Vinod Chandran, MBBS, MD, DM, PhD
The differences between patients who have PsA with axial involvement (AxPsA) and patients who have axial spondyloarthritis with psoriasis (AxSpA+PsO) continue to remain a strong area of interest. Regierer and colleagues recently compared 359 patients with AxPsA vs 181 patients with AxSpA+PsO. These patients were enrolled into the RABBIT-SpA prospective longitudinal cohort study. Given the lack of definition of AxPsA, two definitions were used: 1) clinical judgment by the rheumatologist and 2) imaging (x-ray or MRI) findings. Regardless of clinical or imaging definition used, compared with patients who have AxSpA+PsO those with AxPsA were significantly more often women, were older, were less often HLA-B27 positive, and had more frequent peripheral manifestations but less frequent uveitis. The two diseases thus have significant differences; these should be carefully considered while making treatment decisions.
Another major research focus is on the influence of sex on PsA treatment response. Eder and colleagues conducted a post hoc analysis of pooled data from phase 3 randomized controlled trials that included 816 patients with PsA who received tofacitinib, adalimumab, or placebo. They demonstrate that at 3 months, tofacitinib was more efficacious than placebo, irrespective of sex. However, a higher proportion of men vs women receiving tofacitinib achieved minimal disease activity. This might be due to baseline differences in disease activity. The American College of Rheumatology 20/50/70 response rates were comparable. The incidence of treatment-emergent adverse events was similar in men and women receiving tofacitinib. Thus, sex significantly influences achieving low disease state. Understanding the mechanisms underlying sex differences will help improve treatment response rates in women with PsA.
Atherosclerotic vascular disease (ASVD) is an important comorbidity of PsA. Predicting ASVD remains difficult. The triglyceride-glucose (TyG) index — calculated as ln[fasting triglycerides (in mg/dL) × fasting glucose (in mg/dL)/2] — was recently identified as a marker of insulin resistance and ASVD. Xie and colleagues conducted a cross-sectional study in 165 patients with PsA who underwent carotid ultrasound and had data available for the TyG index. In a model that was adjusted for age, sex, comorbidities, smoking, BMI, low-density lipoprotein cholesterol, psoriasis area and severity index, and disease activity index for PsA, the TyG index was significantly associated with the presence of carotid atherosclerosis (adjusted odds ratio [aOR] 2.69; 95% CI 1.02-7.11) as well as carotid artery plaque (aOR 3.61; 95% CI 1.15-11.38). Thus, this easily calculated marker is associated with ASVD independent of demographic, traditional risk factors, and disease activity and needs further evaluation in prospective studies.