Abstract
Cluster headache is a severe primary headache disorder, which can be associated with a substantial impairment for sufferers. The Cluster Headache Impact Questionnaire (CHIQ) is a short questionnaire for measuring the cluster headache-specific impairment. A 5-stage severity grading from "no to low impairment" to "'extreme impairment" was established based on the results of an English-speaking patient collective. The present article tested whether the severity classification can be transferred to a German patient group. Data from 196 patients with episodic and chronic cluster headache were examined during an active episode. The severity grading classification of the CHIQ also showed clinically relevant results in the German collective, i.e., the five degrees of severity showed significant differences with respect to attack frequency, intake of acute medication and unspecific headache-related impairment (HIT-6) and quality of life (SF-12v2). Interestingly, 32 out of 52 patients with episodic cluster headache outside the active epísode suffered an impairment above the lowest severity grade, i.e., at least a moderate impairment. In conclusion, the CHIQ provides a short instrument to document the current impairment in cluster headache patients. The severity grading classification presented here facilitates the clinical interpretation.