Background/Purpose: The prevalence of Ankylosing Spondylitis (AS) in Europe has been estimated in a number of studies, some based on clinic populations, others from general population surveys, and prevalence has been shown to range between 9 and 49/10,000.  However, to date, none have attempted to determine the prevalence in primary and secondary care within the same population.  Knowing, not only the prevalence, but also the proportion of patients managed in specialist services has important implications in terms of health service planning and resource allocation.  Thus, the aim of the current study was (a) to determine, in a single population, the prevalence of AS plus the proportion of patients actively managed in secondary care; and (b) to examine differences in basic characteristics of these patients.

Methods: Data from the Primary Care Clinical Informatics Unit (PCCIU) and the Scotland Registry for Ankylosing Spondylitis (SIRAS) were utilised to estimate the prevalence of AS in Scotland, in primary and secondary care respectively.

Established in April 2000, and covering around a third of the entire population, the PCCIU collected data from a representative sample of general practices across Scotland, UK, via Read Codes: a coded thesaurus of clinical terms used to document all diseases (including AS).  SIRAS is a registry collecting clinical and patient-reported outcomes on all patients with a clinical diagnosis of AS being seen within secondary care clinics in Scotland.  Patients were identified via clinic lists, if available, or through a review of recent physician correspondence for evidence of an AS diagnosis.

Data for the denominator was taken either from the PCCIU database (total patients) or the mid-year population estimate for Scotland, published by the National Records of Scotland.

Results: In April 2007, the PCCIU comprised 1,469,688 persons, of whom 1,964 had received a diagnostic code for AS (prevalence: 13.4 per 10,000; 95%CI 12.8-14.0 per 10,000).  The SIRAS registry identified 1,686 patients in secondary care; from a population of 3,578,984 (prevalence: 4.7 per 10,000; 4.5-4.9 per 10,000).

There was no difference in sex between the two populations, although patients managed in secondary care were more likely to be younger (mean age 51 vs 62yrs; p<0.001), received their diagnosis earlier (mean age 35 vs 38yrs; p<0.001) and were more likely to experience extra-spinal manifestations of disease (uveitis 34% vs 22%, inflammatory bowel disease 12% vs 6% and psoriasis 14% vs 6%; all p<0.001).

Conclusion: As far as we are aware, this is the first study to estimate the prevalence of AS simultaneously in primary and secondary care, in the same population.  We have shown that nearly two-thirds of AS patients in Scotland are managed solely in primary care, without rheumatology input.  This group are less likely to have extra-spinal manifestations, but are older with a longer time since diagnosis.  This, not only has important ramifications in terms of health service resource planning, but highlights the importance, in a progressive disease, of ascertaining whether some of these individuals have serious spinal pathology that is currently inadequately managed.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/only-one-third-of-patients-with-spondyloarthritis-are-managed-by-rheumatologists/