Premature Adult Death in Individuals Born Preterm: A Sibling Comparison in a Prospective Nationwide Follow-Up Study

• Published in: PloS one Vol. 11; no. 11; p. e0165051
• Main Authors: Risnes, Kari R, Pape, Kristine, Bjørngaard, Johan H, Moster, Dag, Bracken, Michael B, Romundstad, Pal R
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.11.2016; Public Library of Science (PLoS)
• Subjects: Adolescent; Adults; Age; Analysis; Biology and Life Sciences; Birth; Cancer; Cardiovascular disease; Cardiovascular diseases; Cohort analysis; Cohort Studies; Confidence intervals; Death; Drug abuse; Environmental factors; Epidemiology; Fatalities; Female; Follow-Up Studies; Genetic diversity; Gestation; Gestational age; Health aspects; Health risk assessment; Heart diseases; Humans; Male; Medicine and Health Sciences; Mental health; Middle Aged; Mortality; Mortality, Premature; Overdose; People and Places; Population studies; Premature Birth; Prospective Studies; Research and Analysis Methods; Siblings; Socioeconomic factors; Studies; Young Adult; Norway
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0165051

Close to one in ten individuals worldwide is born preterm, and it is important to understand patterns of long-term health and mortality in this group. This study assesses the relationship between gestational age at birth and early adult mortality both in a nationwide population and within sibships. The study adds to existing knowledge by addressing selected causes of death and by assessing the role of genetic and environmental factors shared by siblings. Study population was all Norwegian men and women born from 1967 to 1997 followed using nation-wide registry linkage for mortality through 2011 when they were between 15 and 45 years of age. Analyses were performed within maternal sibships to reduce variation in unobserved genetic and environmental factors shared by siblings. Specific outcomes were all-cause mortality and mortality from cardiovascular diseases, cancer and external causes including accidents, suicides and drug abuse/overdoses. Compared with a sibling born in week 37-41, preterm siblings born before 34 weeks gestation had 50% increased mortality from all causes (adjusted Hazard Ratio (aHR) 1.54, 95% confidence interval (CI) 1.17, 2.03). The corresponding estimate for the entire population was 1.27 (95% CI 1.09, 1.47). The majority of deaths (65%) were from external causes and the corresponding risk estimates for these deaths were 1.52 (95% CI 1.08, 2.14) in the sibships and 1.20 (95% CI 1.01, 1.43) in the population. Preterm birth before week 34 was associated with increased mortality between 15 and 45 years of age. The results suggest that increased premature adult mortality in this group is related to external causes of death and that the increased risks are unlikely to be explained by factors shared by siblings.