GCCCD Investigating Associations of Exposures and Disease Questions
Part I.
To investigate the association between Kawasaki syndrome (KS) and carpet shampoo, investigators conducted a case-control study with 100 cases (100 children with KS and 100 controls (100 children without KS). Among children with KS, 50 gave a history of recent exposure to carpet shampoo. Among those without KS, 25 gave a history of recent exposure to carpet shampoo.
- What is the proportion of children exposed to carpet shampoo among cases?
- What is the proportion of children exposed to carpet shampoo among controls?
- Calculate the odds ratio for this study. How do you interpret this odds ratio?
Part II.
To study the possible association between hormone replacement therapy (HRT) and Osteoarthritis (OA) an investigator conducted a case control study using 100 women with a confirmed diagnosis of OA as cases and 200 women undergoing treatment at the same medical facility for other musculoskeletal conditions as controls with the following results. All women were 45 years or older.
OA Cases OA Controls
HRT use 60 80
HRT use 60 80
Calculate and interpret the odds ratio for this study.
Part III.
In a study similar to that described in 2 above, cases and controls were matched with respect to patient age (<65 years/65+ years) using 200 pair-wise matches with the following results:
Results describe the number of pairs in each cell
Controls with HRT use Controls No HRT
Cases with HRT use 20 40
Cases No HRT 50 90
Controls with HRT use Controls no HRT
Cases with HRT use 20 40
Cases without HRT 50 90
Calculate and interpret the odds ratio for this study.
How do you explain the differences in the results described in #2 vs. #3?