Appeasing the wheezing : determinants and outcomes of respiratory disease in childhood

Sammanfattning: The aim of this thesis was to study the determinants and outcomes asthma and cystic fibrosis in childhood by using study populations of persons born in Sweden and data from a clinical cohort and national health and demographic registers and a quality register. In Paper I and Paper II we explored determinants of respiratory disease. In Paper I we studied if there was association between maternal asthma, allergic asthma, and lung function during pregnancy and childhood asthma and growth using a clinical cohort of mothers and their children born from 2012 to 2017, retrieved from the MAESTRO (Maternal Asthma Events, Stress and Offspring) and MAESTRO-Child studies. Results showed that higher lung function values in the mother was associated with a lowered risk of childhood asthma. Further, there was no statistically significant association between maternal asthma/maternal allergic asthma/lung function during pregnancy and childhood growth. In Paper II we studied the relationship between parental socioeconomic status (SES, education and income) measured at birth and at five years and childhood asthma using data from national registers and a cohort born from 2001 to 2013. We found that parental education and income at birth was associated with childhood asthma with onset under one year of age and that only parental education at birth was associated with an increased risk of childhood asthma with onset over one year of age. When this was studied in a cousin-comparison we found that the association between parental education persisted, implying that confounding by shared factors in the family do not fully account for the association between SES and asthma Finally low parental SES measured at five years was associated with an increased risk of asthma at five years. In Paper III and Paper IV, we explored the outcomes of respiratory disease. In Paper III we investigated the association between asthma and all-cause mortality in children and young adults born from 1986 to 2012 using data from national registers. Asthma was associated with an increase in all-cause mortality and the highest mortality rate was for children aged five to 15 years with asthma. The estimates remained increased when this association between asthma and all- cause mortality was studied in a sub-group analysis of children born from 2000. Further, the estimates differed depending on if the person also had a life-limiting condition, but not on parental SES at birth. In Paper IV we studied the association between parental SES (measured at birth and at five years) and severe disease, lung function and growth in persons with cystic fibrosis born 1973 to 2019 using a cohort from the Swedish Cystic Fibrosis Register and data from the Swedish Cystic Fibrosis Register and national registers We found some evidence that parental SES measured at birth and at five years was associated with severe disease and increased lung function decline, however there was no statistically significant relationship between low parental SES and growth decline. In conclusion factors associated with respiratory disease in childhood include maternal asthma, maternal lung function and parental SES. Asthma is associated with all-cause mortality, where comorbidity but not parental SES play an import role.