2.1.1.2. Data analysis and interpretation: making associations between exposure and disease in cross-sectional studies

When cross-sectional studies collect information on disease prevalence and simultaneous exposure to factors that may contribute to disease, Odds Ratios (ORs) can be used to calculate the degree of association between concurrent exposure and disease state. We can calculate the odds of exposure among cases compared to the odds of exposure among non-cases (controls). The OR is the odds of exposure in an individual who was diseased divided by the odds of exposure in an individual who was disease free.

Equation 2.1.1.2.a

Where a,b,c,d are defined by the Table 2. The Confidence Intervals for Odds Ratio can be calculated using Equation 2.1.1.2 b.

Equation 2.1.1.2.b

Table 2. Structure of data for calculation of odds ratio.

Table 2