A bivariate Pearson correlation showed a medium correlation between higher CGRP and a shorter lag from the last headache attack (r = −0.41; p < 0.05), but none for the last migraine attack (r = −0.16; p = 0.963) or the number of peri-interventional headache days (r = 0.282; p = 0.139). This evidence concerns the gene CALCA and Headache.