Evaluation of haematological inflammatory ratios in migraine: a systematic review and meta-analysis

Haematological inflammatory ratios, including the neutrophil-to-lymphocyte ratio (NLR), have emerged as potential biomarkers in various neurological disorders. This systematic review and meta-analysis aimed to evaluate these ratios in patients with migraine compared with healthy controls and other headache disorders, and to assess differences across migraine subtypes and clinical phases. The systematic review with meta-analysis was conducted according to the PRISMA guidelines.

PubMed (MEDLINE), Web of Science, Scopus, the Cochrane Library, MEDLINE Ultimate, and Embase were searched from their inception to 26 April 2025. Additionally, backward and forward citation searches were performed. Risk of bias was assessed using the Newcastle–Ottawa Scale.

Random-effects models employing the DerSimonian–Laird method and Hartung–Knapp adjustment were used to estimate pooled mean values with 95% confidence intervals. Heterogeneity was quantified with the I² and Cochran’s Q tests. Publication bias was assessed using funnel plots and Begg’s test.

Twenty-three studies met the inclusion criteria, and 21 were included in the meta-analysis. The pooled mean NLR was significantly higher in patients with migraine compared to healthy controls, particularly in those with migraine with aura and during the ictal phase. No significant differences were found between migraine and tension-type headache.

Other ratios showed no significant intergroup differences. Substantial heterogeneity and the observational design of included studies were noted as limitations. Among the evaluated ratios, the NLR appeared to most consistently reflect inflammatory processes in migraine, especially in migraine with aura and during the ictal period.

However, its clinical utility remains uncertain and further studies are needed to clarify their potential role as diagnostic and prognostic biomarkers. PROSPERO registration: CRD420251041190. No external funding was received.