PMC:4137988 / 23755-25446 JSONTXT

{"project":"2_test","denotations":[{"id":"25143747-22712878-55576557","span":{"begin":363,"end":365},"obj":"22712878"},{"id":"25143747-17947786-55576558","span":{"begin":1374,"end":1376},"obj":"17947786"}],"text":"Second, the heterogeneity of reported results is also possibly attributable to the varied number of confounders controlled for in the studies. For example, the number of confounders controlled for ranged from five to 19 in the observational studies among adults. Confounding could pose challenges for interpretation of the diet–asthma relationship. Nurmatov et al59 have proposed a comprehensive list of primary and secondary confounders that should be considered in future epidemiologic studies examining the early-life diet and asthma relationship in children. The authors suggested that the primary confounders should account for maternal and child characteristics, socioeconomic status, environmental exposures, and dietary factors, while the secondary confounders could be confirmed using appropriate statistical tests. Confounders in the diet–asthma relationship are different between children and adults; therefore, further research is needed to investigate confounders in the adult population. Future observational studies should select confounders based on existing knowledge of the causal mechanism in the diet– asthma relationship and suggestive evidence from statistical analysis. The criteria for selection of confounders should also be reported in observational studies, so readers can be well informed to reach a valid and reliable interpretation of findings.60 In addition, very few population-based studies have been conducted to investigate the association between dietary patterns and asthma outcomes. National survey data (eg, the National Health and Nutrition Examination Survey) may be leveraged to examine the diet–asthma association and identify potential covariates."}