The distribution of HLA-B27 subtype in patients with ankylosing spondylitis in Northern Norway

Psoriatic arthritis, axial spondyloarthritis and rheumatoid arthritis in Norway: nationwide prevalence and use of biologic agents

OBJECTIVE

To estimate the prevalence of psoriatic arthritis (PsA), axial spondyloarthritis (axSpA) and rheumatoid arthritis (RA) and the use of biologic agents in these diseases in Norway.

METHODS

From the Norwegian Patient Registry (NPR), we identified as PsA, axSpA and RA patients ≥18 years those with ≥2 recorded episodes with diagnostic coding for index disease (L40.5, M07.0-M07.3 for PsA; M45, M46.0, M46.1, M46.8 and M46.9 for axSpA; M05-M06 for RA). We calculated the point prevalence of PsA, axSpA and RA as per the 1^st of January 2017 in the Norwegian adult population (age ≥18). Dispensed disease-modifying antirheumatic drug (DMARD) prescriptions were obtained from the Norwegian Prescription Database and biologic DMARDs given in hospitals from the NPR.

RESULTS

The point prevalence of PsA, axSpA, RA, and any of these diseases in total was 0.46%, 0.41%, 0.78%, and 1.56%, respectively. Among women, the prevalence of PsA, axSpA, and RA was 0.50%, 0.37%, and 1.10%, and among men 0.43%, 0.45%, and 0.46%, respectively. In 2017, 27.3% of RA patients, 25.7% of PsA patients and 35.1% of axSpA patients used biologic DMARDs. Treatment with biologics was more frequent in younger age groups in all three diseases, and became more infrequent especially after age ≥55 years.

CONCLUSION

In Norway, the combined prevalence of PsA, axSpA, and RA was over 1.5%. Reflecting the good overall access to highly effective but costly biologic treatments, more than a fourth of these patients used biologic agents, which corresponds to over 0.4% of Norwegian adult population.

Incidence, sociodemographic factors and treatment penetration of rheumatoid arthritis and psoriatic arthritis in Norway

OBJECTIVES

To evaluate nationwide incidence, sociodemographic associations and treatment penetration of rheumatoid arthritis (RA) and psoriatic arthritis (PsA) in Norway.

METHODS

The study combined data from nationwide registries on the total Norwegian adult population (age ≥ 18). From the Norwegian Patient Registry, incident RA and PsA cases during 2011-2015 were identified with records of first and second healthcare episodes listing RA/PsA diagnostic codes, and ≥ 1 episode in an internal medicine or rheumatology unit with RA/PsA code during the two-year period after the first episode. Dispensed DMARD prescriptions were obtained from the Norwegian Prescription Database. Persons with dispensed DMARD prescriptions or biologic DMARDs given in hospitals > 12 months before the index date were excluded.

RESULTS

Incidence of RA/PsA in Norway was 42/26 per 100,000 person-years (55/28 among women and 28/23 among men). RA peak incidence was observed at ages 70-79 in both sexes, whereas the peak incidence of PsA occurred at ages 50-59. Age- and sex-standardized incidences of RA and PsA were lower among persons with higher education levels. Within a year from the index date, 82.4/57.4% of RA/PsA patients used synthetic DMARDs while 9.4/9.5% used biologic DMARDs.

CONCLUSIONS

Register-based incidence estimates for RA and PsA in Norway are similar to other Nordic countries, but slightly higher than in previous Norwegian studies. Furthermore, we found that higher socioeconomic status was associated with lower incidence of both RA and PsA. Although conventional synthetic DMARDs were less often used in early PsA than RA, frequency of biologic DMARD prescriptions was comparable.

Associations between HLA-B27 subtypes and outcomes in Thai children with enthesitis-related arthritis

OBJECTIVE

Expression of human leukocyte antigen B27 (HLA-B27) has been identified as a predictor of severe disease in enthesitis-related arthritis (ERA) patients. However, the associations between HLA-B27 subtypes and outcomes of this disease are still unclear. Here, we examined the distributions of HLA-B27 subtypes among ERA patients and the associations with disease outcomes.

METHODS

This was a historical cohort study of ERA patients. Patients were followed from diagnosis to the most recent visit. Relationships between outcomes and the HLA-B27 subtype were assessed by mixed-effect regression, Kaplan-Meier survival, and Cox proportional hazards regression analyses.

