Ankylosing spondylitis (AS) is associated with increased spinal fracture risk due to loss of elasticity in spinal motion segments. With the introduction of biological disease modifying anti-rheumatic drugs (bDMARD) treatment for AS patients the individual course of the disease has been decelerated. This study aims to clarify whether the improved medical therapy reduced the spinal fracture incidence.
Included were all patients with the diagnosis of AS 1987 to 2014 from the Swedish Patient Registry. From the Swedish Prescribed Drug Registry the Anatomical Therapeutic Chemical codes for bDMARD, non-steroidal anti-inflammatory drugs (NSAID), methotrexate (MTX) and sulfasalazine were extracted and numbers of prescriptions and years of treatment counted since 2005.
12297 patients with ankylosing spondylitis were included between 1987 and 2014 (age 67±19, 67% male). Of these 291 had spinal fractures between 2011 and 2014. The number of prescriptions of bDMARD increased during the last decade, but not of MTX, sulfasalazine and NSAID. 64% of all AS patients used NSAID, 13% used bDMARD, 13% used MTX, and 10% used sulfasalazine. A multivariate analysis of patients with spinal fractures 2011-2014 found bDMARD delaying spinal fracture debut by 1.24 years per year of bDMARD treatment (p=0.028). The use of bDMARD had no significant effect on spinal fracture risk (OR=0.93, 95%-C.I.=0.85-1.01, p=0.09).
This study failed to demonstrate a beneficial effect on spinal fracture risk for AS patients treated with bDMARD during the last decade. Still bDMARD treatment delayed spinal fracture occurrence, which is promising with regard to results from future studies.
ClinicalTrials.gov, Identifier NCT02840695.