Fig. 2

Clusters within persistent PTH patients. Four clusters of persistent PTH patients were identified (a). Under each cluster column, the following clinical variables were coded as “present” and “absent”: PPH_P (previous psychological history in persistent PTH), MO (medication overuse), MigHis (migraine history), PMH (previous medical history), LOC (loss of consciousness), NewCom (new comorbidities). “Present” is depicted by the left bars under each cluster column, while “absent” is represented by the right bars. For sex, left bars represent males while right bars represent females. The seven bars in previous head injury (PrevHI) represent frequency of head injuries found ranging from 0 (left) to 7 (right). Age distribution is shown ranging from 18 (left) to 90 (right) years. Cluster 1 had the lowest prevalence of a history of migraine (i.e. highest bar for “absent” MigHis). Cluster 2 featured the highest level of pre-existing psychological history, medication overuse, history of migraine, loss of consciousness, and the longest PTH duration (median 30 months). Cluster 3 had the shortest PTH duration (median 24 months) and the lowest prevalence of loss of consciousness. Cluster 4 exhibited the lowest prevalence of new PTH-associated comorbidities and head injuries (a). The top 3 important predictors in descending order were pre-existing psychological history, medication overuse, and history of migraine (b)