Chronic kidney disease (CKD) confers a markedly elevated risk of cardiovascular disease (CVD), particularly coronary artery disease (CAD), beyond traditional risk factors. Among the non-traditional factors, hyperhomocysteinemia is common in CKD as glomerular filtration rate declines, largely due to impaired renal clearance and altered metabolism of homocysteine (Hcy) [1,2]. Mechanistically, elevated Hcy has been linked to endothelial dysfunction, oxidative stress, smooth-muscle proliferation, and pro-thrombotic effects, offering biologically plausible pathways to atherosclerosis and myocardial ischemia [3]. Observational studies across general and renal populations have reported higher Hcy levels in those with atherosclerotic disease, including in end-stage renal disease (ESRD) cohorts where Hcy elevations are pronounced [4, 5]. A body of literature associates higher Hcy with CAD presence and severity, although certainty varies and heterogeneity is substantial [6, 7]. Together, these data suggest Hcy may act as a risk marker and potentially a mediator of CAD in CKD. Despite consistent biochemical and observational signals, trials of homocysteine-lowering therapy with folate and B-vitamins have yielded mixed cardiovascular results in CKD. Large randomized studies and meta-analyses in advanced CKD/ESRD and transplant recipients generally failed to show reductions in hard cardiovascular endpoints with folate-based Hcy lowering, tempering causal claims [8]. A post-hoc pattern suggests possible benefit in regions without folate grain fortification or in subgroups with advanced CKD, but overall effects remain modest and inconsistent [9]. This divergence strong association yet limited interventional benefit keeps open the question of whether Hcy is a modifiable mediator or primarily a risk marker that tracks with uremic milieu and other CKD-related vascular insults. Important gaps persist for clinical decision-making in CKD: (i) contemporary, stage-stratified estimates of the association between serum Hcy and angiographically confirmed CAD in non-dialysis CKD; (ii) clarity on dose–response or threshold relations across CKD stages; (iii) adjustment for confounders common in CKD (e.g., folate/B-vitamin status, inflammation, mineral bone disorder, anemia) that can co-vary with Hcy; and (iv) data from under-represented populations where background folate exposure and diet differ, which may modify the Hcy–CAD link [2,3]. Recent systematic reviews emphasize that while higher Hcy often tracks with CAD, the overall certainty of evidence is low to moderate because of heterogeneity, residual confounding, and outcome ascertainment issues underscoring the need for rigorously phenotyped CKD cohorts with standardized CAD assessment [5]. Aim of the study was to evaluate the association between serum homocysteine levels and coronary artery disease among patients with chronic kidney disease, assessing both the presence and angiographic severity of CAD after adjustment for key clinical and biochemical confounders. This study will help clarify whether serum Hcy independently correlates with CAD burden across CKD stages in a contemporary cohort.

Study Design and Setting: This was a cross-sectional, observational study conducted in the Department of Medicine, Mamata Medical College, Khammam. Seventy-five (n=75) adult patients with chronic kidney disease (CKD) attending inpatient and outpatient services were enrolled consecutively over the study period after screening for eligibility. Participants (Inclusion/Exclusion): Inclusion criteria were age ≥18 years and CKD stages 1–5 (not on dialysis), defined and staged by KDIGO using the 2021 CKD-EPI creatinine equation for eGFR. Exclusion criteria included acute kidney injury, current dialysis, known B12 or folate deficiency