Ischemic stroke is a leading cause of morbidity and mortality worldwide. Dyslipidemia and inflammation play critical roles in its pathophysiology. The triglyceride/high-density lipoprotein cholesterol (TG/HDL-C) ratio has been suggested as a marker of atherogenic dyslipidemia, while C-reactive protein (CRP) serves as an inflammatory biomarker. This study aims to compare TG/HDL-C and CRP levels between ischemic stroke patients and a healthy control group.^[1] 

Because of its critical importance in atherogenesis, low-density lipoprotein (LDL) cholesterol is the focus of current guidelines for the determination of the risk of cardiovascular disease.^[1] However, atherothrombosis often occurs in the absence of hyperlipidemia, and recent consensus panels assembled by the National Heart, Lung, and Blood Institute and the Centers for Disease Control and Prevention have concluded that population-based data on other risk factors are urgently needed.^[2]

Among the biologic markers considered by those panels, there was particular interest in C-reactive protein, a marker of inflammation that has been shown in several prospective, nested case–control studies to be associated with an increased risk of myocardial infarction, stroke, sudden death from cardiac causes, and peripheral arterial disease.^[3] Although the results of these studies are highly consistent, limitations inherent in the design of nested case–control studies make it difficult to assess the relative merit of C-reactive protein. In particular, population-based cut off points for C-reactive protein remain uncertain, and reliable data describing receiver-operating-characteristic curves for C-reactive protein have not been available. Moreover, there are insufficient data from prospective cohort studies directly comparing the predictive value of C-reactive protein with that of LDL cholesterol. ^[4] 

In a previous hypothesis-generating report limited to 122 women in whom cardiovascular disease developed (case patients) and 244 controls who were participants in the Women's Health Study, we observed that several markers of inflammation, including C-reactive protein, had prognostic value for the detection of first vascular events over a three-year period. However, the relatively small number of events and the short follow-up limit the reliability of those data.^[4] Furthermore, because of the matched-pairs case–control study design, we were unable to define general population-based cut off points or to evaluate directly characteristics of C-reactive protein used as a diagnostic test.^[5-7]

We were able to calculate survival curves associated with C-reactive protein levels, to compare the predictive value of C-reactive protein and LDL cholesterol directly in a large, representative population sample, and to define the population distribution of C-reactive protein levels.^[6] We also determined the predictive value of each biologic marker among users and nonusers of hormone-replacement therapy; this is a clinically relevant issue, since hormone-replacement therapy affects levels of both C-reactive protein and LDL cholesterol. Finally, we evaluated whether C-reactive protein provided prognostic information on risk after adjustment for all components of the Framingham risk score.

A case-control study was conducted in the Department of Medicine at Tertiary Care Teaching Hospital. Patients including ischemic stroke patients and age- and sex-matched healthy controls. Serum TG, HDL-C, and CRP levels were measured and the TG/HDL-C ratio was calculated.

Inclusion Criteria: Adults aged 18 years or older Confirmed diagnosis of ischemic stroke based on clinical evaluation and neuroimaging (e.g., CT or MRI). Stroke onset within a specified time frame (e.g., within 72 hours of symptom onset).

Exclusion Criteria: Exclusion of individuals with hemorrhagic stroke, transient ischemic attack (TIA), or other non-ischemic cerebrovascular events. Presence of severe comorbidities that could confound results, such as: Advanced cancer, End-stage renal disease (on dialysis), Severe liver disease, Active autoimmune diseases (e.g., lupus, rheumatoid arthritis). Use of medications that significantly alter lipid profiles (e.g., statins, fibrates) or inflammation (e.g., corticosteroids, immunosuppressants) within a specified time frame prior to enrollment (e.g., 4 weeks).

Data collection

At baseline, information about demographic and socioeconomic status, lifestyle behaviors including dietary intakes, smoking status, physical activity, and medical history (e.g. the history of dyslipidemia, diabetes mellitus, hypertension, and medicine use) was collected using standard questionnaires through a 30-min home interview by trained staff. Anthropometric, blood pressure and laboratory measurements and physical examination were collected through participants’ attendance in the nearest health care clinic.

