Chan TLH, et al. - Researchers sought to determine naturally occurring clinical subgroups of posttraumatic headache (PTH), a headache developing within 7 days of an injury that lasts for greater than 3 months. The Stanford Research Repository Cohort Discovery Tool was used to conduct this retrospective study. Reviewing 500 electronic patient charts from January 2015 to September 2019, they included 300 patients [150 acute, 150 persistent PTH; median age: 47 years (IQR 31, 59); female: male ratio: of 2.7:1]. Preexisting psychological history, history of migraine, new PTH-associated comorbidities and medication overuse were noted to be predictive of the occurrence of persistent PTH as well as two naturally occurring PTH clusters correlating to acute and persistent PTH. They recommend focusing on these phenotypes in the management of these patients.