Statistical analysis
SPSS v. 22 (IBM SPSS Statistics, IBM Corporation, Chicago, IL, USA) was used for data analysis. Descriptive analysis for continuous variables was performed. Categorical variables were displayed as absolute numbers and percentages. Median survival age was the primary outcome,19 assessed by the Kaplan-Meier analysis; groups were compared with the log-rank test. Duration of survival was defined as the time between the date of birth and date of death, or the last follow-up. Median age at death was calculated for all individuals in the cohort. Influence of risk factors was assessed by a uni- and multivariate Cox regression model, with 95% confidence intervals (CI). A P value < 0.05 was considered significant.