Blood pressure was measured using calibrated mercury sphygmomanometers twice after five minutes resting, and the mean was calculated as individual’s blood pressure. Height was measured using nonelastic tape without shoes to the nearest 0.5 cm, and weight was measured without shoes and with light clothing with a precision of 0.1 kg using a Seca scale. Individuals with systolic blood pressure (SBP) ≥ 140 mmHg and/or diastolic blood pressure (DBP) ≥ 90 mmHg and/or undergoing anti-hypertensive therapy were identified as hypertensive. Body mass index (BMI) assessment was performed by weight division (kg) by square height (m²). Subjects with BMI ≥ 30 kg/m² were categorized as obese

Biochemical measurements

Blood samples were gathered after 12 h fasting status and stored in laboratory of Institute at − 70 °C. Fasting blood glucose (FBG), serum total cholesterol (TC) and triglycerides (TG) were measured by the enzymatic method by a Hitachi auto-analyzer using special kits. High-density lipoprotein cholesterol (HDL-C) was determined enzymatically after precipitating other lipoproteins with dextran sulfate magnesium chloride. The Friedewald formula was utilized to calculate LDL-C in individuals with TG < 400 mg/dL. However, direct measurement of LDL-C was performed with a turbidimetric method for those with TG ≥ 400 mg/dL . In addition, apolipoprotein (apo) A and apo B were measured by photometric method. Abnormal serum lipid profiles were defined based on the National Cholesterol Education Panel Adult Treatment Panel III (NCEP-ATP III) as diabetes mellitus was defined as FBG ≥ 126 mg/dL and/or taking hypoglycemic medications . The participants with any of the TC ≥ 200 mg/dL, TG ≥ 150 mg/dL, LDL-C ≥ 130 mg/dL and/or HDL-C < 40 mg/dL for men and < 50 mg/dL for women were diagnosed with dyslipidemia. Hs-CRP measurement was carried out by the Cobas e-411 auto analyzer immunoturbidimetric method (Roche Diagnostics International Ltd, Basel, Switzerland) . Hs-CRP ≥ 3 mg/L has been indicated as a risk factor for CVD .

Statistical analysis

For quantitative variables, the independent sample t-test were used and manifested by mean ± standard deviation (SD). Categorical variable was analyzed using the Chi-square test and Fisher exact test and reported as numbers (percentages). Statistical analyses were carried out using Stata software, version 14 and R software version 4. In this report, p-values less than 0.05 were found statistically significant.

The baseline characteristics of the study participants, including age, sex, and blood pressure, are summarized in Table 1. The study population consisted of individuals aged 40 to 70 years. The mean age of the control group was 48.5±6.2 years, while the Acute Ischemic Stroke (AIS) group had a mean age of 54.7±7.5 years. The sex distribution was nearly equal, with 72 males and 38 females in the control group and 68 males and 42 females in the AIS group^.[8]

Upon admission, systolic and diastolic blood pressure readings were recorded. The mean blood pressure in the control group was 118/78 mmHg, whereas in the AIS group, it was significantly higher at 155/85 mmHg (p < 0.001).

Confounding variables such as smoking, diabetes mellitus, hypertension, and a history of cardiovascular disease were considered. Laboratory parameters, including inflammatory markers and lipid ratios, were analyzed to assess differences between AIS and control groups. The mean CRP level was significantly higher in AIS patients (0.35 mg%) compared to controls (0.08 mg%, p < 0.001), indicating a strong inflammatory response in AIS cases. Similarly, the TG/HDL-C ratio was significantly elevated in AIS patients (3.01) compared to the control group (2.45, p = 0.012). The correlation analysis (Table 4) indicated no significant relationship between CRP and TG/HDL-C in either group (p > 0.05).

Table 1: Baseline Characteristics of Study Participants

Table 2: Laboratory Parameters

Table 3: Correlation between CRP and TG/HDL-C

Table 4: Inflammatory Markers and Lipid Ratios in Control and AIS Groups

Table 5: Correlation between CRP and TG/HDL-C in Control and AIS Groups

No significant correlation was observed between CRP and TG/HDL-C levels in either group (p > 0.05).

In this prospective cohort of initially healthy women, we directly compared standard lipid measures, Apo lipoproteins B100 and A-I, and hs-CRP as risk determinants for future ischemic stroke as compared with coronary heart disease. Overall, we found that lipid levels are significantly associated with a risk of future ischemic stroke in a direction similar to that of coronary heart disease.[10] However, for all lipid measures, the magnitude of effect appeared smaller for future ischemic stroke than for CHD. While hs-CRP was a significant predictor of both clinical events, the magnitude of effect, if anything, was somewhat greater for ischemic stroke than for CHD. We could demonstrate no linear relationship between future hemorrhagic stroke and lipid or hs-CRP levels. No substantive differences were observed after exclusion of those with prevalent or incident atrial fibrillation.[11]

We believe these data are clinically relevant for several reasons. First, a clear link between lipids and future stroke has not been established. In our population of initially healthy U.S. women, non-HDL-C and HDL-C were associated with future ischemic stroke risk in a way that was clearly dose-dependent, while total cholesterol was also associated with future ischemic stroke in a somewhat weaker dose-dependent manner.[12] There was a trend towards an increased risk of ischemic stroke with increasing tertiles of apolipoproteins B100, A-I and LDL-C, although the trend was not significant. All the lipid ratios except the ratio of apolipoprotein B100 to A-I showed a consistently increasing risk of stroke with increasing levels of the ratio.[13]

