What is AOR Score?
AOR stands for Adjusted Odds Ratio, not a "score" - it is a statistical measure that quantifies the strength of association between an exposure and an outcome after controlling for confounding variables.
Definition and Purpose
An adjusted odds ratio (aOR or AOR) is derived from multivariable logistic regression analysis and represents the odds of an outcome occurring in an exposed group compared to an unexposed group, while statistically adjusting for other factors (confounders) that might influence this relationship 1, 2, 3.
How to Interpret AOR Values
- AOR = 1.0: No association between exposure and outcome
- AOR > 1.0: Increased odds of the outcome with exposure (positive association)
- AOR < 1.0: Decreased odds of the outcome with exposure (protective association)
For example, an aOR of 1.5 means the exposed group has 50% higher odds of the outcome compared to the unexposed group, after accounting for confounders 1.
Key Distinction: AOR vs Risk Ratio
A critical caveat: AOR approximates relative risk (RR) only when the outcome is rare (<10% incidence). When outcomes are common (≥10%), the odds ratio systematically overestimates the relative risk - the more common the outcome, the greater the overestimation 4, 5, 6, 7.
For common outcomes:
- If AOR > 1, it overestimates the true risk ratio
- If AOR < 1, it underestimates the true risk ratio
- The discrepancy increases as baseline risk increases 5
Clinical Application
When reading research that reports AOR values 1, 2, 3, 8, 9:
Check the baseline outcome rate in the control/unexposed group
If outcome is rare (<10%): AOR ≈ relative risk - interpret directly
If outcome is common (≥10%): AOR exaggerates the true effect - apply conversion formulas or interpret cautiously 4, 7
Always examine the 95% confidence interval alongside the AOR - this shows precision and whether the association is statistically significant (if CI excludes 1.0) 10
Common Pitfall
The most frequent error is interpreting AOR as relative risk when the outcome is common, leading to overestimation of clinical impact 5, 6. Always consider baseline risk when translating AOR values into clinical decision-making.