Case－control
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Example of case-control study
case-control study • A study in which the risk factors of people with a disease are compared with those without a disease. It is an epidemiological method that begins by identifying persons with the disease or condition of interest (the cases) and compares their past history of exposure to identified or suspected risk factors with the past history of similar exposures among persons who resemble the cases but do not have the disease or condition of interest (the controls). • The relationship of an attribute to the disease can therefore be examined by comparing affected and nonaffected individuals with regard to the frequency or levels of the attribute in each group.
BMJ ：喝热茶烫茶增加患喉癌风险 • • • • •
•
3 月 26 日刊登在《英国医学杂志》 (British Medical Journal) 的研究 报告指出，相较于惯喝温茶的人，喝滚烫茶水的人更容易罹患喉癌。 抽烟和酗酒特别容易引起食道癌，然而，也许因为热饮伤害喉咙组织 ，因此也被视为罹癌的好发因素之一。 为了了解更多，伊朗研究人员前往全球罹患食道癌比例最高的格列斯 坦省 (Golestan Province) 进行调查。 伊朗北部的格列斯坦省居民惯喝大量热红茶，通常每人每天喝超过 1 公升，但抽烟喝酒的人口却很低。 由德黑兰医疗科学大学 (Tehran University of Medical Sciences) 消化 系统疾病研究中心 (Digestive Disease Research Center) 人员马里克 沙迪 (Reza Malekzadeh) 领军的项目小组，将 300 名喉癌病患与 571 名住在同区的健康民众进行比对研究。 他们发现，这些喝 ( 水温介于摄氏 65-69 度 ) 热茶的人，罹患癌症的 风险比喝 ( 水温低于摄氏 65 度 ) 温茶的人高 2 倍。喝 ( 水温起码摄氏 70 度 ) 非常烫茶水的人，罹癌风险比喝温茶的人高出 8 倍。（生物谷 Bioon.com ）
• Tea drinking habits and oesophageal cancer in a high risk area in northern Iran: population based case-control study
• Objective ： To investigate the association between tea drinking habits in Golestan province, northern Iran, and risk of oesophageal squamous cell carcinoma. • Design Population based case-control study. In addition, patterns of tea drinking and temperature at which tea was drunk were measured among healthy participants in a cohort study.
• Setting Golestan province, northern Iran, an area with a high incidence of oesophageal squamous cell carcinoma. • Participants 300 histologically proved cases of oesophageal squamous cell carcinoma and 571 matched neighbourhood controls in the case-control study and 48 582 participants in the cohort study.
• Main outcome measure Odds ratio of oesophageal squamous cell carcinoma associated with drinking hot tea. • Results Nearly all (98%) of the cohort participants drank black tea regularly, with a mean volume consumed of over one litre a day. 39.0% of participants drank their tea at temperatures less than 60°C, 38.9% at 60-64°C, and 22.0% at 65°C or higher. A moderate agreement was found between reported tea drinking temperature and actual temperature measurements (weighted 0.49). The results of the case-control study showed that compared with drinking lukewarm or warm tea, drinking hot tea (odds ratio 2.07, 95% confidence interval 1.28 to 3.35) or very hot tea (8.16, 3.93 to 16.9) was associated with an increased risk of oesophageal cancer. Likewise, compared with drinking tea four or more minutes after being poured, drinking tea 2-3 minutes after pouring (2.49, 1.62 to 3.83) or less than two minutes after pouring (5.41, 2.63 to 11.1) was associated with a significantly increased risk. A strong agreement was found between responses to the questions on temperature at which tea was drunk and interval from tea being poured to being drunk (weighted 0.68).
Conclusion • Drinking hot tea, a habit common in Golestan province, was strongly associated with a higher risk of oesophageal cancer.
• Childhood Soy Intake and Breast Cancer Risk in Asian American Women
Introduction • Historically, breast cancer incidence has been substantially higher in the United States than in Asia. When Asian women migrate to the United States, their breast cancer risk increases over several generations and approaches that for U.S. Whites. Thus, modifiable factors, such as diet, may be responsible.
Methods • In this population-based case-control study of breast cancer among women of Chinese, Japanese, and Filipino descent, ages 20 to 55 years, and living in San Francisco-Oakland (California), Los Angeles (California) and Oahu (Hawaii), we interviewed 597 cases (70% of those eligible) and 966 controls (75%) about adolescent and adult diet and cultural practices. For subjects with mothers living in the United States (39% of participants), we interviewed mothers of 99 cases (43% of eligible) and 156 controls (40%) about the daughter's childhood exposures. Seventy-three percent of study participants were premenopausal at diagnosis.
Results • Comparing highest with lowest tertiles, the multivariate relative risks (95% confidence interval) for childhood, adolescent, and adult soy intake were 0.40 (0.18-0.83; Ptrend = 0.03), 0.80 (0.59-1.08; Ptrend = 0.12), and 0.76 (0.56-1.02; Ptrend = 0.04), respectively. Inverse associations with childhood intake were noted in all three races, all three study sites, and women born in Asia and the United States. Adjustment for measures of westernization attenuated the associations with adolescent and adult soy intake but did not affect the inverse relationship with childhood soy intake.
