Prognostic significance of serum cystatin C in acute ischemic stroke patients according to lipid component levels

Background and aims: Serum cystatin C (CysC) is associated with the risk of ischemic stroke and may predict cardiovascular events and death after ischemic stroke onset. However, the association between serum CysC and functional outcome in ischemic stroke patients remains unclear, and whether lipid component level influences the relationship between them has not been studied. Methods: A total of 3348 ischemic patients from China Antihypertensive Trial in Acute Ischemic Stroke were included in the study. Serum CysC was used to calculate estimated glomerular filtration rate (eGFR_CysC) at baseline. The primary outcome was poor functional outcome (modified Rankin Scale score ≥3) at one year after ischemic stroke. Secondary outcomes were death, stroke recurrence, vascular events and combination of the aforementioned outcomes. Results: The association between eGFR_CysC and primary outcome was appreciably modified by low-density lipoprotein cholesterol (LDL-C) (p_interaction = 0.048). Low eGFR_CysC was associated with primary outcome only in ischemic stroke patients with LDL-C ≥4.14 mmol/l rather than all patients. The multivariable adjusted odds ratio (95% confidence interval) of poor functional outcome associated with low eGFR_CysC was 3.94 (1.04–14.98) and a positive linear dose-response relationship between them was observed among patients with LDL-C ≥4.14 mmol/l (p for linearity = 0.021). Subgroup analyses further confirmed these associations. There was no association between eGFR based on serum creatinine and poor functional outcome of stroke. Conclusions: Low eGFR_CysC may be an independent predictor for 1-year poor functional outcome in ischemic stroke patients with LDL-C ≥4.14 mmol/l. Further studies are needed to replicate our findings and to clarify the potential mechanisms.