Spinal fractures in patients with versus without ankylosing spinal disorders: a nationwide propensity score-matched study on survival and health-related quality of life.

Objective: The evidence on ankylosing spinal disorders (ASDs), including ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH), in the context of spinal fracture stems from studies with relatively small sample sizes. There are no studies addressing the patient-reported outcome measures (PROMs) and health-related quality of life (HRQOL) outcomes associated with spinal fracture in this population. The aim of this study was to investigate differences in complications, mortality, PROMs, and HRQOL in patients with and without ASD who had been treated for spinal fracture.

Methods: This is a nationwide multicenter retrospective study of prospectively collected data from the Swedish Fracture Register. All patients with fractures of the cervical, thoracic, or lumbar spine treated surgically and conservatively between January 2015 and December 2021 were eligible for inclusion. Two groups of patients were formed based on the presence or absence of concomitant ASD. Primary outcomes of interest included death and PROMs. For surgically treated patients, data on complications and reoperation rates were retrieved. Propensity score matching with a ratio of 1:1 was used to balance the groups prior to intergroup comparison. Variables included in the matching process were age, sex, mechanism of injury, neurological function on admission (Frankel grade), injury type (high vs low energy), fracture type, injured spinal level, time to treatment, and type of treatment (surgical vs conservative). Kaplan-Meier analyses were used to study overall survival following injury.

Results: A total of 14,604 patients without ASD and 1368 patients with ASD were included in this study. High-energy injuries were less frequent in patients with ASD (13% vs 24%, p < 0.001). Moreover, patients with ASD were less likely to be neurologically intact on admission (90% vs 94%, p < 0.001). There were 1707 surgically treated patients without ASD and 559 with the disorder. After matching, a higher overall risk of reoperation was found among patients with ASD (9.1% vs 3.4%, p = 0.007). Surgical site infections requiring reoperation (p = 0.012), but not construct failure or CSF leakage requiring reoperation (p ≥ 0.05), were more common among the patients with ASD. Postmatching, there were no differences in overall survival between ASD and non-ASD cases (p > 0.05). Moreover, patients with and without ASD had similar PROMs, as indicated by the EQ-5D-3L index at 1 year after injury (p = 0.59).

Conclusions: Self-reported recovery 1 year after spinal fracture occurred to a similar extent in patients with and without ASD. Moreover, ASD alone was not a significant risk factor for death. Finally, surgically treated patients with ASD experienced higher rates of postoperative complications and reoperations following surgery.