CONCEPTUAL ASPECTS OF ATTRIBUTABLE RISK WITH RECURRENT DISEASE EVENTS

The concept of attributable risk is extended to cover disease events w hich are potentially recurrent. Whereas the conventional attributable risk parameter allows quantification of the proportion of diseased ind ividuals due to a certain risk factor, the parameter introduced here q uantifies the proportion of disease events which is attributable to a specific exposure variable. We accomplish this by taking into account not only the probability of ever being affected by the disease but als o the exposure-specific number of occurrences of the disease event wit hin a defined time period. Practical examples highlighting the relevan ce of the new measure are presented. Various representations of the pa rameter are given and methods are proposed to adjust this new measure for confounding and effect modification. Point estimates of the parame ter and their asymptotic variances are derived under different distrib utional assumptions. Advantages and limitations of this new approach f or assessing the public health impact of an exposure for recurrent dis ease event are discussed. (C) 1997 by John Wiley & Sons, Ltd.