Pilot cluster randomized controlled trial of a complex intervention to improve management of vertigo in primary care (PRIMA-Vertigo): study protocol.

OBJECTIVES: Vertigo and dizziness are highly prevalent symptoms in primary care, frequently misdiagnosed. Based on a thorough need assessment, INDICORE (INform, DIagnose, COmmunicate, REfer), an evidence-based complex intervention has been developed to transfer knowledge of specialized tertiary clinics to primary care providers (PCPs), improve the referral process and, ultimately, improve the functioning and quality of life of patients with vertigo/dizziness. The main objective of the PRIMA-Vertigo pilot study is to examine whether the INDICORE intervention is feasible and sufficiently promising to warrant a larger trial.

METHODS: We plan to perform a single-blind, pragmatic cluster-randomized controlled pilot study with an accompanying process evaluation. PCPs will be the cluster units of randomization. Patients who consult these PCPs because of vertigo/dizziness symptoms will be included consecutively and considered the units of analysis. The intervention will be multi-faceted training on diagnostics targeted at the PCPs, supported by patient education material and a newly developed tool to structure the referral process. To balance the influence of non-specific effects, all clusters will receive generic communication training.

EXPECTED RESULTS: The process evaluation aims to provide results on the acceptability and feasibility of the INDICORE intervention components to PCPs and patients. Additionally, this study will provide a first estimate of the likely effectiveness of the intervention on patients' quality of life, functioning and participation.

CONCLUSIONS: The PRIMA-Vertigo pilot study will allow further tailoring of the INDICORE intervention to stakeholder needs before its effectiveness is evaluated in a large-scale main study.