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Is opium a real risk factor for esophageal cancer or just a methodological artifact? hospital and neighborhood controls in case-control studies

Shakeri, R. and Kamangar, F. and Nasrollahzadeh, D. and Nouraie, M. and Khademi, H. and Etemadi, A. and Islami, F. and Marjani, H. and Fahimi, S. and Sepehr, A. and Rahmati, A. and Abnet, C.C. and Dawsey, S.M. and Brennan, P. and Boffetta, P. and Malekzadeh, R. and Majdzadeh, R.l (2012) Is opium a real risk factor for esophageal cancer or just a methodological artifact? hospital and neighborhood controls in case-control studies. PLoS ONE, 7 (3).

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Abstract

Background: Control selection is a major challenge in epidemiologic case-control studies. The aim of our study was to evaluate using hospital versus neighborhood control groups in studying risk factors of esophageal squamous cell carcinoma (ESCC). Methodology/Principal Findings: We compared the results of two different case-control studies of ESCC conducted in the same region by a single research group. Case definition and enrollment were the same in the two studies, but control selection differed. In the first study, we selected two age- and sex-matched controls from inpatient subjects in hospitals, while for the second we selected two age- and sex-matched controls from each subject's neighborhood of residence. We used the test of heterogeneity to compare the results of the two studies. We found no significant differences in exposure data for tobacco-related variables such as cigarette smoking, chewing Nass (a tobacco product) and hookah (water pipe) usage, but the frequency of opium usage was significantly different between hospital and neighborhood controls. Consequently, the inference drawn for the association between ESCC and tobacco use did not differ between the studies, but it did for opium use. In the study using neighborhood controls, opium use was associated with a significantly increased risk of ESCC (adjusted OR 1.77, 95 CI 1.17-2.68), while in the study using hospital controls, this was not the case (OR 1.09, 95 CI 0.63-1.87). Comparing the prevalence of opium consumption in the two control groups and a cohort enrolled from the same geographic area suggested that the neighborhood controls were more representative of the study base population for this exposure. Conclusions/Significance: Hospital and neighborhood controls did not lead us to the same conclusion for a major hypothesized risk factor for ESCC in this population. Our results show that control group selection is critical in drawing appropriate conclusions in observational studies. © 2012 This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Item Type: Article
Additional Information: cited By 6
Uncontrolled Keywords: opiate; opiate, adult; aged; article; cancer risk; case control study; cigarette smoking; cohort analysis; controlled study; disease association; environment; esophageal squamous cell carcinoma; female; hospital based case control study; human; intermethod comparison; major clinical study; male; neighborhood; neighborhood based case control study; observational study; opiate addiction; patient selection; pilot study; population research; risk assessment; risk factor; smokeless tobacco; age; case control study; demography; esophagus tumor; hospital; hospital patient; Iran; methodology; middle aged; prevalence; sex difference; smoking; squamous cell carcinoma, Nicotiana tabacum, Adult; Age Factors; Aged; Carcinoma, Squamous Cell; Case-Control Studies; Esophageal Neoplasms; Female; Hospitals; Humans; Inpatients; Iran; Male; Middle Aged; Opium; Prevalence; Research Design; Residence Characteristics; Risk Factors; Sex Factors; Smoking
Subjects: کهورت
مقالات نمایه شده محققین دانشگاه در سایت ,Web of Science ,Scopus
موارد کلی
Divisions: معاونت تحقیقات و فناوری
Depositing User: GOUMS
Date Deposited: 21 Apr 2015 09:15
Last Modified: 19 May 2015 03:55
URI: http://eprints.goums.ac.ir/id/eprint/2598

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