Methods for reducing sample size of clinical trials are disclosed herein. In an embodiment, a method for calculating a sample size for a clinical trial includes choosing values for power, level of significance and size of treatment effect sought for a particular event; selecting a subgroup of people for the clinical trial from a selection of subgroups, the subgroup having a higher value for an event rate than the remaining subgroups; and calculating the sample size for the clinical trial using the values for power, level of significance, size of treatment effect sought and the subgroup event rate, wherein the people of the subgroup have a lower gelsolin concentration than a predetermined baseline value of gelsolin.