As anticipated, lipid levels were all clearly associated with the risks of incident coronary heart disease. In all cases but one (the ratio of apolipoprotein B100 to A-I), the direction and magnitude of the association between the measured lipid variables and the endpoints of ischemic stroke and coronary heart disease were not significantly different. While ischemic stroke represents a heterogeneous disorder (33), these data provide evidence that in our population, hyperlipidemia confers a risk of both ischemic heart disease and ischemic cerebrovascular disease.[14]

Previous literature has noted the lack of association between lipids and ischemic stroke. Some studies have been unable to differentiate between hemorrhagic and ischemic stroke, and have suggested that cholesterol’s positive association with ischemic stroke may be concealed by a negative relationship with hemorrhagic stroke [15]. While a relationship between lipids and ischemic and hemorrhagic stroke was suggested by evidence from the MR FIT trial [16], we could not demonstrate a linear relationship between the risk of hemorrhagic stroke and lipid levels. We are significantly limited, however, by the number of hemorrhagic strokes (n=31) in our population. Other early research reports may have been limited by sample size [17], combining fatal and incident ischemic stroke [18], or examining only fatal stroke[18]

More recently, researchers working on a number of well-characterized cohorts such as the Atherosclerosis Risk in Communities Study (ARIC) [19] and the Physician’s Health Study [20] have reported similarly negative results. In the ARIC cohort, Shahar and colleagues reported a total of 305 ischemic strokes, 144 of which were in women. While they do not report the risk associated with elevated levels of total cholesterol, non-HDL-C or the total cholesterol to HDL-C ratio, which were the lipid measures that demonstrated the strongest association with future ischemic stroke in our cohort, the HRs of ischemic stroke among women for the highest versus the lowest quartile of LDL-C (HR 1.33; 95% CI, 0.81–2.20), apolipoprotein B100 (HR 1.61; 95% CI 0.96–2.69) and HDL-C (HR 0.68; 95% CI, 0.36–1.27) are quite similar to the HRs for extreme tertiles of those lipid measures we report here. An alternative explanation is that the population of women included in the WHS has fewer established risk factors for ischemic stroke than that recruited for ARIC, such that elevated lipid levels play a more central role in the pathophysiology of ischemic stroke among these women.[21]

While Bowman and colleagues were unable to show a relationship between cholesterol levels and ischemic stroke in a nested-case-control study of 296 ischemic strokes from the Physician’s Health Study , other studies performed exclusively in men have demonstrated a positive association between lipids and ischemic stroke[22]. Investigators working in a cohort of subjects enrolled in a health maintenance organization found an OR of 1.6 (95% CI, 1.3–2.0) of ischemic stroke for the highest versus the lowest quintile of total cholesterol and a protective effect of the highest levels of HDL-C (OR=0.8, 95% CI, 0.6 to 1.0 for extreme quintiles) [23], results that are consistent with recently published findings from Korea [24]. Sacco and colleagues, using an ethnically diverse community-based cohort in New York City, also demonstrated a protective effect of high HDL-C levels on the risk of ischemic stroke [25].

Another possibility is that while most ischemic stroke is the result of atherosclerotic processes, cardioembolic stroke (e.g., thromboembolism from atrial fibrillation) may not be closely associated with hyperlipidemia. While hs-CRP is a well-established marker of the systemic inflammation intrinsic to atherosclerosis in this cohort ^[26] and others, elevated levels of hs-CRP have also been associated with the presence of chronic and paroxysmal atrial fibrillation  and may predict incident atrial fibrillation . By capturing subjects who are predisposed to both etiologies of ischemic stroke, hs-CRP may serve as a more potent marker of future ischemic stroke than lipids alone. However, our findings that excluding subjects with atrial fibrillation does not substantially alter the point estimates of the hazard ratios for any of the lipids, their ratios, or hs-CRP does not support this hypothesis^[27]

Our analysis supports the use of standard lipid measures such as total cholesterol, HDL-C, non-HDL-C, and the ratio total cholesterol to HDL-C and hs-CRP in the assessment of risk for ischemic stroke in addition to coronary heart disease. While the risk of coronary heart disease for a given level of lipid may be somewhat higher than the risk of ischemic stroke, the risks are quite similar in direction. Inflammation, as measured by hs-CRP, and hyperlipidemia appear to play a key role in the development of cerebrovascular atherosclerosis and ischemic stroke, consistent with their well-known role in the pathophysiology of coronary atherosclerosis and coronary heart disease. ^[28]

This study reinforces the multifactorial nature of ischemic stroke and underscores the importance of a comprehensive approach to stroke prevention, including the management of inflammation, dyslipidemia, and hypertension. Early identification of high-risk individuals using biomarkers like CRP and TG/HDL-C ratio, along with targeted interventions, may help reduce the burden of ischemic stroke.

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