Other strong predictors were age > 50 years (OR 2.77, 95%CI 1.72–4.46), an abnormal neurologic exam (OR 4.23, 95%CI 2.47–7.24), thunderclap onset of headache (OR 3.04, 95%CI 1.75–5.29), clinical scenario 4 (history of previous similar headache; OR 0.56, 95%CI 0.32–0.97), and C-reactive protein (OR 1.31, 95%CI 1.07–1.60; see also Table 4a). This evidence concerns the gene CRP and Headache.