Information for questions 5-6: Investigators measured body mass index (BMI) on a
ID: 3359472 • Letter: I
Question
Information for questions 5-6: Investigators measured body mass index (BMI) on all adults who had sigmoidoscopy at Parkhurst Community Hospital in 1987. These patients were classified as having or not having adenomatous colorectal polyps based on the result of the examination. In patients with BMI <24.0 kg/m2, 39 patients had such polyps and 153 did not. In patients with BMI 24.0 kg/m2, 24 patients had such polyps and 147 did not.
Construct a 2 x 2 table and calculate the odds (odds ratio) of adenomatous colorectal polyps associated with body mass index (BMI) < 24.0 kg/m2. The group with BMI > 24.0 kg/m2 is the reference group.
Explanation / Answer
Result:
Information for questions 5-6: Investigators measured body mass index (BMI) on all adults who had sigmoidoscopy at Parkhurst Community Hospital in 1987. These patients were classified as having or not having adenomatous colorectal polyps based on the result of the examination. In patients with BMI <24.0 kg/m2, 39 patients had such polyps and 153 did not. In patients with BMI ³ 24.0 kg/m2, 24 patients had such polyps and 147 did not.
Construct a 2 x 2 table and calculate the odds (odds ratio) of adenomatous colorectal polyps associated with body mass index (BMI) < 24.0 kg/m2. The group with BMI > 24.0 kg/m2 is the reference group.
BMI <24.0
BMI ³ 24.0
Total
polyps
39
24
63
no polyps
153
147
300
Total
192
171
363
Odds ratio = (39*147)/(153*24) = 1.56127451
=1.5613
BMI <24.0
BMI ³ 24.0
Total
polyps
39
24
63
no polyps
153
147
300
Total
192
171
363