Plasma cyclic glycine proline/IGF‐1 ratio predicts clinical outcome and recovery in stroke patients

OBJECTIVE: Many stroke patients make a partial recovery in function during the first 3 months, partially through promoting insulin‐like growth factor‐1 (IGF‐1) function. A prognostic biomarker that associates with IGF‐1 function may predict clinical outcome and recovery of stroke. This study evaluated plasma concentrations of IGF‐1, IGF binding protein (IGFBP)‐3 and cyclic‐glycine‐proline (cGP) and their associations with clinical outcome in stroke patients. METHODS: Thirty‐four patients were recruited within 3 days of stroke. Clinical assessments included the National Institutes of Health Stroke Scale (NIHSS) within 3 days (baseline), and at days 7 and 90; the modified Rankin Scale (mRS) and Fugl‐Meyer Upper‐Limb Assessment Scale (FM‐UL) at days 7 and 90. Plasma samples were collected from the patients at the baseline, days 7 and 90. Fifty age‐matched control participants with no history of stroke were also recruited and provided plasma samples. IGF‐1, IGFBP‐3, and cGP concentrations were analyzed using ELISA or HPLC‐MS. RESULTS: Baseline concentrations of IGFBP‐3, cGP, and cGP/IGF‐1 ratio were lower in stroke patients than the control group. The neurological scores of stroke patients were improved and plasma cGP and cGP/IGF‐1 ratio increased over time. Baseline cGP/IGF‐1 ratio was correlated with the NIHSS scores at day 90 and the changes in NIHSS scores from the baseline to 90 days. INTERPRETATION: Low cGP concentrations and cGP/IGF‐1 ratio in stroke patients suggest an impaired IGF‐1 function. The cGP/IGF‐1 ratio at admission maybe further developed as a prognostic biomarker for stroke recovery.