were examined between 2016 and 2017 in 408 consecutive patients with SSc from six academic rheumatology centers in Greece, who were matched 1:1 for age and sex with 408 RA patients participating in the Greek Rheumatology Society's RA Study Group. Among the 408 patients with SSc included in the study, 55% had the diffuse disease subtype, 89% were women, and the mean age at inclusion was 58.4 ±14.5. Duration of the condition was 10.1 ± 7.7 years in the SSc group and 9.2 ± 7.8 years for the RA group, which was not a significant difference, and no differences were seen in corticosteroid treatment (48% vs 45%) or smoking (25.4% vs 31.3%).
Body mass index was higher in the RA group (26.5 vs 24.2 kg/m2, P=0.001). Ten comorbidities were evaluated e.g., dyslipidemia, diabetes mellitus (DM), arterial hypertension, smoking, coronary artery disease (CAD), stroke, chronic obstructive pulmonary disease (COPD), osteoporosis, neoplasms, and depression.
No differences were seen between the SSc and RA groups for the prevalence of arterial hypertension (31.8% vs 30.6%, P=0.742), although there was a trend toward a lower prevalence of ischemic stroke in the SSc group (1.2% vs 2.9%, OR 0.40, 95% CI 0.14-1.17, P=0.085).
The prevalence of malignancy did not differ overall between the SSc and RA groups (4.2% vs 4.7%, OR 0.89, 95% CI 0.46-1.74, P=0.733), but there were differences in the types of malignancies seen. For the SSc group, the most common was lung cancer (41%), while in the RA group, hematologic malignancies (36%) and breast cancer (36%) were predominant. The frequency of lung cancer in SSc may be explained by the high rate of interstitial lung disease in these patients, the researchers stated.
The prevalence of dyslipidemia was 17.7% and 30.2% for patients with SSc and RA, respectively, and for diabetes, the prevalence was 5.6% in SSc compared with 11.8% for RA, for crude odds ratios of 0.50 (95% CI 0.36-0.69) and 0.45 (95% CI 0.27-0.75), according to Dimitrios Vassilopoulos, MD, of the University of Athens, and colleagues.
Yet, there were no differences in coronary events, which had occurred in 2.7% of SSc patients and 3.7% of RA patients (OR 0.74, 95% CI 0.34-1.62, P=0.0445), or stroke in 1.9% vs 3.4% (OR 0.55, 95% CI 0.21-1.32, P=0.195), the researchers reported online.
For other comorbidities, no differences were seen in the rates of chronic obstructive pulmonary disease or osteoporosis, but almost twice as many patients with SSc had depression (22% vs 12%, OR 2.07, 95% CI 1.42-3.03, P=0.001).
The researchers also looked for differences between the diffuse and limited subtypes of SSc, and found that depression was significantly more common in the diffuse SSc subgroup compared with RA (27.2% vs 11.9%, OR 2.753, 95% CI 1.675-4.523, P=0.001).
"The most interesting result of the present study is that no significant differences in the occurrence of cardiovascular events were noted between patients with SSc and patients with RA, despite the fact that the prevalence of dyslipidemia and diabetes mellitus, two major risk factors for the development of cardiovascular disease, was almost double in RA compared to SSc," the researchers observed.
Certain study limitations need to be addressed e.g., females were predominantly included in this non-randomized trial. There was also a lack of information about concomitant immunosuppression and depression inferred based solely on a prescription for antidepressants following psychiatric evaluation.
Source Reference Arthritis Research & Therapy, Dec. 4, 2018, DOI: 10.1186/s13075-018-1771-0