We also evaluated the capacity of RPS to predict case-control status using a standard epidemiological approach to a continuous risk factor. We illustrate this in three samples, each with different ascertainment schemes (Figure 3). The Danish sample is population-based (i.e. inpatient and outpatient facilities), the Sweden sample is based on all cases hospitalized for schizophrenia in Sweden, and the MGS study was ascertained specially for genetic studies from clinical sources in the US and Australia. We grouped individuals into RPS deciles and estimated the odds ratios for affected status for each decile with reference to the lowest risk decile. The odds ratios increased with greater number of schizophrenia risk alleles in each sample, maximizing for the tenth decile in all samples: Denmark 7.8 (95% CI 4.4-13.9), Sweden 15.0 (95% CI 12.1-18.7), and MGS 20.3 (95% CI 14.7-28.2). Given the need for measures that index liability to schizophrenia,47,48 the ability to stratify individuals by RPS offers new opportunities for clinical and epidemiological research. Nevertheless, we stress that the sensitivity and specificity of RPS do not support its use as a predictive