under treatment or supplementation within the past 3 months, acute coronary syndrome or revascularization within the past 4 weeks, active infection or inflammatory disease, hypothyroidism or hyperthyroidism, pregnancy, malignancy, chronic liver disease, and use of drugs known to affect homocysteine (e.g., methotrexate, antiepileptics). Written informed consent was obtained from all participants, and the protocol was approved by the Institutional Ethics Committee. Clinical Data and Definitions: Demographic data, cardiovascular risk factors (hypertension, diabetes, dyslipidemia, smoking), medications, and CKD etiology were recorded using a structured proforma. Blood pressure was measured using standard methods. Diabetes and hypertension were defined by established diagnostic criteria or current treatment. Body mass index was calculated from measured height and weight. Laboratory Measurements: After an overnight fast (8–12 h), venous blood was collected. For homocysteine (Hcy), EDTA plasma was placed on ice, centrifuged within 30 minutes, and stored at −80 °C until analysis to minimize ex vivo Hcy generation. Serum homocysteine was measured by enzymatic immunoassay (or HPLC where available) following manufacturer guidance and internal quality control. Serum creatinine, fasting lipid profile, fasting glucose, and high-sensitivity C-reactive protein (hs-CRP) were measured by standard automated methods in the hospital laboratory. Serum vitamin B12 and folate were assayed by chemiluminescent immunoassay to allow adjustment for vitamin status. eGFR was calculated using the CKD-EPI 2021 equation, and CKD was staged per KDIGO. Coronary Artery Disease Assessment: Coronary artery disease (CAD) was defined as ≥50% diameter stenosis in at least one major epicardial coronary artery on invasive coronary angiography or a documented history of prior MI/PCI/CABG. In patients who underwent angiography during the admission/clinic evaluation, CAD severity was quantified using the Gensini score (scored by two blinded physicians; disagreements resolved by consensus). For secondary analyses, we also classified multivessel disease (≥2 vessels with ≥50% stenosis). Outcomes: The primary outcome was the association between serum homocysteine levels and presence of CAD. Secondary outcomes included the relationship between homocysteine and angiographic severity (Gensini score) and stage-wise differences across CKD stages. Sample Size and Sampling: A total of 75 consecutive eligible patients were included as a pragmatic sample to generate pilot data in this population and setting. This sample allows estimation of effect sizes and feasibility parameters for future powered studies. Statistical Analysis: Data were analyzed using SPSS (v26) or R (v4.3). Continuous variables were summarized as mean ± SD or median (IQR) based on Shapiro–Wilk normality testing; categorical variables as counts and percentages. Group comparisons (CAD vs no CAD) used t-test or Mann–Whitney U for continuous data and χ²/Fisher’s exact test for categorical data. Correlations between homocysteine and Gensini score used Spearman’s rho. Multivariable logistic regression assessed the independent association of homocysteine (per 5 µmol/L increase and by tertiles) with CAD after adjusting for age, sex, diabetes, hypertension, LDL-C, smoking, eGFR, hs-CRP, vitamin B12, and folate. For angiographic severity, multivariable linear regression (Gensini score log-transformed if skewed) was performed with the same covariates. Model assumptions and goodness-of-fit were checked; multicollinearity was assessed by VIF. Two-sided p<0.05 was considered statistically significant. Ethical Considerations: The study adhered to the Declaration of Helsinki. Institutional Ethics Committee approval was obtained prior to initiation, and all participants provided written informed consent. Confidentiality was maintained throughout.

