Exposure to different residential indoor characteristics during childhood and asthma in adolescence: a latent class analysis of the Danish National Birth Cohort

Abstract

Background: Many residential indoor environments may have an impact on children's respiratory health.

Objectives: The aims of this study were to identify latent classes of children from the Danish National Birth Cohort (DNBC) who share similar patterns of exposure to indoor home characteristics, and to examine the association between membership in the latent classes and asthma in adolescence.

Methods: We included data on residential indoor characteristics of offspring from the DNBC whose mothers had responded to the child's 11-year follow-up and who had data on asthma from the 18-year follow-up. Number of classes and associations were estimated using latent class analysis. To account for sample selection, we applied inverse probability weighting.

Results: Our final model included five latent classes. The probability of current asthma at 18 years was highest among individuals in class one with higher clustering on household dampness (9, 95%CI 0.06-0.13). Individuals in class four (with higher clustering on pets ownership and living in a farm) had a lower risk of current asthma at age 18 compared to individuals in class one (with higher clustering on household dampness) (OR 0.53 (95%CI 0.32-0.88), p = .01).

Conclusion: Our findings suggest that, in a high-income country such as Denmark, groups of adolescents growing up in homes with mold and moisture during mid-childhood might be at increased risk of current asthma at age 18. Adolescents who grew-up in a farmhouse and who were exposed to pets seem less likely to suffer from asthma by age 18.

Keywords: Asthma; Danish National Birth Cohort; Environmental epidemiology; Home characteristics; Indoor air pollution.

Fig. 1

Flowchart of the invited and participating populations in the 11-year & 18-year data collections of the Danish National Birth Cohort a Individuals who have not withdrawn their consent as of December 2021. b The latest available update from registers was in 2015 when most DNBC children had not yet turned 18 years old c The invitation was mailed by postal service to the parent(s) for whom the child had residential address d One parent could answer more than one questionnaire if more than one of their children was enrolled in the DNBC  e Four individuals were excluded due to very small missing values f Number of parental questionnaires returned and completed, 98.3% filled out by the biological mother, 1.2% by the biological father, 0.1% by others (none biological father or mother, grandparents)  and 0.4 unknown  g Includes 3383 individuals excluded due to returning incomplete questionnaires

Fig. 2

Elbow plot of information criteria values for all latent class analysis models

Fig. 3

Heat map of the distribution of residential indoor characteristics (item response probabilities) by latent class of 10,329 children participating in the 11-year and 18-year follow-ups of the DNBC