TY - JOUR

T1 - Weighing the Causal Pies in Case-Control Studies

AU - Liao, Shu Fen

AU - Lee, Wen Chung

N1 - Funding Information:
This study is supported by the National Science Council, Taiwan, Republic of China .

PY - 2010/7

Y1 - 2010/7

N2 - Purpose: Epidemiologists are familiar with the concepts of Rothman's causal pies. Using real data the Hoffman study showed recently how to calculate the " proportion of diseased subjects who develop the disease due to classes of sufficient causes" (PDCs). The PDC is actually an attributable-fraction index. It may be specific to a particular risk factor profile but it does not correspond to any given class of causal pies. In this study, we show how to estimate the " causal-pie weights" (CPWs), so that each and every class of causal pies has one and only one CPW attached to it. Methods: To conform to Rothman's model, we apply a non-negative linear odds model to constrain all the odds ratios (ORs) to be equal to or greater than one, and the interactions between them to be additive or superadditive. Based on these constrained ORs, we calculate the population attributable fractions, and then the CPWs. We used a published case-control data to show the methodology. Results: The CPWs succinctly quantify the relative importance of different classes of causal pies. Conclusions: The proposed method helps to clarify the multi-factorial and complex interactive effects in disease causation. It also provides important information for designing an efficient public health intervention strategy.

AB - Purpose: Epidemiologists are familiar with the concepts of Rothman's causal pies. Using real data the Hoffman study showed recently how to calculate the " proportion of diseased subjects who develop the disease due to classes of sufficient causes" (PDCs). The PDC is actually an attributable-fraction index. It may be specific to a particular risk factor profile but it does not correspond to any given class of causal pies. In this study, we show how to estimate the " causal-pie weights" (CPWs), so that each and every class of causal pies has one and only one CPW attached to it. Methods: To conform to Rothman's model, we apply a non-negative linear odds model to constrain all the odds ratios (ORs) to be equal to or greater than one, and the interactions between them to be additive or superadditive. Based on these constrained ORs, we calculate the population attributable fractions, and then the CPWs. We used a published case-control data to show the methodology. Results: The CPWs succinctly quantify the relative importance of different classes of causal pies. Conclusions: The proposed method helps to clarify the multi-factorial and complex interactive effects in disease causation. It also provides important information for designing an efficient public health intervention strategy.

UR - http://www.scopus.com/inward/record.url?scp=77953560683&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77953560683&partnerID=8YFLogxK

U2 - 10.1016/j.annepidem.2010.04.003

DO - 10.1016/j.annepidem.2010.04.003

M3 - Article

C2 - 20538201

AN - SCOPUS:77953560683

VL - 20

SP - 568

EP - 573

JO - Annals of Epidemiology

JF - Annals of Epidemiology

SN - 1047-2797

IS - 7

ER -