Parental Rheumatoid Arthritis, Child Mortality, and Case Fatality: A Nationwide Cohort Study.

Objective: We have previously reported increased long-term morbidity in children of parents with rheumatoid arthritis (RA). Here we assess child mortality and case fatality in the same cohort.

Methods: All singletons born in Denmark from 1977 to 2008 were identified through linkage of Danish national registries. Cox proportional hazards models were used to calculate hazard ratios (HRs) of death from all causes among children exposed to parental RA, compared to unexposed children. Risk of death after infection or respiratory diseases was also assessed for children below the age of 5 years.

Results: This study followed 1,917,723 newborns for an average of 16 years. Of these, 13,556 were exposed to maternal RA and 6,330 to paternal RA. Overall mortality rates in children exposed to maternal or paternal RA did not differ from those in unexposed children (HR 0.98 [95% confidence interval (95% CI) 0.84-1.15] and 1.08 [95% CI 0.86-1.36], respectively), nor did the risk of death below the ages of 5 years, 3 years, or 1 year. In the group of children below the age of 5 years, 6,106 children of parents with RA were diagnosed with respiratory diseases and 3,320 with infectious diseases. The case fatality rate in children with these diseases was not significantly higher than in unexposed children (HR 1.11 [95% CI 0.74-1.66] and 0.84 [95% CI 0.52-1.35], respectively).

Conclusion: Children of parents with RA had similar mortality rates as other children, as well as after diagnoses of respiratory or infectious diseases.