prev next front |1 |2 |3 |4 |5 |6 |7 |8 |9 |10 |11 |12 |13 |14 |15 |16 |17 |18 |19 |20 |21 |22 |23 |24 |review
An example of a case-control study investigating blood alcohol concentration and the risk of fatal pedestrial injury is shown here. The research question underlying the study design is, "How do exposures to alcohol among cases compare with the exposures to alcohol in the population?"

The table shows with numbers and percentages the simplest way to express the difference in exposure between cases and controls. The controls in this study were chosen by selecting pedestrians similar in age and gender to the cases. The controls were also similar to the cases in that they were walking near the same intersection in Manhattan, and at the same time of day as the cases were when they were struck by a motor vehicle.

The data show a clear association between blood alcohol concentration and fatal pedestrian injury. One may collapse the categories above and say that the odds of a fatal injury are about four times higher with 50 mg% or more BAC compared with a BAC of less than 50 mg%, with a 95% confidence interval of 1.5 to 12.8.

prev next front |1 |2 |3 |4 |5 |6 |7 |8 |9 |10 |11 |12 |13 |14 |15 |16 |17 |18 |19 |20 |21 |22 |23 |24 |review