EPI 202 Lab 3 Practice Problem Solutions - Epi 202 Lab 3...

Epi 202 Lab 3: Practice Problem Proposed Solutions
The data from an incidence density-sampled case-control study of the association between
caffeine intake and Parkinson’s disease is below. The exposure of interest is caffeine intake (high
vs. low), and the outcome is Parkinson’s disease. Cases were appropriately matched to controls
(1:1 matching) by age and smoking status.
Pair # Case exposure Control
exposure
Pair # Case exposure Control exposure
1 + - 11 + -
2 + + 12 - -
3 - + 13 - +
4 - - 14 - +
5 - + 15 - -
6 + - 16 + -
7 - - 17 - +
8 - + 18 - +
9 - + 19 + +
10 + + 20 + -
1. Make a 2x2 table for the matched case-control data
Exposed controls Non-exposed controls
Exposed cases 3 5
Non-exposed cases 8 4
2. Calculate and interpret the odds ratio for the association of coffee intake (high vs. low) and
Parkinson’s disease, accounting for the matching factors.
= 5/8

= 0.625
The odds of Parkinson’s disease for individuals with high caffeine intake is 0.625 times the odds
of Parkinson’s disease for individuals with low caffeine intake, after accounting for the matching
factors (smoking status and age), assuming no residual confounding by smoking status and age,
no other unmeasured confounding, no selection bias, and no information bias.
3. Test whether there is an association between caffeine intake (high vs. low) and the incidence
of Parkinson’s disease after accounting for the matching factors. State your hypotheses.