title: The epidemiology of ankylosing spondylitis and the commencement of anti-TNF therapy in daily rheumatology practice.
abstract: OBJECTIVE
  This study aimed to describe the epidemiology of ankylosing spondylitis (AS) in rheumatology practice at the beginning of the anti-TNF (tumour necrosis factor) era, and to evaluate the initiation of anti-TNF therapy in a clinical setting where prescription is regulated by the authority's imposed reimbursement criteria.
  
  
  METHODS
  Between February 2004 and February 2005, all Belgian rheumatologists in academic and non-academic outpatient settings were invited to register all AS patients who visited their practice. A random sample of these patients was further examined by an in-depth clinical profile. In a follow-up investigation, we recorded whether patients initiated anti-TNF therapy and compared this to their eligibility at baseline evaluation.
  
  
  RESULTS
  89 rheumatologists participated and registered 2141 patients; 1023 patients were clinically evaluated. These 847 fulfilled the New York modified criteria for definite AS and 176 for probable AS. The profile of AS in rheumatology practice is characterised by longstanding and active disease with a high frequency of extra-articular manifestations and metrological and functional impairment. At a median of 2 months after the clinical evaluation, anti-TNF therapy was initiated in 263 of 603 (44%) evaluable patients with definite AS and in 22 of 138 (16%) evaluable patients with probable AS (total 38%). More than 85% of the patients who started anti-TNF therapy had an increased Bath Ankylosing Spondylitis Disease Activity Index despite previous NSAID (non-steroidal anti-inflammatory drug) use.
  
  
  CONCLUSIONS
  Of a representative cohort of 1023 Belgian AS patients seen in daily rheumatology practice, about 40% commenced anti-TNF therapy. Decision factors to start anti-TNF therapy may include disease activity and severity.
authors.affiliation: Rheumatology Department, Ghent University Hospital, De Pintelaan 185, 90000 Ghent, Belgium. Bert.VanderCruyssen@Ugent.be
authors.forename: Bert
authors.initials: B
authors.lastname: Vander Cruyssen
authors.forename: Clio
authors.initials: C
authors.lastname: Ribbens
authors.forename: Annelies
authors.initials: A
authors.lastname: Boonen
authors.forename: Herman
authors.initials: H
authors.lastname: Mielants
authors.forename: Kurt
authors.initials: K
authors.lastname: de Vlam
authors.forename: Jan
authors.initials: J
authors.lastname: Lenaerts
authors.forename: Serge
authors.initials: S
authors.lastname: Steinfeld
authors.forename: Filip
authors.initials: F
authors.lastname: Van den Bosch
authors.forename: Lode
authors.initials: L
authors.lastname: Dewulf
authors.forename: Nathan
authors.initials: N
authors.lastname: Vastesaeger
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000191:economics / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000191:economics / Q000627:therapeutic use*; D001530:Belgium / Q000453:epidemiology; D015331:Cohort Studies; D016527:Drug Costs; D000068800:Etanercept; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D007074:Immunoglobulin G / Q000191:economics / Q000627:therapeutic use; D000069285:Infliximab; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010818:Practice Patterns, Physicians'; D018124:Receptors, Tumor Necrosis Factor / Q000627:therapeutic use; D012042:Registries; D012219:Rheumatology; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000188:drug therapy / Q000453:epidemiology*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
chemical_list: D000911:Antibodies, Monoclonal; D018501:Antirheumatic Agents; D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D000069285:Infliximab; D000068800:Etanercept