Estimating the contribution of individual risk factors to disease in a person with more than one risk factor

Received 13 March 2001; received in revised form 24 September 2001; accepted 4 November 2001.

Abstract

Various measures have been proposed to express the excess risk of an outcome attributable to one particular risk factor, such as attributable risk and risk fraction. However, there is sometimes a need, both in epidemiological studies and in awarding compensation in legal cases, to simultaneously consider the contribution of several risk factors to a disease outcome, when a biological model is not available. We propose a method that allocates the proportional contribution of several risk factors to a disease outcome, based on the weighted contribution of the risk fraction for each risk factor. We demonstrate the use of this method using figures for renal cell carcinoma, and discuss the caveats in using this method for epidemiologic studies, and in awarding compensation in legal cases.

Keywords: Risk assessment, Risk factors, Epidemiologic methods, Causality, Renal cell carcinoma

a Evidence for Population Health Unit, The University of Manchester, Manchester M13 9PT, UK

b The Centre for Clinical Epidemiology and Biostatistics, University of Newcastle, Newcastle, 2300 NSW, Australia

c Behavioural Science in Relation to Medicine, School of Population Health Sciences, University of Newcastle, Newcastle 2308 NSW, Australia

Corresponding author. Tel.+44(0)161-275-5953; fax: +44-(0)161-275-7712.(P. McElduff)

PII: S0895-4356(02)00388-8

6 of 21