Discussion • Soy intake during childhood, adolescence, and adult life was associated with decreased breast cancer risk, with the strongest, most consistent effect for childhood intake. Soy may be a hormonally related, early-life exposure that influences breast cancer incidence.
case-control study • A study in which the risk factors of people with a disease are compared with those without a disease. It is an epidemiological method that begins by identifying persons with the disease or condition of interest (the cases) and compares their past history of exposure to identified or suspected risk factors with the past history of similar exposures among persons who resemble the cases but do not have the disease or condition of interest (the controls). • The relationship of an attribute to the disease can therefore be examined by comparing affected and nonaffected individuals with regard to the frequency or levels of the attribute in each group.
BMJ ：喝热茶烫茶增加患喉癌风险 • • • • •
•
3 月 26 日刊登在《英国医学杂志》 (British Medical Journal) 的研究 报告指出，相较于惯喝温茶的人，喝滚烫茶水的人更容易罹患喉癌。 抽烟和酗酒特别容易引起食道癌，然而，也许因为热饮伤害喉咙组织 ，因此也被视为罹癌的好发因素之一。 为了了解更多，伊朗研究人员前往全球罹患食道癌比例最高的格列斯 坦省 (Golestan Province) 进行调查。 伊朗北部的格列斯坦省居民惯喝大量热红茶，通常每人每天喝超过 1 公升，但抽烟喝酒的人口却很低。 由德黑兰医疗科学大学 (Tehran University of Medical Sciences) 消化 系统疾病研究中心 (Digestive Disease Research Center) 人员马里克 沙迪 (Reza Malekzadeh) 领军的项目小组，将 300 名喉癌病患与 571 名住在同区的健康民众进行比对研究。 他们发现，这些喝 ( 水温介于摄氏 65-69 度 ) 热茶的人，罹患癌症的 风险比喝 ( 水温低于摄氏 65 度 ) 温茶的人高 2 倍。喝 ( 水温起码摄氏 70 度 ) 非常烫茶水的人，罹癌风险比喝温茶的人高出 8 倍。（生物谷 Bioon.com ）
• Tea drinking habits and oesophageal cancer in a high risk area in northern Iran: population based case-control study
• Objective ： To investigate the association between tea drinking habits in Golestan province, northern Iran, and risk of oesophageal squamous cell carcinoma. • Design Population based case-control study. In addition, patterns of tea drinking and temperature at which tea was drunk were measured among healthy participants in a cohort study.
• Setting Golestan province, northern Iran, an area with a high incidence of oesophageal squamous cell carcinoma. • Participants 300 histologically proved cases of oesophageal squamous cell carcinoma and 571 matched neighbourhood controls in the case-control study and 48 582 participants in the cohort study.
• Main outcome measure Odds ratio of oesophageal squamous cell carcinoma associated with drinking hot tea. • Results Nearly all (98%) of the cohort participants drank black tea regularly, with a mean volume consumed of over one litre a day. 39.0% of participants drank their tea at temperatures less than 60°C, 38.9% at 60-64°C, and 22.0% at 65°C or higher. A moderate agreement was found between reported tea drinking temperature and actual temperature measurements (weighted 0.49). The results of the case-control study showed that compared with drinking lukewarm or warm tea, drinking hot tea (odds ratio 2.07, 95% confidence interval 1.28 to 3.35) or very hot tea (8.16, 3.93 to 16.9) was associated with an increased risk of oesophageal cancer. Likewise, compared with drinking tea four or more minutes after being poured, drinking tea 2-3 minutes after pouring (2.49, 1.62 to 3.83) or less than two minutes after pouring (5.41, 2.63 to 11.1) was associated with a significantly increased risk. A strong agreement was found between responses to the questions on temperature at which tea was drunk and interval from tea being poured to being drunk (weighted 0.68).
Conclusion • Drinking hot tea, a habit common in Golestan province, was strongly associated with a higher risk of oesophageal cancer.
• Childhood Soy Intake and Breast Cancer Risk in Asian American Women
Introduction • Historically, breast cancer incidence has been substantially higher in the United States than in Asia. When Asian women migrate to the United States, their breast cancer risk increases over several generations and approaches that for U.S. Whites. Thus, modifiable factors, such as diet, may be responsible.
Methods • In this population-based case-control study of breast cancer among women of Chinese, Japanese, and Filipino descent, ages 20 to 55 years, and living in San Francisco-Oakland (California), Los Angeles (California) and Oahu (Hawaii), we interviewed 597 cases (70% of those eligible) and 966 controls (75%) about adolescent and adult diet and cultural practices. For subjects with mothers living in the United States (39% of participants), we interviewed mothers of 99 cases (43% of eligible) and 156 controls (40%) about the daughter's childhood exposures. Seventy-three percent of study participants were premenopausal at diagnosis.
Results • Comparing highest with lowest tertiles, the multivariate relative risks (95% confidence interval) for childhood, adolescent, and adult soy intake were 0.40 (0.18-0.83; Ptrend = 0.03), 0.80 (0.59-1.08; Ptrend = 0.12), and 0.76 (0.56-1.02; Ptrend = 0.04), respectively. Inverse associations with childhood intake were noted in all three races, all three study sites, and women born in Asia and the United States. Adjustment for measures of westernization attenuated the associations with adolescent and adult soy intake but did not affect the inverse relationship with childhood soy intake.
Discussion • Soy intake during childhood, adolescence, and adult life was associated with decreased breast cancer risk, with the strongest, most consistent effect for childhood intake. Soy may be a hormonally related, early-life exposure that influences breast cancer incidence.
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