Shared and Nonshared Familial Susceptibility to Surgically Treated Inguinal Hernia, Femoral Hernia, Incisional Hernia, Epigastric Hernia, and Umbilical Hernia

BACKGROUND: The familial risk of abdominal wall hernia (AWH) is largely unknown. In addition, it is unknown whether inguinal hernia (IH), femoral hernia (FH), incisional hernia (INH), epigastric hernia (EH), and umbilical hernia (UH) share familial susceptibility. The aim of this nationwide study was to determine the familial risks of concordant AWH (same disease in proband and exposed relative) and discordant AWH (different disease in proband and exposed relative). STUDY DESIGN: Data from the Swedish Multigeneration Register on individuals aged 0 to 78 years were linked to the Swedish hospital discharge register and the Swedish outpatient register for the period from 1964 to 2010. Standardized incidence ratios (SIRs) and 95% CIs for surgically treated IH (n = 209,814 cases), FH (n = 4,576), INH (n = 19,494), EH (n = 8,257), and UH (n = 22,761) were calculated for siblings of individuals with hernia compared with the siblings of unaffected individuals. The procedure was repeated for spouses. RESULTS: All concordant and most discordant familial sibling risks were increased. Familial concordant SIRs for siblings were IH = 1.97 (95% CI, 1.94-1.99), FH = 3.40 (95% CI, 2.44-4.62), INH = 2.24 (95% CI, 2.04-2.46), EH = 5.57 (95% CI, 4.64-6.64), and UH = 3.61 (95% CI, 3.33-3.91). Concordant familial risks were higher than discordant risks. For example, when the proband sibling had IH, the discordant SIRs were FH = 1.74 (95% CI, 1.61-1.88), INH = 1.22 (95% CI, 1.16-1.28), EH = 1.30 (95% CI, 1.20-1.40), and UH = 1.35 (95% CI, 1.29-1.41). Concordant SIRs for spouses were lower: IH = 1.23 (95% CI, 1.20-1.26), FH = 0.97 (95% CI, 0.64-1.36), INH = 1.56 (95% CI, 1.41-1.71), EH = 1.70 (95% CI, 1.09-2.45), and UH = 1.31 (95% CI, 1.09-1.56). CONCLUSIONS: Family history of surgically treated AWH is an important risk factor for surgical treatment of AWH. The 5 forms of AWH studied share familial susceptibility, but site-specific familial factors might exist. Several spouse risks were increased, suggesting the possibility of a nongenetic contribution to familial risks. (C) 2013 by the American College of Surgeons