Power Estimation and Follow-Up Period Evaluation in Korea Radiation Effect and Epidemiology Cohort Study / 예방의학회지
Journal of Preventive Medicine and Public Health
;
: 543-548, 2010.
Article
in Korean
| WPRIM
| ID: wpr-103483
ABSTRACT
OBJECTIVES:
The objective of this study was to calculate sample size and power in an ongoing cohort, Korea radiation effect and epidemiology cohort (KREEC).METHOD:
Sample size calculation was performed using PASS 2002 based on Cox regression and Poisson regression models. Person-year was calculated by using data from '1993-1997 Total cancer incidence by sex and age, Seoul' and Korean statistical informative service.RESULTS:
With the assumption of relative risk=1.3, exposurenon-exposure=12 and power=0.8, sample size calculation was 405 events based on a Cox regression model. When the relative risk was assumed to be 1.5 then number of events was 170. Based on a Poisson regression model, relative risk=1.3, exposurenon-exposure=12 and power=0.8 rendered 385 events. Relative risk of 1.5 resulted in a total of 157 events. We calculated person-years (PY) with event numbers and cancer incidence rate in the non-exposure group. Based on a Cox regression model, with relative risk=1.3, exposurenon-exposure=12 and power=0.8, 136 245PY was needed to secure the power. In a Poisson regression model, with relative risk=1.3, exposurenon-exposure=12 and power=0.8, person-year needed was 129517PY. A total of 1939 cases were identified in KREEC until December 2007.CONCLUSIONS:
A retrospective power calculation in an ongoing study might be biased by the data. Prospective power calculation should be carried out based on various assumptions prior to the study.
Full text:
Available
Index:
WPRIM (Western Pacific)
Main subject:
Risk
/
Incidence
/
Cohort Studies
/
Dose-Response Relationship, Radiation
/
Republic of Korea
/
Neoplasms, Radiation-Induced
Type of study:
Etiology study
/
Incidence study
/
Observational study
/
Prognostic study
/
Risk factors
/
Screening study
Limits:
Adolescent
/
Adult
/
Aged
/
Aged80
/
Child
/
Child, preschool
/
Female
/
Humans
/
Infant
/
Male
Country/Region as subject:
Asia
Language:
Korean
Journal:
Journal of Preventive Medicine and Public Health
Year:
2010
Type:
Article
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