Table 1. Baseline characteristics and key laboratory values (overall and by CAD status) Variable Overall (n=75) CAD Present (n=38) CAD Absent (n=37) Age, years 58.4 ± 10.6 60.7 ± 9.4 56.0 ± 11.3 BMI, kg/m² 26.1 ± 3.4 26.6 ± 3.2 25.6 ± 3.5 eGFR (CKD-EPI 2021), mL/min/1.73 m² 39.5 ± 16.2 36.1 ± 15.1 43.1 ± 16.8 LDL-C, mg/dL 102 ± 34 110 ± 36 94 ± 30 HDL-C, mg/dL 41 ± 9 39 ± 8 43 ± 9 Triglycerides, mg/dL 176 ± 68 188 ± 72 163 ± 61 hs-CRP, mg/L 3.9 ± 2.6 4.6 ± 2.7 3.1 ± 2.2 Vitamin B12, pg/mL 324 ± 118 311 ± 112 337 ± 123 Folate, ng/mL 8.7 ± 3.4 8.2 ± 3.1 9.2 ± 3.6 Serum Homocysteine, μmol/L 22.6 ± 8.2 26.8 ± 8.1 18.2 ± 6.1 Gensini score (CAD+ only) 28.5 ± 16.9 In this cross-sectional sample of adults with CKD (N = 75), participants with angiographically confirmed CAD (n = 38) were older (M = 60.7, SD = 9.4 years) than those without CAD (M = 56.0, SD = 11.3) and had lower kidney function, with eGFR averaging 36.1 (SD = 15.1) versus 43.1 (SD = 16.8) mL/min/1.73 m². The CAD group showed a more adverse lipid and inflammatory profile—higher LDL-C (M = 110, SD = 36 mg/dL vs. M = 94, SD = 30), lower HDL-C (M = 39, SD = 8 mg/dL vs. M = 43, SD = 9), higher triglycerides (M = 188, SD = 72 mg/dL vs. M = 163, SD = 61), and higher hs-CRP (M = 4.6, SD = 2.7 mg/L vs. M = 3.1, SD = 2.2). Vitamin status was modestly lower in CAD (vitamin B12: M = 311, SD = 112 pg/mL; folate: M = 8.2, SD = 3.1 ng/mL) compared with non-CAD (B12: M = 337, SD = 123; folate: M = 9.2, SD = 3.6). Notably, serum homocysteine was higher in CAD (M = 26.8, SD = 8.1 µmol/L) than in non-CAD (M = 18.2, SD = 6.1), consistent with a more atherogenic and inflammatory milieu. Among CAD-positive participants, angiographic severity was moderate on average (Gensini score: M = 28.5, SD = 16.9). Overall means for the cohort were: age M = 58.4 (SD = 10.6) years, BMI M = 26.1 (SD = 3.4) kg/m², eGFR M = 39.5 (SD = 16.2) mL/min/1.73 m², LDL-C M = 102 (SD = 34) mg/dL, HDL-C M = 41 (SD = 9) mg/dL, triglycerides M = 176 (SD = 68) mg/dL, hs-CRP M = 3.9 (SD = 2.6) mg/L, vitamin B12 M = 324 (SD = 118) pg/mL, folate M = 8.7 (SD = 3.4) ng/mL, and homocysteine M = 22.6 (SD = 8.2) µmol/L (Table Table 2. Coronary Artery Disease Assessment in CKD Patients (n=75) CAD Parameter CAD Present (n=38) CAD Absent (n=37) Total (n=75) Presence of CAD (≥50% stenosis) 38 (50.7%) 37 (49.3%) 75 (100%) Single-vessel disease 14 (36.8%) Double-vessel disease 12 (31.6%) Triple-vessel disease 10 (26.3%) Left Main Coronary Artery Involvement 2 (5.3%) Mean Gensini Score 28.5 ± 16.9 Gensini score range 8–72 In this CKD cohort (N = 75), angiographically defined CAD (≥50% stenosis) was present in 50.7% (38/75).Among those with CAD (n = 38), involvement was commonly beyond a single territory: single-vessel diseaoccurred in 36.8% (14/38), double-vessel in 31.6% (12/38), and triple-vessel in 26.3% (10/38), with left maininvolvement in 5.3% (2/38). Angiographic severity, quantified by the Gensini score, showed a moderate average burden (M = 28.5, SD = 16.9; range = 8–72). Taken together, approximately three in five CAD-positive patients had multivessel disease, indicating that when CAD is present in CKD it is frequently extensive and oat least moderate severity information that supports comprehensive cardiovascular risk stratification and management in this population (Table 2). Table 4. Correlation Between Serum Homocysteine and CAD Severity (Gensini Score, CAD+ only, n=38) Variable r-value p-value Homocysteine vs. Gensini score 0.46 0.004 In the CAD-positive subgroup (n = 38), serum homocysteine showed a moderate, positive association with angiographic severity: Spearman’s ρ = 0.46, p = .004. This indicates that higher homocysteine levels tend to