Long-term prognosis and causes of death after spondylodiscitis: A Danish nationwide cohort study

Abstract

Background: Data on long-term prognosis after spondylodiscitis are scarce. The purpose of this study was to determine long-term mortality and the causes of death after spondylodiscitis. Methods: A nationwide, population-based cohort study using national registries of patients diagnosed with non-post-operative pyogenic spondylodiscitis from 1994–2009, alive 1 year after diagnosis (n = 1505). A comparison cohort from the background population individually matched for sex and age was identified (n = 7525). Kaplan-Meier survival curves were constructed and Poisson regression analyses used to estimate mortality rate ratios (MRR). Results: Three hundred and sixty-five patients (24%) and 1115 individuals from the comparison cohort (15%) died. Unadjusted MRR for spondylodiscitis patients was 1.76 (95% CI = 1.57–1.98) and 1.47 (95% CI = 1.30–1.66) after adjustment for comorbidity. No deaths were observed in 128 patients under the age of 16 years. Siblings of patients did not have increased long-term mortality compared with siblings of the individuals from the comparison cohort. This study observed increased mortality due to infections (MRR = 2.57), neoplasms (MRR = 1.40), endocrine (MRR = 3.72), cardiovascular (MRR = 1.62), respiratory (MRR = 1.71), gastrointestinal (MRR = 3.35), musculoskeletal (MRR = 5.39) and genitourinary diseases (MRR = 3.37), but also due to trauma, poisoning and external causes (MRR = 2.78), alcohol abuse-related diseases (MRR = 5.59) and drug abuse-related diseases (6 vs 0 deaths, MRR not calculable). Conclusions: Patients diagnosed with spondylodiscitis have increased long-term mortality, mainly due to comorbidities, particularly substance abuse.