Case-control studies: matched controls or all available controls?
In order to realize the variation in the estimate of the odds ratio from case-control studies, results from individually matched sampling were compared with those from the analysis based on a large number of controls. The subjects were selected from those who visited Aichi Cancer Center Hospital from 1988 to 1990. Cases consisted of 251 male lung cancer patients aged 40-79 years. Age and year of visit matched controls were sampled independently 100 times and 5000 times from non-cancer male outpatients (cases to controls ratio: 1:1, 1:2, 1:3, and 1:4). As unmatched controls, all male non-cancer outpatients aged 40-79 years (4100 patients) were used. The smoking habit was adopted as an exposure variable. As logically expected, analysis based on 4100 male controls gave a steadier estimate than the matched analyses examined here, indicating that a matched sampling is not recommended when a large number of controls are available.
Hamajima
N
N
Division of Epidemiology, Aichi Cancer Center Research Institute, Nagoya, Japan.
Hirose
K
K
Inoue
M
M
Takezaki
T
T
Kuroishi
T
T
Tajima
K
K
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008175:Lung Neoplasms / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012107:Research Design; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology