Background context: Several reports indicate that patients with ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) have increased mortality after cervical spine fractures. However, outcomes of the fractured hyperostotic cervical spine are incompletely described, and there are limited data regarding the covariable effects of patient age and medical comorbidities on mortality.
Purpose: To determine mortality associated with cervical fractures in patients with hyperostotic disease.
Study design: Retrospective case-control study.
Patient sample: Forty-three patients identified through a registry as having fractures of the cervical spine in the setting of hyperostotic disease. These patients were matched to 43 controls who did not carry the diagnosis of hyperostotic disease.
Outcome measures: Mortality at 3 months and 1, 2, and 3 years after fracture.
Methods: An institutional database was used to identify all cervical fractures sustained by patients aged 65 years and older from 1991 to 2006. Demographic information, date of injury, associated injuries, treatment type, presence of AS or DISH, and comorbidities were abstracted from medical records and radiographs. Mortality was ascertained using the National Death Index. Patients with AS or DISH were matched to controls who did not carry the diagnosis of hyperostotic disease. Risks of mortality were calculated at 3 months, 1 year, 2 years, and 3 years. Kaplan-Meier methods, logistic regression analysis, the two independent sample t test, and the Fisher exact test were used to compare mortalities between the two groups. Statistical significance was determined as p values <.05.
Results: Forty-three patients were identified as having fractures in the setting of hyperostotic disease of the cervical spine. Twenty-seven individuals had DISH, and 16 had AS. The average age of both the study group and controls was 80 years, with an age range of 68 to 94. There was no significantly increased risk of mortality between the overall study group and control group at 3 months (p=.20), 1 (p=.22), 2 (p=.15), or 3 years (p=.50) after injury. Compared with controls, subgroup analysis of patients with AS showed a statistically increased risk of mortality at 3 months (p<.01) and at 1 and 2 years (p<.01 at both time points). When compared with individuals with DISH, those with AS had an increased risk of mortality at time points up to 2 years after fracture. Patients with DISH did not have an increased mortality risk at any time point when compared with controls.
Conclusions: The effect of fracture on mortality appears to be greatest in those with AS. Patients with DISH did not demonstrate an increased risk of mortality compared with age- and sex-matched controls. Future studies of patients with hyperostotic disease should analyze patients with DISH and AS separately instead of as a single homogenous group.
Level of evidence: Level IV.
Published by Elsevier Inc.