HLA-B27, axial spondyloarthritis and survival

INTRODUCTION

Ankylosing spondylitis (AS), and carriage of HLA-B27 gene in otherwise healthy individuals, are reportedly associated with increased mortality. We evaluated this hypothesis, using data from both a 35-year AS follow-up study and UK Biobank data.

METHODS

In 1985, 363 members of the Swiss AS Patient Society and 806 relatives were screened clinically and then radiographically for AS/axial spondyloarthritis (axSpA). Life expectancy was analysed in 377 axSpA patients having available pelvic radiographs and HLA-B27 status, comparing with matched Swiss population data. Survival in relation to HLA-B27 status in the general population was studied in UK Biobank European-ancestry participants (n=407 480, n=30 419 deaths).

RESULTS

AS patients have increased standardised mortality rate (SMR) compared with the general population (1.37, 95% CI 1.11 to 1.62). This increase was significant for HLA-B27-positive AS (SMR 1.38, 95% CI 1.11 to 1.65). Shortened life expectancy was observed among both HLA-B27-positive AS women (SMR 1.77, 95% CI 1.09 to 2.70) and men (SMR 1.31, 95% CI 1.02 to 1.59). Patients with non-radiographic axSpA (nr-axSpA) had significantly lower SMR: 0.44 (95% CI 0.23 to 0.77), compared with the general population. In the UK Biobank European-ancestry population cohort, HLA-B27 carriage was not significantly associated with any change in mortality (HR 1, 95% CI 0.97 to 1.1, p=0.349, adjusted by sex), in either males (HR 1, 95% CI 0.98 to 1.1, p=0.281) or females (HR 0.96, 95% CI 0.9 to 1, p=0.232), and no increase in vascular disease mortality was observed.

DISCUSSION

AS patients, but not nr-axSpA patients, have a significantly shortened life expectancy. Increased mortality is particularly significant among women with HLA-B27-positive AS. HLA-B27 carriage in the European-ancestry general population does not influence survival, or the risk of death due to vascular disease.

Recurrence of axial spondyloarthritis among first-degree relatives in a prospective 35-year-follow-up family study

Objective

The lifetime recurrence rate (RR) of axial spondyloarthritis (axSpA) among first-degree relatives (FDR) and the effect of proband’s gender, HLA-B27 and radiographic status is unclear. Our 35-year-follow-up family study has enabled these issues to be addressed.

Methods

In 1985, 363 ankylosing spondylitis (AS) probands (members of the Swiss AS Patient Society) and 806 FDR recruited into the study, completed questionnaires regarding axSpA manifestations, underwent a physical examination and most also underwent pelvic radiography and HLA-B27 typing. At follow-up in 2018–2019, of the former participants whose current addresses could be retrieved, 162 had died and 485 (125 patients with AS plus 360 FDR) completed a postal questionnaire.

Results

At follow-up, 48 of 177 HLA-B27(+) FDR had developed axSpA, an RR of 27.1% (95% CI 20.6% to 33.7%). 27/148 (18.2%) children of AS probands (modified New York (mNY) criteria) were affected versus 2/50 (4.0%) children of non-radiographic axSpA probands (p=0.0138, OR=5.36; 95% CI 1.23 to 23.40). Children of female probands were more often affected (12/22; 54.5%) than of male probands (15/78; 19.2%) (p=0.0003; OR=4.89; 95% CI 1.96 to 12.23). This increased risk applies equally to sons and daughters.

Conclusion

The lifetime RR of axSpA for HLA-B27(+) FDR is substantial (27.1%), and disease severity (as defined by radiographic sacroiliitis by the mNY criteria) is an additional risk factor. Affected mothers pass on the disease significantly more often to their offspring than do affected fathers. These findings may lead to better assessment of lifetime risk for axSpA in the offspring. Moreover, investigation of this gender effect may uncover additional putative disease susceptibility factors.

Heterogeneity of axial spondyloarthritis: genetics, sex and structural damage matter

OBJECTIVE

Axial spondyloarthritis (axSpA) comprises both radiographic and non-radiographic disease. However, the paucity of specific objective measures for the disease and current classification criteria showing suboptimal specificity contribute to disease heterogeneity observed in clinical practice and research. We used a historical cohort of patients with axSpA to assess sources of heterogeneity.

METHODS

The study involved 363 axSpA probands recruited from membership of the Swiss Ankylosing Spondylitis Patient Society. Participants underwent examination by a rheumatologist, completed questionnaires and provided blood samples for HLA typing. Patients underwent radiography of sacroiliac joints and were categorised according to the New York (NY) criteria (ankylosing spondylitis (AS) or non-radiographic axSpA (nr-axSpA)) and HLA-B27 status. Genetic characterisation by single nucleotide polymorphism microarray was performed and AS polygenic risk scores (PRS) were calculated.

