Incidence and predictors of morphometric vertebral fractures in patients with ankylosing spondylitis

Abstract

IntroductionAnkylosing spondylitis (AS) is associated with an increased incidence of vertebral fractures (VFs); however the actual incidence and predictors of morphometric VFs are unknown. The present study examined the incidence and predictors of new VFs in a large AS cohort.MethodsIn total, 298 AS patients who fulfilled the modified New York criteria were enrolled and spinal radiographs were evaluated biennially. Clinical and laboratory data and radiographic progression were assessed according to the Bath AS Disease Activity Index, erythrocyte sedimentation rate, C-reactive protein (CRP), and the Stoke AS spine score (SASSS). VF was defined according to the Genant criteria. The incidence of VFs at 2 and 4 years was evaluated using the Kaplan-Meier method. The age-specific standardized prevalence ratio (SPR) for AS patients in comparison with the general population was calculated.ResultsOf 298 patients, 31 (10.8%) had previous VFs at baseline. A total of 30 new VFs occurred in 26 patients over 4 years. The incidence of morphometric VFs was 4.7% at 2 years and 13.6% at 4 years. Multivariate logistic regression analysis showed that previous VFs at baseline and increased CRP levels at 2 years were predictors of new VFs (odds ratio (OR) =12.8, 95% confidence interval (CI) = 3.6-45.3 and OR = 5.4, 95% CI = 1.4–15.9). The age-specific specific standardized prevalence ratio of morphometric VFs in AS was 3.3 (95% CI 2.1–4.5).ConclusionsThe incidence of morphometric VFs increased in AS. Previous VFs and increased CRP levels predicted future VFs. Further studies are needed to identify the effects of treatment interventions on the prevention of new VFs.

Assessment of fracture risk in patients with axial spondyloarthritis: a case–control study using the fifth Korean National Health and Nutrition Examination Survey (KNHANES V)

“…Low BMD at the femoral neck in patients with axSpA contributed to a higher FRAX score, suggesting that the increase in fracture risk in patients with axSpA may be associated with bone loss induced by systemic inflammation rather than by known risk factors. Previous studies show that bone loss and inflammation are associated with vertebral fractures in AS (9,25,26).…”

“…Second, we only included clinical or self-reported fractures in our assessment of fracture history, as we were unable to investigate morphometric vertebral fractures. Although most of these fractures are asymptomatic, they occur more frequently in axSpA patients than in controls (9), so the FRAX score may underestimate the risk of morphometric vertebral fractures in axSpA patients. In addition, when selecting matched controls from KNHANES V, we excluded subjects taking prescription medications.…”

“…In recent population-based cohort studies, AS has been associated with an increased risk of vertebral and non-vertebral clinical fractures (7,8). In a previous study we showed that the prevalence of morphometric vertebral fractures is also higher in AS patients than in healthy controls (9). Despite the increased prevalence of fractures associated with AS, no studies have compared the fracture risk between axSpA patients and the general population.…”

Clinical Risk Factors for the Presence and Development of Vertebral Fractures in Patients With Ankylosing Spondylitis

“…Two longitudinal studies reported about the incidence of radiographic vertebral fractures in AS. An observational cohort study in 298 AS patients on different treatment regimens reported an incidence rate of vertebral fractures of 5% over 2 years and 14% over 4 years in the lumbar spine only . In our previous study, which included 105 AS patients treated with tumor necrosis factor (TNF) inhibitors, we found an incidence rate of 20% over 4 years in both the lumbar and the thoracic spine .…”

“…In patients with ankylosing spondylitis (AS), characterized by chronic inflammation of the axial spine, the risk of clinical vertebral fractures is 2‐ to 8‐fold higher than in non‐AS subjects . Previous studies in AS patients evaluating radiographic vertebral fractures reported prevalence rates ranging from 10% to 43% .…”