Background Although TNF-alpha inhibitors by easing pain and restoring function have revolutionized the treatment of patients with ankylosing spondylitis (AS), so far no certain influence on the development of spinal ankylosis has been documented, and it remains to be shown whether TNF-alpha inhibition influences joint destruction and subsequent need for arthroplasty surgery. Consequently, the aim of treatment in AS is still to reduce clinical symptoms.
Objectives We wished to investigate whether improved treatment has resulted in a diminishing use of arthroplasty surgery.
Methods Nearly all patients (98%) having undergone an arthroplasty of the hip later than 1987 are registered in the Norwegian Arthroplasty Register (NAR). Data concerning the identity of the patient, diagnosis and date of surgery are among the information recorded. We selected the group of patients having received a hip prosthesis on the basis of AS in the years 1988-2010 (n=534, 73.8% men), and compared the trend in number of procedures being performed annually with the time trend of the same procedure in patients with osteoarthritis (OA) (n=95094, 31.6% men). For statistical analysis we used Poisson regression models to test for the trend, and change in trend over the years. A random effect was included in the model to account for overdispersion in the data.
Results The frequency of hip prosthesis surgery in both groups increased steadily up until 2002, with a coefficient of 0.028 per year for OA patients (p<0.001), and a coefficient of 0.039 per year for AS patients (p=0.002). Whereas the number of surgical procedures in the OA group continued to rise significantly (p<0.001) with a coefficient of 0.017 per year in the years 2003-2010, there was a trend towards a reduced frequency of hip prosthesis surgery (coefficient of minus 0.022 per year) in the AS group, although the reduction was not statistically significant (p=0.51).
Conclusions The present study’s major finding was a trend of reduced frequency of hip replacement procedures in patients with AS during the time span 2003-2010 which contrasts the continued increase for OA patients. Up until 2002 the frequency increased significantly in accordance with the general increase in joint replacement surgery. TNF-alpha inhibition was introduced in the treatment of Norwegian AS patients in 2000, and our findings suggest that this medication may alter the prognosis of these patients by reducing large joint arthritis and thus reducing the need for hip replacement surgery.
Disclosure of Interest None Declared
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