The clinical data of 242 AIS patients admitted to our hospital from April 2020 to October 2021 were collected and analysed. The inclusion criteria for patients were as follows: (1) met the diagnostic criteria of the World Health Organization (WHO) for AIS confirmed by craniocerebral magnetic resonance imaging (MRI) or computed tomography (CT) scans ; (2) had an AIS onset time within 6–48 hours; (3) age ≥ 18 years; and (4) had complete clinical data available. The exclusion criteria were as follows: (1) emergency intravenous thrombolysis or endovascular intervention; (2) previous history of intracerebral haemorrhage, subarachnoid haemorrhage, brain trauma, or brain tumour; (3) severe infection, autoimmune disease, malignant tumour or blood system disease; and (4) severe dysfunction of the heart, liver, or kidney.
All of the participants signed an informed form to participate in the study. The study design was approved by the Medical Ethics Committee of Huai’an Hospital affiliated to Xuzhou Medical University.
Collection of baseline data
Data on demographic and clinical characteristics were collected at admission, including age, sex, smoking status, alcohol consumption, history of related diseases (diabetes, hypertension, stroke, atrial fibrillation and coronary heart disease), premorbid medications (antithrombotics, anticoagulants and statins), baseline systolic and diastolic blood pressure, National Institutes of Health Stroke Scale (NIHSS) score, and Alberta Stroke Program Early CT (ASPECT) score. Laboratory data, including hs-CRP, lipid profle results, fasting plasma glucose (FPG), homocysteine (HCY), blood coagulation indicators and creatinine (Cr), were also recorded. All tests were performed with a fully automated biochemical analyser (Beckman 5811, Germany).
Lp-PLA2 concentration assessment
Fasting venous blood was collected from all patients within 24 h of admission and placed in EDTA-treated tubes. Blood samples were centrifuged at 1500 r/min for 10 minutes, and the separated plasma was stored at 4 °C. Next, the plasma levels of Lp-PLA2 were measured by magnetic microparticle chemiluminescence in an MQ60 series automatic immune analyser according to the kit’s instructions. Reagents were provided by Beijing Rejing Biotechnology Co., Ltd.
Cranial MRI was performed using a 3.0 T MRI scanner (General Electric Medical Systems, USA). All patients completed the following sequences within 72 hours of admission: T1-weighted imaging (repetition time [TR], 1750 ms; echotime [TE], 24 ms; fifield of view [FOV], 24 × 18 cm; matrix, 320 × 224; slice thickness, 5 mm), T2- weighted imaging (TR, 4841 ms; TE, 102 ms; FOV, 24 × 24 cm; matrix, 256 × 256; slice thickness, 5 mm), fluid-attenuated inversion recovery (FLAIR) (TR, 9000 ms; TE, 130 ms; FOV, 24 × 24 cm; matrix, 256 × 192; slice thickness, 5 mm), diffusion weighted imaging (DWI) (TR, 4880 ms; TE, 65 ms; b-value, 0/1000;FOV, 24 × 24 cm; matrix, 160 × 130; slice thickness, 5 mm), SWI (TR, 85 ms; TE, 45 ms;flip angle,15°;FOV, 24 × 22 cm; matrix, 384 × 320; slice thickness, 2 mm;slice gap, 0 mm). All imaging results were observed and assessed by two experienced neuroradiologists. If disagreements arose, the two doctors discussed the case until they reached an agreement.
The positive diagnostic criteria for CMBs in SWI results were as follows : round or oval hypointense signals with a diameter of 2 ~ 5 mm (maximum of no more than 10 mm), with clear borders, without oedema around the focus, and excluding calcium or iron deposition, vascular flow void effect, diffuse axonal injury, cavernous haemangioma or other conditions with similar imaging manifestations.
White matter lesions (WMLs) were defined as high signal intensity in T2-weighted images and FLAIR sequences of cranial MRI results, equal or slight signal on T1-weighted images, and focuses that were punctate or patchy with blurred borders and diameters ≥5 mm .
WMLs were assessed according to the Fazekas score , which included two categories: periventricular hyperintensity (PVH) and deep white matter hyperintensity (DWMH) scores. (1) PVH scores were as follows: 0 for no lesions, 1 for cap or pencil-like thin-layer lesions, 2 for smooth halo lesions, and 3 for lesions extending to deep white matter; (2) DWMH scores were as follows: 0 for no lesions, 1 for spotted lesions, 2 for plaque-like partial fusion lesions and 3 for diffuse large fusion lesions. The final Fazekas score was calculated as the sum of the PVH and DWMH scores.
All statistical analyses were performed using SPSS version 25.0 (SPSS Inc., Chicago, IL, USA). Normally distributed data are expressed as the mean ± standard deviation (SD), and group comparisons were performed by two independent-sample t tests. Nonnormally distributed data are expressed as the median and interquartile range. Group comparisons were made with the Mann–Whitney U test. Count data are expressed as the number and percentage (n, %), and group comparisons were performed using the chi-square test. Univariate and multivariate logistic regression analyses were used to evaluate the correlation between Lp-PLA2 levels and CMBs. A receiver-operating characteristic curve (ROC) was used to estimate the optimal cut-off value of Lp-PLA2 for predicting CMBs in patients with AIS, and the area under the curve (AUC), sensitivity and specificity of the ROC were evaluated. Statistical significance was established at P < 0.05 in all tests.