A Systematic Review of the Diagnostic Criteria Used to Select Participants in Randomised Controlled Trials of Interventions Used to Treat Cervicogenic Headache.

OBJECTIVE

The aim of this study was to determine the diagnostic criteria used in randomized controlled trials to define trial participants as having cervicogenic headache (CeH).

BACKGROUND

While animal and human studies suggest a biological basis for "cervicogenic" headaches the diagnostic criteria necessary to evidence CeH are debated.

METHODS

A systematic review was undertaken guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. An electronic search of MEDLINE, Cochrane, CINHAL, Pedro, AMED, and EMBASE online databases of randomized controlled trials published between January 1983 and October 2018 found 39 randomized controlled trials which met the study inclusion criteria.

RESULTS

Two independent reviewers found most trials cited 1 (31/39; 79.5%) or more (3/39; 7.6%) references to define the criteria used to identify CeH in their study participants. In spite of updated publications concerning the characteristics and definition of CeH, many (27/39; 69.2%) used diagnostic criteria published between 5 and 24 years prior to the randomized controlled trial. The most commonly cited diagnostic criteria included unilateral headache (18/39; 46.2%), cervical movement or sustained posture that either provoked (18/39; 46.2%) or precipitated (17/39; 43.6%) the headache. Fifteen trials did not exclude participants with signs or symptoms of other forms of headache. Although anesthetic blockade of cervical tissue or nerves is considered necessary for a "definitive" diagnosis, only 7.6% (3/39) of trials used anesthetic blockade at recruitment.

CONCLUSIONS

This systematic review evidences the heterogeneity in the clinical characteristics used to diagnose CeH in participants recruited in randomized controlled trials. It raises a significant concern about the usefulness of currently available randomized controlled trials to determine the clinical merits of the treatment and management of people with CeHs. Our systematic review suggests that most randomized controlled trials published to date have investigated headaches with a clinical presentation involving the neck that maybe better defined as "possible," "probable," or "definitive" CeH depending on how well the diagnostic criteria used align with the most recent edition (3rd) of the International Classification of Headache Disorders.