Question

1. Identify the study design.Which is the main exposure variable and which is the outcome variable? 2. A confounder is an extraneous variable that wholly or partially accounts for the observed effect of a risk factor on disease status. It should meet all of the following three conditions: . it is an independent risk factor for the outcome. . it is associated with the exposure . it is not in the causal pathway between exposure and outcome One way to deal with confounding is to adjust for (or control for) the confounding variables in statistical analysis by including them in the model. Was confounding addressed in the current study? If so, which variables were considered confounders? (Hint: Refer to Table 1 and Table 2 for the risk factors that were also included in the statistical model which tested the association between post-menopausal estrogen therapy and heart discase).

Answer 1

1. The longitudinal study design was used in this study where the postmenopausal women are observed and followed-up for a period of 10 years of time. Exposure variable is also called an independent variable or explanatory variable. It is a variable which can be changed and the effects are measured by researchers. In this study, estrogen therapy is the main exposure variable and the researcher measured the effects of estrogen therapy and the risk of cardiovascular disease. An outcome variable is also called the dependent variable. It is a predictor variable that affects the independent variable. Age, Lifestyle pattern, type and duration of estrogen therapy are the dependent variables which increase or decreases the risk of cardiovascular disease.

2. A confounder is a third variable which influences changes in both the dependent and independent variable. The participants who were under estrogen therapy must also consume alcohol or smoking cigarettes which affect the results of the study. Cigarette smoking and alcohol consumption are considered an independent risk factor for cardiovascular disease and is associated with the exposure and outcome of variables. In this study, diabetes, cigarette smoking, hypertension, hypercholesterolemia are considered as confounders and risk are analyzed.