What factors are associated with the prevalence of atopic symptoms amongst adolescents in Greater Manchester?

Exposure to Domestic Abuse and the Subsequent Development of Atopic Disease in Women

BACKGROUND

Exposure to domestic violence and abuse (DVA) is a global public health issue associated with substantial morbidity and mortality. There are few high-quality studies that assess the impact of DVA exposure on the development of atopic disease.

OBJECTIVE

To examine the association between exposure to DVA and the subsequent development of atopy.

METHODS

In this population-based, retrospective, open cohort study, we identified women with no history of atopic disease between January 1, 1995 and September 30, 2019 from IQVIA Medical Research Data, an anonymized UK primary care dataset. We used clinical codes to identify exposed patients (those with a code identifying exposure to DVA; n = 13,852) and unexposed patients (n = 49,036), who were matched by age and deprivation quintile. Cox proportional hazards regression was used to calculate hazard ratios (HRs) (with 95% CIs) of developing atopic disease: asthma, atopic eczema, or allergic rhinoconjunctivitis.

RESULTS

During the study period, 967 exposed women (incidence rate, 20.10/1,000 person-years) developed atopic disease, compared with 2,607 unexposed women (incidence rate, 13.24/1,000 person-years). This translated to an adjusted HR of 1.52 (95% CI, 1.41-1.64) accounting for key confounders; asthma (adjusted HR = 1.69; 95% CI, 1.44-1.99), atopic eczema (adjusted HR = 1.40; 95% CI, 1.26-1.56), and allergic rhinoconjunctivitis (adjusted HR = 1.63; 95% CI, 1.45-1.84).

CONCLUSIONS

Domestic violence and abuse is a significant global public health issue. These results demonstrate a significant associated risk for developing atopic disease. Public health approaches to the prevention and detection of DVA are necessary to reduce the associated ill health burden.

Pollen exposure at birth and adolescent lung function, and modification by residential greenness

BACKGROUND

Exposure to high levels of pollen in infancy is a risk factor for allergic respiratory diseases in later childhood, but effects on lung function are not fully understood. We aim to examine associations between grass pollen exposure in the first months of life and lung function at 12 and 18 years, and explore potential modification.

METHODS

Using the Melbourne Atopy Cohort Study, a birth cohort of children with a family history of allergic diseases, we modeled the association between cumulative grass pollen exposure up to 3 months after birth, on FEV₁ , FVC, and FEV₁ /FVC ratio at 12 and 18 years. We also assessed modifying effects of residential greenness levels (derived from satellite imagery), asthma, and early life sensitization to ryegrass.

RESULTS

Grass pollen exposure in the first 7 days was associated with a reduction in FEV₁ (-15.5 mL; 95% CI: -27.6, -3.3 per doubling of pollen count) and FVC (-20.8 mL; -35.4, -6.1) at 12 years, but not at 18 years. Increase in cumulative grass pollen exposure up to 3 months was negatively associated with FVC at 12 and 18. Exposure to high residential greenness modified the association at 18 years.

CONCLUSION

Early exposure to grass pollen was associated with decreased lung function in children and adolescents. Targeted interventions for pollen avoidance strategies that take into account local topography could be implemented alongside other clinical interventions such as immunotherapy.

Estimating the causal effect of body mass index on hay fever, asthma and lung function using Mendelian randomization

BACKGROUND

Observational studies have shown that body mass index (BMI) is positively associated with asthma. However, observational data are prone to confounding and reverse causation. In Mendelian randomization, genetic variants are used as unconfounded markers of exposures to examine causal effects. We examined the causal effect of BMI on asthma, hay fever, allergic sensitization, serum total immunoglobulin E (IgE), forced expiratory volume in one-second (FEV1) and forced vital capacity (FVC).

METHODS

We included 490 497 participants in the observational and 162 124 participants in the genetic analyses. A genetic risk score (GRS) was created using 26 BMI-associated single nucleotide polymorphisms (SNPs). Results were pooled in meta-analyses and expressed as odds ratios (ORs) or β-estimates with 95% confidence interval (CI).

RESULTS

The GRS was significantly associated with asthma (OR=1.009; 95% CI: 1.004, 1.013), but not with hay fever (OR= 0.998; 95% CI: 0.994, 1.002) or allergic sensitization (OR=0.999; 95% CI: 0.986, 1.012) per BMI-increasing allele. The GRS was significantly associated with decrease in FEV1: β=-0.0012 (95% CI: -0.0019, -0.0006) and FVC: β=-0.0022 (95% CI: -0.0031, -0.0014) per BMI-increasing allele. Effect sizes estimated by instrumental variable analyses were OR=1.07 (95% CI: 1.03, 1.10) for asthma, a 9 ml decrease in FEV1 (95% CI: 2.0-15 mL decrease) and a 16 ml decrease in FVC (95% CI: 7.0-24 mL decrease) per 1 kg/m² higher BMI.

CONCLUSIONS

The results support the conclusion that increasing BMI is causally related to higher prevalence of asthma and decreased lung function, but not with hay fever or biomarkers of allergy.