Tracking complete blood count-derived indices during transition to euthymia in bipolar disorder: a longitudinal study

This study aims to investigate changes in the CBC-related inflammatory indices in hospitalized bipolar disorder (BD) patients transitioning from a mood episode to a euthymic state.

BD patients hospitalized for mania or depression were assessed during hospitalization and one month post-discharge in euthymia. In both phases, CBC was assessed, along with the administration of YMRS, HDRS-17, and the CGI.

Ninety-four patients (58 manic, 36 depressive episodes) met the inclusion criteria at both phases. Significant decreases were observed in WBC (p < 0.001), neutrophils (p = 0.002), platelets (p = 0.038), NLR (neutrophil-to-lymphocyte ratio, p = 0.019), AISI (aggregate index of systemic inflammation, p < 0.001), dNLR (derived neutrophil-to-lymphocyte ratio, p = 0.007), SII (systemic immune inflammation index, p = 0.002), and SIRI (systemic inflammation response index, p = 0.003), while eosinophils (p = 0.003), EMR (eosinophil-to-monocyte ratio, p = 0.002), and ENR (eosinophil-to-neutrophil ratio, p = 0.001) increased. After a Bonferroni correction (p < 0.003125), changes in WBC, neutrophils, AISI, SII, SIRI, EMR, and ENR remained significant. Furthermore, differences were also noted between VPA users and non-users.

The study highlights distinctive changes in CBC-related indicators during the transition to euthymia in BD patients. It is the first to investigate specific indices such as AISI, dNLR, EMR, and ENR in BD using a longitudinal design. The findings suggest that CBC-derived inflammation indices are promising tools for monitoring BD clinical progression.