A variety of clinical indices exist to assess enthesitis in PsA; however, the Leeds Enthesitis Index and Maastricht Ankylosing Spondylitis Enthesitis Score index have been the most frequently used indices in recent clinical trials.
After controlling for the age of psoriasis onset no association of PsA to HLA-C*06:02 (p=0.07) was observed; instead, the most significant association was to amino acid at position 97 of HLA-B (p=1.54×10<sup>-9</sup>) where the presence of asparagine or serine residue increased PsA risk.
Allele frequencies were calculated and logistic regressions were performed, adjusting for HLA-B and HLA-C alleles previously shown to be associated with psoriasis and/or PsA.
Certain HLA-B and HLA-C alleles confer susceptibility to PsA among patients with psoriasis and may be used to identify patients with PsC who may develop PsA.
Clearly, PsV and PsA are highly variable in terms of their clinical manifestations, and this heterogeneity can partially be explained by differences in HLA-associations (HLA-Cw*0602 versus HLA-B*27, for example).
Comparing PsA and psoriasis, the prevalence of HLA-B*27 and HLA-Cw*12 were more common in PsA patients, while the prevalence of HLA-DR*07 was higher in those with psoriasis (p < 0.05).
Flare was defined as change in 28 Joint Disease Activity Score (∆DAS28) ≥1.2 (RA/PsA) or Ankylosing Spondylitis Disease Activity Score (∆ASDAS) ≥1.3 (AxSpA).
Genetic Polymorphisms of <i>Toll-like receptors 2</i> and <i>9</i> as Susceptibility Factors for the Development of Ankylosing Spondylitis and Psoriatic Arthritis.
Impact of Comorbidity on Physical Function in Patients with Ankylosing Spondylitis and Psoriatic Arthritis Attending Rheumatology Clinics. Results from the CARdiovascular in rheuMAtology (CARMA) study.
In contrast, HLA-B*58 was more common in controls than in PsA and psoriasis groups, and the prevalence of HLA-DR*17 was significantly higher in controls than in those with psoriasis.
In PSUMMIT 1 and 2, patients with PsA were randomized to placebo or ustekinumab 45 mg or 90 mg. Enthesitis was assessed at weeks 0 and 24 (Maastricht Ankylosing Spondylitis Enthesitis Score).
Moreover, the genotype of patients in the PsA cohort was shown to be heterogeneous with significant elevations in the frequency of haplotypes containing HLA-B*08, HLA-C*06:02, HLA-B*27, HLA-B*38 and HLA-B*39.
Obesity is linked with late-onset psoriasis and PsA, while normal weight is associated with the presence of the HLA-B*27 allele and an earlier onset of the disease.
PROMs measuring COS domains with at least fair quality evidence for good validity and reliability (and no evidence for poor properties) included the Stockerau Activity Score for PsA (German), Psoriasis Symptom Inventory, visual analogue scale for Patient Global, 36 Item Short Form Health Survey Physical Function subscale, Health Assessment Questionnaire Disability Index, Bath Ankylosing Spondylitis Functional Index, PsA Impact of Disease questionnaire, PsA Quality of Life questionnaire, VITACORA-19, Functional Assessment of Chronic Illness Therapy Fatigue scale and Social Role Participation Questionnaire.
Regression analysis demonstrated a significant association of SI with peripheral joint erosions (p=0.043), PASI maximum (p=0.041), younger age of PsA onset (p=<0.001), presence of HLA-B*0801 (p=0.002) and only marginal significance with HLA-B*2705 (p=0.059).
Some findings can be concluded from the study: (1) the frequency of HLA-B*5701, B*3801, B*39, B*27, Cw*0602, Cw*07, DRB1*0402, and DRB1*0701 were not found to be significantly increased in PsA; (2) no significant differences of TNFalpha promoter alleles at positions -308 and -238 were found between PsA and healthy controls; (3) the trinucleotide repeat polymorphism MICA-A9 was present at a higher frequency in PsA patients, (p(c) < 0.009, RR = 3.34, EF = 0.39); and (4) MICA-A9 polymorphism was found in linkage disequilibrium with HLA-B alleles (B*5701, B*3801) described to be associated with PsA in Caucasians.