An odds ratio less than 1 in a multivariate logistic regression indicates what about the exposure and outcome?

• A. Increased odds
• B. Decreased odds
• C. No association
• D. Confounded association

Answer: (B)

In multivariate logistic regression, the odds ratio shows how the odds of the outcome change with the exposure after accounting for other variables in the model. An odds ratio below 1 means the exposure is associated with lower odds of the outcome, indicating a protective or inverse relationship when other factors are held constant. For example, an odds ratio of 0.6 implies the odds of the outcome are 40% lower with the exposure than without, after adjustment. If the odds ratio were above 1, the exposure would be linked to higher odds of the outcome; if it were around 1, there would be little or no association. The fact that it is less than 1 reflects the direction of association under adjustment, not a claim of causation.