RESULTS

Of the 66 ERA patients, 50 HLA-B27-positive (86% male) and 16 HLA-B27-negative (69% male) patients were included in this study. Patients with HLA-B27-positive were classified into HLA-B*27:04-positive (84%), including combined HLA-B*27:04 and HLA-B*27:07 (2%), and HLA-B*27:04-negative (16%), including HLA-B*27:05 (10%), HLA-B*27:06 (2%), HLA-B*27:07 (2%), and HLA-B*27:15 (2%). HLA-B*27:04-positive (83.3%) and HLA-B*27:04-negative patients (100%) had refractory disease more than HLA-B27-negative patients (37.5%, p = 0.001). HLA-B*27:04-negative patients (57%, 1.73 years) had relapsing disease more and earlier than HLA-B*27:04-positive (35%, 5.54 years) and HLA-B27-negative patients (40%, 6.92 years; p < 0.001). Furthermore, HLA-B*27:04-negative was predictors of refractory disease (HR 4.56, 95%CI 1.40-14.87; p = 0.012) and relapsing disease (HR 3.80, 95% CI 1.18-12.30; p = 0.026). The duration before anti-tumor necrosis factor treatment initiation > 1 year was also a predictor of refractory disease (HR 116.08, 95% CI 14.67-918.26; p < 0.001).

CONCLUSION

HLA-B*27:04 was the most common HLA-B27 subtype in Thai ERA patients. HLA-B*27:04-negative was associated with more unfavorable outcomes than HLA-B*27:04-positive and HLA-B27-negative patients. Key Points • Most ERA patients in Thailand had HLA-B27-positive, and HLA-B*27:04 was the most common HLA-B27 allele in these patients. • The outcomes of ERA were associated with the presence of HLA-B27 and its subtypes. • HLA-B*27:04-negative patients had unfavorable outcomes, including refractory and relapsing disease, compared to HLA-B*27:04-positive and HLA-B27-negative patients.

Polymorphisms of human leukocyte antigen B*27 on clinical phenotype of spondyloarthritis in Chinese

BACKGROUND

In recent years, an ever-increasing number of alleles of human leukocyte antigen B*27 (HLA-B*27) have been identified. This study aimed to establish an updated method for HLA-B*27 subtyping, and to investigate the impact of HLA-B*27 polymorphisms on the clinical phenotype of spondyloarthritis (SpA).

METHODS

Overall, 184 SpA patients were recruited for analyzing diversity of HLA-B*27 via an updated high-resolution polymerase chain reaction amplification with sequence specific primers (PCR-SSP).

RESULTS

The prevalence of HLA-B*27 was 94.0%, and four subtypes were identified including HLA-B*2704 (77.5%), B*2705 (20.2%), B*2707 (1.7%), and B*2724 (0.6%). There was an obvious male predominance (P=.05) and markedly elevated C-reaction protein (CRP) in B*27 positive SpA (P<.01). In multivariate linear regression analysis, the elevated CRP was positively associated with HLA-B*27 positivity (regression coefficient B=46.1, P=.0003), grade of sacroiliitis (B=47.5, P=.0032), and male gender (B=20.4, P=.0041). Notably, a male predilection was also found in B*2705 positive SpA while B*2707 was associated with older age, higher positive family history, and higher prevalence of extra-articular features (all P<.05).

CONCLUSIONS

In this study, an updated PCR-SSP technique to identify increasing alleles of HLA-B*27 was developed and their different effects on clinical manifestations of SpA were demonstrated. Genotyping of HLA-B*27 would shed light on our understanding of the pathogenesis of SpA.

Tumor necrosis factor-α promoter -308/238 polymorphism association with less severe disease in ankylosing spondylitis is unrelated to serum TNF-α and does not predict TNF inhibitor response

OBJECTIVE

Despite the clinical efficacy of tumor necrosis factor inhibitors (TNFi), the manner in which TNF-α contributes to disease in patients with ankylosing spondylitis (AS) remains unresolved. We investigated the relationship between TNF-α gene promoter region polymorphism, serum TNF-α levels, and clinical phenotype.

METHODS

We did a cross-sectional and longitudinal cohort study in TNFi-naive patients with AS (n = 335). Clinical data and biological samples were collected during a research visit with genotyping for TNF-α -238 A/G and -308 A/G performed by Taqman RT-PCR and TNF levels determined by sandwich ELISA. Longitudinal TNF levels were monitored in unselected patients (n = 61).

RESULTS

TNF-α -308 GA/AA genotype was present in 14% and TNF-α -238 GA/AA genotype in 1% of patients. TNF-α -308 GA/AA genotype was associated with a reduced risk of uveitis and better spinal function, while TNF-α -238 GA/AA genotype was associated with later age of onset and lower erythrocyte sedimentation rate (ESR). Serum TNF-α level was lower in patients with AS (151 pg/ml) than in controls (263 pg/ml), because more patients with AS had undetectable serum TNF-α (66 vs 25%, p < 0.001). TNFi treatment did not influence serum TNF-α. There was no effect of TNF-α -308/-238 or HLA-B27 genotype on serum TNF-α or subsequent initiation of TNFi.

CONCLUSION

TNF-α -238 or -308 GA/AA genotypes in patients with AS are associated with signs of less severe disease. Serum TNF-α is, however, undetectable in two-thirds of patients with AS and is not influenced by TNF-α promoter genotype or TNFi therapy. These data suggest a more significant role for TNF-α at local sites of inflammation in AS than through systemic effects.