Background/Purpose: Approximately 30% of HLA-B27(+) patients with ankylosing spondylitis (AS) have one or more episodes of acute anterior uveitis (AAU), a condition that is also seen in HLA-B27(+) individuals without AS. We sought to investigate whether the occurrence of AAU is linked primarily to AS rather than to HLA-B27 allele.

Methods: In 1985 members of the Swiss AS Patient Society who had been diagnosed as having AS by their own physicians, as well as their first degree relatives, were invited to participate in the current study. After obtaining ethical approval and informed consent, 1178 subjects, 363 of them probands, formed our study cohort.  They completed questionnaires on disease manifestations, underwent rheumatological examination of axial and peripheral joints, and provided blood samples for genetic studies, including HLA-B27. Probands also provided a recent pelvic radiograph to document presence of sacroiliitis. If their pelvic radiograph was not available, it was performed on-site. Relatives aged ≥18 years underwent pelvic radiography, unless pregnant. Pelvic radiographs were available for 360 probands and 713 relatives. Radiographs were blindly assessed twice by each of 4 readers. The assessment could only be performed once for 164 (46%) of the 360 radiographs of the probands (only available a few hours). The sacroiliitis score for each sacroiliac (SI) joint ranged from 0 (normal) to 4 (ankylosis). Scores were added and then divided by the number of assessments. Scores below bilateral grade 2.0 or grade 3.0 unilaterally were considered not meeting New York (NY) radiographic criteria. 

In 2018 the ethical committee of the Swiss Kanton of Bern approved the follow up study. Many Swiss city and village administrations provided current addresses of former participants and reported the year of death of 182 deceased persons, including 123 AS probands. A total of 462 consenting participants completed a 157 item postal disease related questionnaire that included questions addressing AAU-related symptoms (Table 1). We compared the responses (to our questions suggestive of AAU) by the 85 HLA-B27(+) AS patients meeting the NY radiographic criteria for sacroiliitis with those of the 130 unaffected (“healthy”) HLA-B27(-) relatives, and also the responses of the 111 unaffected (“healthy”) HLA-B27(+) relatives with those of the 130 HLA-B27(-) “healthy” relatives. Scores were compared by chi-square testing and likelihood ratio analysis.

Results: Eye symptoms that suggested previous occurrence(s) of AAU episode(s) were reported significantly more often by the 85 HLA-B27(+) AS patients fulfilling the NY radiographic criteria than by the 130 HLA-B27(-) relatives (of the HLA-B27(+) AS probands) (Table). Interestingly, we found no differences in responses suggestive of AAU episodes between HLA-B27(+) and HLA-B27(-) relatives.

Conclusion: It should be noted that our questionnaire has not yet been validated. However, although one cannot exclude selection or detection bias (for AS patients), the results support the view that HLA-B27(+) AAU is more closely related to the disease AS/axSpA than to the HLA-B27 allele itself.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/is-the-occurrence-of-acute-anterior-uveitis-linked-primarily-to-ankylosing-spondylitis-as-or-to-hla-b27-results-of-a-35-year-follow-up-family-study-of-a-swiss-cohort-of-patients-with-as/