Main Studies Integrate retrospective studies, observational studies, and Mendelian randomization (MR) study methods to systematically analyze the strength and direction of the association between depression and asthma.
Explore whether a causal relationship exists between depression and asthma, and identify potential confounding factors and effect modifiers.
Secondary Studies Screen for key confounding variables that affect the association between depression and asthma (e.g., age, gender, lifestyle, comorbidities, etc.).
Analyze the correlation between depression and the severity of asthma. Verify the stability of instrumental variables (IVs) and the reliability of causal effects in the MR study.
Key Term Supplementary Explanations Effect modifiers: Factors that alter the strength or direction of the association between an exposure (e.g., depression) and an outcome (e.g., asthma) (e.g., certain genes or medications may modify how depression influences asthma risk).
Instrumental variables (IVs): Genetic variants used in MR studies that are associated with the exposure (e.g., depression-related SNPs) but not directly associated with the outcome (e.g., asthma) except through the exposure, helping to reduce confounding and infer causality.