Familial risks of hospital treated spinal stenosis in first-, second-, and third-degree relatives: A nationwide family study

Background Context Spinal stenosis (SS) has a multifactorial background. Purpose This nationwide study aimed to determine the familial risks of hospital treated SS in first-, second-, and third-degree relatives in Sweden. Study Design The Swedish Multigeneration register was linked to the National Patient Register to investigate the heredity of hospital treated SS between 1997 and 2018. Patient Sample Offspring born to Swedish-born parents were included. Outcome Measures Familial hazard ratios (HRs) for SS were calculated for relatives of individuals who had a diagnosis of SS compared with relatives of individuals unaffected by SS as the reference group. The adjusted familial hazard ratios (afHRs) with 95% confidence interval (CI) were determined for SS among pairs of twins, full-siblings, half-siblings, and cousins. Methods Adjustments were made for birth year, sex, education, occupation, and comorbidities including amyloidosis. Results A total of 6,548,565 individuals (48.77% women) were included with a mean age of 41 years (range 0-87 years) at the end of follow-up. 36,958 (0.56%) individuals were affected with hospital treated SS. The afHR for SS were for twins 5.12 (95%CI 3.33-7.89), siblings 2.47 (95%CI 2.35-2.60), half-siblings 1.49 (95%CI 1.28–1.73), and cousins 1.10 (95%CI 0.85–1.43). Among full siblings, afHRs were 5.38 (95%CI 2.02-14.33) for cervical SS and 3.01 (95%CI 2.69-3.67) for lumbar SS. A total of 0.27% SS patients had amyloidosis. Patients with amyloidosis had an adjusted HR of 2.03 (95%CI 1.67 - 2.48) for SS. Conclusions Heredity is associated with higher risk of hospital treated SS in the Swedish population.