The Dietary Inflammatory Index and asthma burden in children: A latent class analysis

Introduction: Unbalanced dietary intake has been increasingly recognized as an important modifiable risk factor for asthma. In this study, we assessed whether a pro-inflammatory diet is associated with higher asthma burden in three steps: (1) identification of asthma latent classes (LC) based on symptoms, indoor exposures, and pulmonary function; (2) identification of risk factors associated with LC membership; and (3) estimation of the probabilities of LC membership with variation in DII. Methods: A cross-sectional study on 415 children aged 5-14 years (266 with persistent asthma and 149 controls). LC analysis was performed in asthmatic children. The DII was calculated based on a semiquantitative food frequency questionnaire. Elastic net logistic regression was used to investigate whether increasing DII was associated with worse asthma burden. Results: Two LCs were identified. Children in Class 1, "high burden," had higher symptom burden and worse lung function. Children in Class 2, "low burden," had lower symptom burden and less impaired lung function but were more subject to indoor exposures. DII was the only risk factor significantly associated with Class 1 membership. As the DII increased (from -4.0 to +4.0), the probability of Class 1 membership increased from 32% to 65% when compared with control group, whereas it increased from 41% to 72% when compared with Class 2. Conclusions: We identified two phenotypes of persistent asthma associated with different disease burden linked to indoor exposures. An increasing DII was associated with high-burden asthma, providing further evidence about the role of a pro-inflammatory diet in asthma morbidity.