Improvements can be made by selecting target groups while using indices other than odds ratios

(ORs), relative risks (RRs) or incidence rate ratios (IRRs) alone, and in particular by studying the cumulative effect of joint exposures to several risk indicators rather than the effect of a single risk indicator. The proposed method can be carried out in several steps. First, a set of significant risk indicators is identified such that each of them has a statistically significant impact on the likelihood Inhibitors,research,lifescience,medical that the disorder will develop. To do this any of the available measures of association for binary outcomes (OR, RR or IRR) can be used. Second, if an OR can be calculated, then it is also possible to say Inhibitors,research,lifescience,medical how many people are exposed to that risk indicator. Call this measure “PI103 exposure rate” (ER). For prevention the ER is important, because it tells us howmany people have to be targeted by the preventive intervention. Clearly, smaller groups (smaller Inhibitors,research,lifescience,medical ER) are associated with less effort and hence lower costs of delivering the intervention. Third, with the OR and ER in hand one can calculate the population attributable fraction (AF).The AF indicates by

how many percent points the current incidence rate of the mental disorder in the population could be reduced when the adverse effect of the risk indicator is completely blocked.54-56 This equals the maximum possible health gain of a completely successful preventive intervention. Fourth, if the OR can be calculated, then

Inhibitors,research,lifescience,medical it is also possible to obtain the risk difference Inhibitors,research,lifescience,medical (eg, under a linear probability model) and its inverse: the number needed to treat (NNT). In the context of these analyses the NNT can be interpreted as the number of people who should be the recipients of a preventive intervention to avoid the onset of the disorder in one person. Again we have to assume that the preventive intervention is completely successful in containing the adverse effect of the risk factor. This assumption is not realistic, but the NNT may still help to Ribonucleotide reductase create a hierarchy of risk indicators to be targeted in prevention. Now comes the most important part of the method. We want to maximize the health gain (large AF) and minimize the effort to generate this health gain by targeting the smallest possible group (small ER) in the most efficient way (small NNT). Best values overall can be found by looking at combinations of risk indicators. That is, we can see what combinations of exposures (joint exposures) help to minimize and maximize the indices, such that a target group is selected where prevention is most likely to become cost-effective.