Blood Count-Derived Inflammatory Indices at Two Timepoints in Insulin-Treated Gestational Diabetes: A Retrospective Cohort Study.

PURPOSE: Complete blood count-derived inflammatory indices are widely studied in pregnancy, with inconsistent findings; if they capture a persistent maternal characteristic, a woman's value at one timepoint should locate her value at another. We examined within-woman tracking of six indices, and their relation to fetal overgrowth, in insulin-treated gestational diabetes (GDM). PATIENTS AND METHODS: Retrospective cohort of 358 women with insulin-treated GDM at a tertiary centre. Six indices (NLR, PLR, MLR, SII, SIRI, PIV) were calculated at the oral glucose tolerance test (OGTT, 24-28 weeks) and at delivery admission, two physiologically distinct occasions. The primary outcome was large-for-gestational-age (LGA) birth (INTERGROWTH-21st); macrosomia was secondary. Tracking was quantified by Spearman correlation and the between-woman variance share from a mixed model. Analytic samples were 358 (group comparisons, discrimination), 353 (paired) and 284 (adjusted models), one lower in each for MLR, SIRI and PIV. RESULTS: LGA occurred in 139 infants (38.8%). No index discriminated LGA to a clinically useful degree (AUC 0.51-0.57). Adjusted for body-mass index (BMI) and HbA1c, SIRI was associated with LGA (OR 1.64 per standard deviation, 95% CI 1.18-2.39; n = 283) and survived Bonferroni correction (corrected P = 0.040), though not consistently across samples; we regard this nominal finding as exploratory. BMI and HbA1c, per standard deviation, had odds ratios of 1.42 and 1.48 and numerically higher AUCs (0.63 each). All six indices changed between the two occasions (all P<0.001); within-woman rank correlation was weak to moderate (ρ 0.27-0.54) and the between-woman variance share 0.25-0.56. CONCLUSION: CBC-derived indices tracked poorly within women between the two occasions, and none discriminated LGA to a clinically useful degree. Whether this reflects instability of the underlying inflammatory state or the differing clinical circumstances of the two samples cannot be determined from this design.