Racial and ethnic determinants of psoriatic arthritis phenotypes and disease activity.

OBJECTIVE: Individuals of racially and ethnically diverse backgrounds are underrepresented in psoriatic arthritis (PsA) research/clinical trials, despite evidence that their disease presentation, severity and course may be distinct. Here we aim to describe how race, ethnicity and other socioeconomic factors inform disease characteristics in PsA. METHODS: 817 consecutive patients with PsA from a large, diverse metropolitan area, were enrolled in an observational, longitudinal registry. Demographics, medical history, medication use, and psoriatic disease phenotype and activity were all recorded and analyzed. RESULTS: The population was 77.4% non-Hispanic White, 2.2% Black, 7.1% Asian, and 9.9% identified as other races or multiracial, and 11.8% identified as Hispanic. Hispanic and non-White individuals had higher tender joint counts (p= 0.033) with similar swollen joint counts (p= 0.308) and medication use (p= 0.171). They also had high rates of radiographic axial disease. Hispanic individuals were significantly more likely to have higher tender joint counts (p= 0.029), higher RAPID3 scores (p= 0.004), and moderate-severe psoriasis (p= 0.010) compared with non-Hispanic White individuals. CONCLUSION: In this diverse cohort, 22.6% of patients identified as underrepresented racial and/or ethnic groups, mostly Asian or Hispanic. Despite similar swollen joint counts and medication use, non-white individuals have higher tender joint counts compared with white individuals. Phenotypically, they also were more likely to have radiographic axial involvement. These findings may reflect differences in PsA presentation, experience and outcomes in individuals of various racial and ethnic groups, which need to be taken into consideration in clinical care and research design.

Bayesian additive regression trees for multivariate skewed responses.

This paper introduces a nonparametric regression approach for univariate and multivariate skewed responses using Bayesian additive regression trees (BART). Existing BART methods use ensembles of decision trees to model a mean function, and have become popular recently due to their high prediction accuracy and ease of use. The usual assumption of a univariate Gaussian error distribution, however, is restrictive in many biomedical applications. Motivated by an oral health study, we provide a useful extension of BART, the skewBART model, to address this problem. We then extend skewBART to allow for multivariate responses, with information shared across the decision trees associated with different responses within the same subject. The methodology accommodates within-subject association, and allows varying skewness parameters for the varying multivariate responses. We illustrate the benefits of our multivariate skewBART proposal over existing alternatives via simulation studies and application to the oral health dataset with bivariate highly skewed responses. Our methodology is implementable via the R package skewBART, available on GitHub.

Paradoxical Effects of Depression on Psoriatic Arthritis Outcomes in a Combined Psoriasis-Psoriatic Arthritis Center.

Backgroud: Psoriatic arthritis (PsA) is a chronic, inflammatory arthritis that, when left untreated, can lead to erosions, deformities and decrease in quality of life. PsA is known to be associated with multiple comorbidities, including cardiovascular, metabolic and mental health syndromes, all of which can increase its overall morbidity and mortality. Objective: To characterize a cohort of patients with PsA and understand the impact of depression on PsA outcome measures. Methods: 527 consecutive patients with PsA were enrolled in an observational, longitudinal registry that followed them prospectively at standard of care visits. Demographics, medical history, medication use, and clinical exam were all recorded. Results: Depression was reported in 22.8% of the population, anxiety in 18%, and attention deficit hyperactivity disorder in 4%. Depression was more common in female participants (P < .001). At baseline, individuals with PsA and concomitant depression had similar tender and swollen joint counts and RAPID3 compared to those without depression, and had lower body surface area affected by psoriasis (P = .04). At year one, all patients had improvement in clinical outcomes. However, patients with depression had a significantly higher tender joint count compared to those without depression (P = .001), despite similar swollen joint count and body surface area. Conclusion: In patients with depression, there is a discrepancy between improvement in physician assessed measures and patient reported outcomes. These observations underscore the importance of addressing depression and psychological distress as part of PsA treatment outcomes and points towards the need to address residual pain through co-adjuvant approaches.