Trends in hospitalizations for vertebral compression fracture in ankylosing spondylitis: data from the National Inpatient Sample 2000-2014.

Ankylosing spondylitis (AS) patients are at increased risk of vertebral compression fractures (VCF). Our objective was to examine the yearly trend of VCF hospitalizations in AS patients as compared to rheumatoid arthritis (RA) and the general population. National Inpatient Sample (NIS) database (2000-2014) was used to identify adult (≥ 18 years) hospitalizations, based on validated ICD-9 diagnosis codes. The rate of VCF hospitalizations, as a primary diagnosis, was assessed in three mutually exclusive groups: AS, RA, and the general population. The prevalence of VCF hospitalization was highest in AS (2.70%), compared to 0.77% in RA and 0.35% in the general population. Over the 15-year period, VCF hospitalization in AS was noted to have an increasing trend (Annual Percent Change (APC) = 4.73, p < 0.05) in contrast to the stable trend in the general population (APC = 0.34, p = NS) and a declining trend in RA (APC -3.61, p < 0.05). VCF related to AS was also associated with a longer hospital stay as compared to the general population (8.1 days vs. 5.1 days, p < 0.05) and higher inpatient mortality (3.4% vs. 1.0%, p < 0.05). A higher rate of VCF hospitalization along with an increasing trend was noted in AS as compared to RA and compared to the general population. Better screening approaches and treatment strategies for AS patients with VCF risk are urgently needed to reduce hospitalizations and related complications. Key Points • An increasing trend of VCF hospitalization was noted in AS, in contrast to a declining trend in RA and a stable trend in the general population. • VCF in AS was associated with longer hospital stay and higher inpatient mortality than in RA and the general population.