Risk Factors for Progression from Subclinical to Clinical Phase of Psoriatic Arthritis: A Case-Control Study

The relationship between blood lipid and risk of psoriasis: univariable and multivariable Mendelian randomization analysis

Background

Psoriasis is a chronic inflammatory skin disease. Dyslipidemia may be a risk factor of psoriasis. But the causal relationship between psoriasis and blood lipid still remains uncertain.

Methods

The two data of blood lipid were obtained from UK Biobank (UKBB) and Global Lipid Genetics Consortium Results (GLGC). The primary and secondary database were from large publicly available genome-wide association study (GWAS) with more than 400,000 and 170,000 subjects of European ancestry, respectively. The psoriasis from Finnish biobanks of FinnGen research project for psoriasis, consisting of 6,995 cases and 299,128 controls. The single-variable Mendelian randomization (SVMR) and multivariable Mendelian randomization (MVMR) were used to assess the total and direct effects of blood lipid on psoriasis risk.

Results

SVMR estimates in primary data of blood lipid showed low-density lipoprotein cholesterol (LDL-C) (odds ratio (OR): 1.11, 95%, confidence interval (CI): 0.99-1.25, p = 0.082 in stage 1; OR: 1.15, 95% CI: 1.05-1.26, p = 0.002 in stage 2; OR: 1.15, 95% CI: 1.04-1.26, p = 0.006 in stage 3) and triglycerides (TG) (OR: 1.22, 95% CI: 1.10-1.35, p = 1.17E-04 in stage 1; OR: 1.15, 95% CI: 1.06-1.24, p = 0.001 in stage 2; OR: 1.14, 95% CI: 1.05-1.24, p = 0.002 in stage 3) had a highly robust causal relationship on the risk of psoriasis. However, there were no robust causal associations between HDL-C and psoriasis. The SVMR results in secondary data of blood lipid were consistent with the primary data. Reverse MR analysis showed a causal association between psoriasis and LDL-C (beta: -0.009, 95% CI: -0.016- -0.002, p = 0.009) and HDL-C (beta: -0.011, 95% CI: -0.021- -0.002, p = 0.016). The reverse causation analyses results between psoriasis and TG did not reach significance. In MVMR of primary data of blood lipid, the LDL-C (OR: 1.05, 95% CI: 0.99-1.25, p = 0.396 in stage 1; OR: 1.07, 95% CI: 1.01-1.14, p = 0.017 in stage 2; OR: 1.08, 95% CI: 1.02-1.15, p = 0.012 in stage 3) and TG (OR: 1.11, 95% CI: 1.01-1.22, p = 0.036 in stage 1; OR: 1.09, 95% CI: 1.03-1.15, p = 0.002 in stage 2; OR: 1.07, 95% CI: 1.01-1.13 p = 0.015 in stage 3) positively correlated with psoriasis, and there had no correlation between HDL-C and psoriasis. The results of the secondary analysis were consistent with the results of primary analysis.

Conclusions

Mendelian randomization (MR) findings provide genetic evidence for causal link between psoriasis and blood lipid. It may be meaningful to monitor and control blood lipid level for a management of psoriasis patients in clinic.

The role of ultrasound in screening subclinical psoriatic arthritis in patients with moderate to severe psoriasis

OBJECTIVE

To identify patients in the subclinical psoriatic arthritis (Sub-PsA) phase by ultrasound (US) and provide a solution to screen them.

METHODS

A total of 490 participants with moderate-to-severe psoriasis were evaluated. Among them, 384 participants without arthritis symptoms were enrolled into the silent psoriasis group and 106 participants with arthritis symptoms, called prodromal/active PsA phase, were enrolled into the clinical PsA group. Another 80 non-psoriasis participants were enrolled into the control group. Each participant received clinical assessments and US examinations of 60 joints, 38 tendons, and 40 entheses. We compared the incidences of synovio-enthesitis, synovitis, tenosynovitis, erosion, and dactylitis detected on US among the three groups. Subsequently, on the basis of significant US findings, we distinguished Sub-PsA from psoriasis alone (PsO) in the silent psoriasis group and analyzed the clinical characteristics, mainly including basic clinical characteristics, body surface area (BSA), and Psoriasis Area and Severity Index (PASI) score.

RESULTS

Only synovio-enthesitis significantly differed between the control group and the silent psoriasis group (1.3% vs. 16.1%, p < 0.001). The knee was the most commonly involved site of synovio-enthesitis (79.0%). Taking synovio-enthesitis as the standard, 16.1% of silent psoriasis participants and 12.7% of all psoriasis participants were in the Sub-PsA phase. Furthermore, there were no differences in BSA and PASI among the three phases of PsO, Sub-PsA, and prodromal/active PsA.

CONCLUSIONS

Since the psoriasis patients in Sub-PsA phase was as high as 12.7% in all patients with moderate-to-severe psoriasis, US-detected synovio-enthesitis was recommended routinely for screening them regardless of arthritis symptoms, especially in the lower limbs.

