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.