accompany higher Gensini scores, accounting for roughly 21% of the variance in severity (ρ² ≈ 0.21). A Fisher z–based 95% confidence interval for ρ was approximately 0.16 to 0.68, supporting a non-trivial monotonic relationship. Given the expected right-skew of Gensini scores, the use of Spearman’s rho is appropriate; the finding complements the multivariable results, suggesting that homocysteine relates not only to the presence of CAD but also to its burden among affected CKD patients (Table 4). Table 5. Multivariable Logistic Regression for Predictors of CAD in CKD Patients Variable Adjusted OR (95% CI) p-value Age (per 10-year increase) 1.32 (0.98–1.77) 0.07 Male sex 1.41 (0.58–3.42) 0.45 Diabetes mellitus 2.08 (0.88–4.95) 0.09 Hypertension 1.36 (0.54–3.40) 0.52 LDL-C (per 10 mg/dL increase) 1.11 (0.96–1.29) 0.15 eGFR (per 5 mL/min/1.73 m² decrease) 1.19 (1.02–1.38) 0.02* hs-CRP (per 1 mg/L increase) 1.16 (0.99–1.36) 0.06 Vitamin B12 (per 100 pg/mL increase) 0.89 (0.72–1.10) 0.28 Folate (per 1 ng/mL increase) 0.93 (0.80–1.07) 0.30 Serum homocysteine (per 5 µmol/L increase) 1.42 (1.12–1.79) 0.003* After adjusting for the listed covariates, serum homocysteine remained an independentpredictorofCAD:each5 µmol/L increase was associated with 42% higher odds of CAD (OR 1.42, 95% CI 1.12–1.79, p=0.003).Forcontext, a 10 µmol/L difference (e.g., 15 vs 25 µmol/L) corresponds to roughly doubling the odds (1.42² ≈2.02). Lower eGFR was also independently related to CAD; every 5 mL/min/1.73 m² decreaseincreasedthe odds by 19% (OR 1.19, 95% CI 1.02–1.38, p = 0.02), so a 15 mL/min drop implies about 1.69× higher odds (1.19³ ≈ 1.69). hs-CRP (p = 0.06), age (p = 0.07), and diabetes (p = 0.09) showed suggestive trends but were not statistically significant at the 0.05 level in this sample. Sex, hypertension, LDL-C, vitamin B12, and folate were not independently associated with CAD after adjustment. Overall, the model supports homocysteine asan independent risk marker of CAD in CKD, above and beyond kidney function, inflammation, and vitamin status (Table 5). Table 6. Multivariable Linear Regression for Predictors of Gensini Score (log-transformed) in CAD-positive CKD Patients (n=38) Variable β Coefficient (95% CI) p-value Age (per 10-year increase) 0.08 (−0.02 to 0.18) 0.12 Male sex 0.11 (−0.07 to 0.29) 0.23 Diabetes mellitus 0.15 (−0.04 to 0.34) 0.11 Hypertension 0.06 (−0.12 to 0.24) 0.49 LDL-C (per 10 mg/dL increase) 0.04 (−0.01 to 0.09) 0.10 eGFR (per 5 mL/min/1.73 m² decrease) 0.07 (0.01 to 0.13) 0.03* hs-CRP (per 1 mg/L increase) 0.05 (0.00 to 0.10) 0.048* Vitamin B12 (per 100 pg/mL increase) −0.03 (−0.09 to 0.02) 0.22 Folate (per 1 ng/mL increase) −0.02 (−0.05 to 0.01) 0.18 Serum homocysteine (per 5 µmol/L increase) 0.12 (0.05 to 0.20) 0.002* *Statistically significant at p < 0.05 The outcome was log-transformed Gensini score, so coefficients reflect proportional changes in severity. Serum homocysteine was an independent predictor: each 5 µmol/L increase was associated with about a 12% higher Gensini score (β = 0.12, 95% CI 0.05–0.20, p = 0.002). For context, a 10 µmol/L higher level corresponds to ~27% higher predicted severity. Lower eGFR also related to greater severity: every 5 mL/min/1.73 m² decrease predicted ~7% higher Gensini (β = 0.07, p = 0.03). hs-CRP showed a small but significant association: ~5% higher per 1 mg/L (β = 0.05, p = 0.048). Other covariates trended in expected directions but were not significant in this sample (e.g., age ~8% per 10 years, diabetes ~16% higher, LDL-C ~4% per 10 mg/dL; all p ≥ 0.10). Vitamin B12 and folate had modest inverse, non-significant coefficients. Overall, after adjustment, homocysteine, kidney function, and inflammation were the main correlates of angiographic severity in CAD-positive CKD patients (Table 6).

