Asthma and all-cause mortality in children and young adults: A population-based study

Background Studies suggest an increased all-cause mortality among adults with asthma. We aimed to study the relationship between asthma in children and young adults and all-cause mortality, and investigate differences in mortality rate by also having a life-limiting condition (LLC) or by parental socioeconomic status (SES). Methods Included in this register-based study are 2 775 430 individuals born in Sweden between January 1986 and December 2012. We identified asthma cases using the National Patient Register (NPR) and the Prescribed Drug Register. Those with LLC were identified using the NPR. Parental SES at birth (income and education) was retrieved from Statistics Sweden. We estimated the association between asthma and all-cause mortality using a Cox proportional hazards regression model. Effect modification by LLC or parental SES was studied using interaction terms in the adjusted model. Results The adjusted hazard rate (adjHR) for all-cause mortality in asthma cases versus non-asthma cases was 1.46 (95% CI 1.33 to 1.62). The highest increased rate appeared to be for those aged 5-15 years. In persons with asthma and without LLC, the adjHR remained increased at 1.33 (95% CI 1.18 to 1.50), but differed (p=0.002) from those with asthma and LLC, with an adjHR of 1.87 (95% CI 1.57 to 2.22). Parental SES did not alter the association (income, p=0.55; education, p=0.83). Conclusion This study shows that asthma is associated with an increased mortality in children and young adults regardless of LLC or parental SES. Further research is warranted to investigate the possible mechanisms for this association

Asthma and subsequent school performance at age 15–16 years: A Swedish population-based sibling control study

Asthma may negatively affect children’s school performance, such as grades and exam results. Results from previous studies have shown varying results and may have suffered from confounding and other biases. We used a Swedish population-based cohort of 570,595 children with data on asthma (including severity and control) in Grades 7–8 and 9, school performance from Grade 9 (grade point sum, non-eligibility for upper secondary school and national test results) and measured confounders from national registers. We used sibling comparisons to account for unmeasured familial factors. Children with asthma and severe asthma performed slightly better in school than children without asthma when adjusting for measured confounders, but the associations were attenuated in sibling comparisons. In contrast, children with uncontrolled asthma performed slightly worse (e.g. Grade 9: βadj = −9.9; 95% CI −12.8 to −7.0; Cohen’s d = 0.16). This association remained for uncontrolled asthma in Grade 9 in sibling comparisons (Grade 9: β = −7.7 points; 95% CI −12.6 to −2.6; Cohen’s d = 0.12), but not for Grades 7–8. The attenuation of estimates when controlling for familial factors using sibling comparisons suggests that the differences were due to familial factors, rather than being causal. The remaining associations in sibling comparisons between uncontrolled asthma in Grade 9 and school performance are consistent with a causal association