KEY POINTS

• Synovio-enthesitis on ultrasound was significantly associated with subclinical psoriatic arthritis, especially in the lower limbs. • Routine ultrasound evaluation could help screen psoriasis patients in the subclinical psoriatic arthritis phase, which was as high as 12.7% in all psoriasis patients.

The Clinical Characteristics of Psoriatic Arthritis: A Cross-Sectional Study Based on the Psoriatic Arthritis Cohort of West China Hospital

INTRODUCTION

This study aims to describe the demographic, clinical, laboratory, and ultrasonic characteristics of patients with psoriatic arthritis (PsA) in the Psoriatic Arthritis cohort of West China Hospital.

METHODS

In this cross-sectional study, we included patients diagnosed with PsA according to the Classification Criteria for Psoriatic Arthritis, collected their demographic information, medical histories, and treatments, evaluated all domains (skin and nail lesions, tenderness, swelling, enthesitis, dactylitis, and axial arthritis) related to PsA, and then performed descriptive statistical analyses of all data.

RESULTS

A total of 275 patients with PsA were included in this study. The ratio of male to female patients was 2.16:1. Skin lesions preceded arthritis in 86.5% of these patients with PsA with a mean interval of 10.1 years. The metacarpophalangeal (MCP) joints, proximal interphalangeal (PIP) joints of fingers, and sacroiliac joints are the most commonly involved sites of tenderness, swelling, and the spine, respectively. Among all comorbidities, fatty liver has the highest incidence with 33.1%. Finally, we noted that the mean disease duration of PsA was 4.2 years, suggesting a delay in the diagnosis of PsA.

CONCLUSION

Our study proposes that the prevalent population of PsA are male patients with psoriasis over 40 years of age who have a long disease course. For patients with PsA, MCP, PIP joints of fingers, and sacroiliac joints are the most frequently affected anatomical sites. With respect to comorbidities, the association between PsA and fatty liver and the underlying molecular mechanisms are worthy of further exploration.

Development of a Predictive Model for Screening Patients with Psoriasis at Increased Risk of Psoriatic Arthritis

Introduction

This study aimed to develop a predictive model based on ultrasound variables which can be used to screen patients with psoriasis who are prone to progress to psoriatic arthritis (PsA) in clinical practice.

Methods

This is a cross-sectional study conducted in a single center from October 2018 to November 2020. All subjects (non-PsA group, PsA group, and control group) underwent an ultrasound examination and their ultrasound abnormalities were recorded. On the basis of statistical analysis and clinical experts’ advice, several variables were selected for modelling. We used logistic regression to establish the prediction model. To assess the discrimination and accuracy of this model, internal validation and external validation were performed.

Results

A total of 852 patients with psoriasis but without PsA, 261 patients with PsA, and 86 healthy volunteers were included. Ultimately, the predictive model consisted of six variables, namely hand joint power Doppler (PD) signals (grade 0: OR 2.94, 95% CI 1.94–4.47; grade ≥ 1: OR 109.30, 95% CI 14.35–832.27; P < 0.001), wrist joint synovial thickening (grade 1: OR 1.29, 95% CI 0.69–2.43; grade 2: OR 4.30, 95% CI 1.92–9.65; grade 3: OR 11.05, 95% CI 1.01–120.64; P = 0.001), knee joint PD signals (grade 0: OR 1.01, 95% CI 0.56–1.80; grade ≥ 1: OR 14.77, 95% CI 3.99–54.69; P < 0.001), toe joint PD signals (grade 0: OR 1.18, 95% CI 0.78–1.79; grade ≥ 1: OR 5.74, 95% CI 2.84–11.63; P < 0.001), quadriceps tendon and patellar tendon enthesitis (OR 1.95, 95% CI 1.36–2.78, P < 0.001), Achilles tendon and plantar aponeurosis enthesitis (OR 1.63, 95% CI 1.14–2.32, P = 0.007). C-index for the predictive model was 0.80 (95% CI 0.76–0.83). After bootstrapping validation (1000 times), it was confirmed to be 0.79. The external validation showed the accuracy of the predictive model is 0.87 (95% CI 0.69–0.95).

Conclusion

This study succeeded in developing a predictive model with a high degree of accuracy to predict the risk of PsA in patients with psoriasis.

Psoriatic arthritis often occurs in the population of patients with psoriasis. It brings a huge burden and pain to patients. At present, the diagnosis for psoriatic arthritis is very challenging. Numerous research studies have begun to focus on identifying patients with psoriasis at increased risk of psoriatic arthritis. Among a lot of modalities, ultrasound has been considered as a sensitive and convenient tool for screening early psoriatic arthritis. Our study successfully established a predictive model based on ultrasound variables to screen patients with psoriasis at high risk of transiting to psoriatic arthritis. After internal and external validation, it showed great accuracy and generalizability. We recommend that clinicians perform ultrasound screening of patients with psoriasis in clinical routine and get their risk value of transiting to psoriatic arthritis by using this model. For those patients with a high risk of progression to psoriatic arthritis, clinicians should refer them to a rheumatology department as soon as possible so that they could have access to early and effective management which might bring them good clinical and imaging outcomes.