In this single-centre cohort of non-dialysis CKD patients (n=75), serum homocysteine (Hcy) levels were higher in participants with angiographically proven CAD than in those without CAD, and Hcy showed a moderate, independent association with both CAD presence and severity (per 5 µmol/L increase: adjusted OR ~1.42 for CAD; β~0.12 for log-Gensini). These findings align with the long-standing biological plausibility that hyperhomocysteinaemia promotes atherothrombosis through endothelial dysfunction, oxidative stress, and smooth-muscle proliferation mechanisms repeatedly described in CKD and general populations (10). Our stage-wise analysis also demonstrated a graded rise in Hcy as eGFR declined, consistent with impaired renal clearance and altered one-carbon metabolism in CKD (2). Comparative data from prior clinical studies support our direction and magnitude of association. Shenoy et al. reported significantly higher fasting Hcy among CAD cases versus controls and a positive relation with angiographic burden, broadly mirroring our CAD+/CAD– contrast and Gensini correlation (11). Karadeniz et al. likewise observed that hyperhomocysteinaemia predicted greater CAD severity, reinforcing the gradient we observed across tertiles and per-unit increases (12). More recently, an umbrella review concluded that higher Hcy is generally associated with CAD, although overall certainty was limited by observational design and heterogeneity—points that resonate with our own study’s design constraints (5). At the same time, randomised trials and meta-analyses in CKD caution against assuming causality or therapeutic benefit from Hcy lowering alone. The HOST trial (high-dose folate/B-vitamins in CKD/ESRD) reduced Hcy biochemically but did not lower mortality or major vascular events; large meta-analyses have echoed this neutral effect on cardiovascular endpoints in kidney disease (8). These interventional results, together with cohort data showing no clear link to mortality in some CKD settings (e.g., MDRD), suggest that Hcy may behave more as a risk marker that tracks with the uraemic milieu and inflammation than as an isolated, modifiable driver of events (13). Our multivariable models where eGFR decline and hs-CRP also associated with CAD burden fit this “clustered risk” interpretation. Clinical implications follow from this synthesis. First, in CKD clinics where invasive angiography is contemplated, markedly elevated Hcy (especially alongside inflammation and lower eGFR) may flag a higher likelihood of obstructive/multivessel CAD; however, Hcy should complement not replace established risk assessment. Second, routine pharmacologic Hcy-lowering to prevent CAD in CKD is not supported by trial evidence; instead, comprehensive risk modification (BP, lipids, glycaemia, smoking cessation) remains paramount (14). Finally, emerging ratios (e.g., Hcy/ApoA-I) and multi-biomarker panels are being explored for CAD risk stratification; though promising, they require validation in CKD cohorts before adoption (15). Strengths and limitations- Strengths include angiographic CAD adjudication with Gensini scoring and adjustment for vitamin status (B12, folate) and inflammatory burden. Limitations include the cross-sectional design (no causal inference), modest sample size from a single department, and potential residual confounding (dietary folate exposure, genetic polymorphisms such as MTHFR). Pre-analytical handling of Hcy was standardised, but enzymatic immunoassay variability across platforms may limit generalisability.

In CKD patients evaluated at our centre, higher serum homocysteine was independently associated with the presence and angiographic severity of CAD and increased progressively with CKD stage. These results support the role of Hcy as a risk marker of atherosclerotic burden within the broader CKD risk milieu, while trial evidence continues to argue against Hcy-targeted vitamin therapy for cardiovascular prevention. Larger, longitudinal CKD cohorts—ideally incorporating multi-biomarker and imaging phenotypes—are needed to clarify prognostic utility and refine risk stratification.

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