Prevalence and Features of a Probable Diagnosis in First-Visit Headache Patients Based on the Criteria of the Third Beta Edition of the International Classification of Headache Disorders: A Prospective, Cross-Sectional Multicenter Study.

Objectives: This study aimed to determine the characteristics and significance of a probable diagnostic entity for primary headache disorder (PHD).

Background: A diagnosis of probable primary headache disorder (PPHD) is given when a patient's headache fulfills all but one criteria of the third beta edition of the international classification of headache disorder (ICHD-3β). Despite the uncertainty regarding this diagnosis, the inclusion of a probable diagnosis entity in this manual may aid in the accurate classification of headache disorders and allow effective treatment strategies to be started at the patient's initial visit.

Methods: This cross-sectional multicenter registry study assessed first-visit patients with complaints of headaches who presented at the outpatient clinics of 11 neurologists in Korea. The classification of a headache disorder was made according to the criteria of the ICHD-3β by each investigator based on the initial evaluation of the patient or by a consensus meeting for uncertain cases. The rates of a probable diagnosis among PPHD patients were assessed and the clinical characteristics of these patients were compared with those of patients with a diagnosis of definite primary headache disorder (DPHD).

Results: A total of 1429 patients were diagnosed with PHD, and 305 (21.3%) of these patients had PPHD. The proportions of PPHD differed among the subtypes of DPHD as follows: migraines (16.1%), tension-type headaches (TTH; 33%), trigeminal autonomic cephalalgia (TAC; 40.9%), and other PHD (14%, P < .001). Patients with PPHD had less severe headache intensity than patients with DPHD (5.8 ± 2.2 vs. 6.5 ± 2.1, respectively, P < .001) as well as a shorter duration of headache from onset (median: 1 vs. 4 months, respectively, P < .001). The most common criteria missing for a definite diagnosis in the PPHD patients were total frequency (52.1%), duration of attack (14.4%), and accompanying symptoms (13.1%).

Conclusions: A probable diagnosis was given to 21.3% of the first-visit PHD patients due to incomplete or atypical presentations of the headaches. The incorporation of a probable diagnosis into the ICHD-3β may be useful for reducing the diagnoses of unspecified headaches.