RESULTS

Considerable heterogeneity was observed. The male to female ratio for AS (NY+) was 3:1, but 1:1 for nr-axSpA. For HLA-27(+) AS, the ratio was 2.5:1, but nearly 1:1 for HLA-B27(-) disease. Women with nr-axSpA had strikingly lower mean PRS and lower HLA-B27 prevalence than men with nr-axSpA or NY(+) male and female patients with AS. PRS was able to distinguish male but not female patients with nr-axSpA from related healthy first-degree relatives. Radiographic sacroiliitis was strongly associated with HLA-B27, especially in men.

CONCLUSION

Women clinically diagnosed with axSpA but without radiographic sacroiliitis as a group have a disease that is distinct from AS by the modified New York criteria overall and from nr-axSpA in men. Given the high degree of heterogeneity, stratified or adjusted analysis of effectiveness studies is indicated, taking genetics, sex and radiographic damage (sacroiliitis) into account.

Factors predicting axial spondyloarthritis among first-degree relatives of probands with ankylosing spondylitis: a family study spanning 35 years

Objective

Factors predicting axial spondyloarthritis (axSpA) among first-degree relatives (FDRs) of ankylosing spondylitis (AS) patients need to be defined. We investigated the predictive value of the probands’ HLA-B27 and radiographic sacroiliitis status on disease occurrence among their FDR. We also assessed the predictive value of features of the clinical history, including chronic inflammatory back pain (CIBP) and acute anterior uveitis (AAU), among the FDR and how they can be used to improve classification and diagnosis of axSpA.

Methods

In 1985, we studied 363 AS probands and 806 FDR who underwent rheumatologic examination, completed questionnaires, provided blood samples for HLA-typing and underwent radiography of sacroiliac joints. At follow-up in 2018–2019, 125 patients and 360 FDR were available for study, and completed a postal questionnaire about axSpA features. FDRs were asked to report whether after 1985 they had been diagnosed by Swiss rheumatologists as having axSpA.

Results

Among HLA-B27(+) FDR, axSpA occurred in 25.4%–26.3%, independent of the radiographic sacroiliitis status of the proband. AAU occurred in 13/34 (38.2%) FDR with axSpA vs 29/251 (11.6%) FDR without axSpA (p=0.00004, OR=4.74 95% CI 2.15 to 10.47). The presence of CIBP at baseline did not predict later occurrence of axSpA but combining CIBP and pain/discomfort at the thoracic spine and at anterior (ventral) chest wall ever, assessed at follow-up in 2018–2019, provided 83.1% sensitivity and 87.2% specificity for current axSpA.

Conclusion

Occurrence of AAU among FDR of axSpA probands should prompt screening for axSpA. Moreover, co-occurrence of CIBP and pain/discomfort in the thoracic spine and at anterior chest wall as a three-question tool may further enhance clinical suspicion of axSpA among these FDR.

[Socio-professional aspects of ankylosing spondylitis in Switzerland]

In this study, using a questionnaire, data were collected about the disease, the working conditions and problems, the working ability, the unemployment and the invalidity of 1134 patients suffering from ankylosing spondylitis (Bechterew's disease). In 739 cases (65.2%) a statistical evaluation could be made. 62.2% had pain when working; the reasons were most often the long working time, the position at work, and the climatic factors at the workplace. The solutions to working problems were often applied too late or they did not correspond to the needs of the patients with ankylosing spondylitis. Generally the working ability was with 97.3% high and the invalidity with 2.7% low.

[Swiss Bechterew's Disease Association: a patient self-help organization]

Ankylosing spondylitis (AS) is the third most common form of rheumatism and as such of considerable economic and social significance due to its early outbreak, its course of flare-ups and its remissions, chronic persistence and risk of early invalidity. As there is no basic therapy, the main emphasis of modern treatment lies on the practice of regular and intensive AS-specific physical exercise, complemented by suitable sports. In these circumstances, the active cooperation of the patients themselves is of utmost importance; therefore, it was obvious that the information of AS patients on their disease and their interest to improve their physical and psychological situation would be further encouraged by the foundation of a self-assistance organization for AS patients, thereby lightening the blow fate had dealt them. The Swiss Ankylosing Spondylitis Association (Schweizerische Vereinigung Morbus Bechterew, SVMB, Société de la spondylarthrite ankylosante, SSSA, Società svizzera morbo di Bechterew, SSMB), founded in 1978, has its headquarters in Zurich (Röntgenstrasse 22, CH-8005 Zurich, Tel. 01 272 78 66) and strives for the following: --the organization of local and regional therapy groups for AS gymnastics and sports --information for patients and their families on all aspects concerning AS --preparation of 'contact' meetings between AS patients to exchange experiences and thoughts --information for doctors on the latest developments in the field of AS and about the activities of the AS Society --promotion of research in the field of AS and its related diseases --information to the general population about the physical aspects of AS and the problems confronting AS patients --cooperation with other AS societies within the framework of the Ankylosing Spondylitis International Federation, ASIF.