Mini Oral Australian Epidemiology Association ASM 2018

Vertebral fractures and Ankylosing Spondylitis patients in Western Australia. (#93)

Milica Ognjenovic 1 , Warren Raymond 1 , Charles Inderjeeth 2 , Helen Keen 3 , David Preen 1 , Johannes Nossent 1 2
  1. The Univeristy of Western Australia, Crawley, WA, Australia
  2. Department of Rheumatology, Sir Charles Gairdner Hospital, Perth, WA, Australia
  3. Department of Rheumatology, Fiona Stanley Hospital, Perth, WA, Australia

Background

Ankylosing Spondylitis (AS) causes spinal osteoporosis and rigidity leading to increased risk of vertebral fractures. Large scale studies on vertebral fractures in AS patients are scarce, particularly in the southern hemisphere, with rates reported between 0.4% and 32%.

Aim

Longitudinally investigate population wide spinal fracture rates in AS patients and compare the prevalence, disease burden and survival rates between AS and AS-free controls. 

Methods

Whole-population observational case-control study analysed data extracted between 1980 and 2015, from the Western Australian Linkage System. AS patients were identified using International Classification of Diseases, 9th (720) and Australian 10th (M45, M08) revision. AS patients were matched with up to 5 controls for age, gender, Indigenous status and event date. Kaplan-Meier was used to estimate survival rates and conditional cox regression for age-gender adjusted hazard ratios.

Results

We identified 1285 AS patients (70% males, average 70 ±14.65 years) and 6177 controls, followed up for a median of 21 years. Vertebral fractures occurred in 91 (7%) AS patients and 135 (2%) controls, unadjusted OR: 3.41 (95%CI: 2.60, 4.48), remaining stable after stratified by decade. Life expectancy following first vertebral fracture event was 5 years shorter for AS-patients than controls at 10, 20 and 30 years with 45% vs 65%, 22% vs. 50% and 20% vs. 45%, respectively, P < 0.001 (age-gender adjusted HR = 1.54, 95%CI: 1.08, 2.20).

Conclusion

Vertebral fractures remain significantly more frequent in AS patients than controls in the anti-TNF era, and lead to a 5-years shortened lifespan.