The association of family history of herpes zoster and the risk of incident herpes zoster: the SHEZ Study

BACKGROUND: We investigated whether family histories of herpes zoster (HZ) are associated with the risk of incident HZ in a Japanese population. METHODS: A total of 12,522 Japanese residents aged ≥50 years in Shozu County participated in the baseline survey between December 2008 and November 2009 (the participation rate = 72.3%). They were interviewed at baseline by research physicians regarding the registrants’ history of HZ. A self-administered questionnaire survey was conducted to evaluate the potential confounding factors. 10,530 participants without a history of HZ were followed up to ascertain the incidence of HZ during 3-years follow-up until the end of November 2012 with Japanese nationals. We estimated hazard ratios (HRs) of incident HZ according to first-degree family histories using the Cox proportional hazard regression after adjusting for age, sex, and other potential confounding factors. RESULTS: Compared to no HZ history of each family member, a history of brother or sister was associated with a higher risk of incident HZ while histories of father and mother were not. The multivariable HR (95%CI) of incident HZ for a history of brother or sister was 1.67 (1.04–2.69). When comparing to no family histories of all first-degree relatives, the multivariable HRs (95%CIs) were 1.34 (0.77–2.34) for a history of brother or sister alone, but 4.81 (1.78–13.00) for a history of mother plus brother or sister. As for the number of family histories, the multivariable HRs (95%CIs) were 1.08 (0.76–1.54) for one relative (father, mother, or brother or sister) and 2.75 (1.13–6.70) for two or more relatives. CONCLUSION: Family histories of mother plus brother or sister and two or more first-degree relatives were associated with a higher risk of incident HZ.