Clinical Profile of Echocardiographically Estimated Pulmonary Hypertension in Patients with Non Dialysis-dependent Chronic Kidney Disease Stages 3-5: A Cross-sectional Study

Abstract

Introduction: Pulmonary Hypertension (PHTN) is increasingly recognised as a clinically significant complication of Chronic Kidney Disease (CKD), even before initiation of dialysis. However, the clinical profile, echocardiographic pulmonary pressure estimates, and biochemical correlates of PHTN in Non Dialysis-Dependent CKD (NDD-CKD) stages 3-5 remain incompletely characterised. Aim: To describe the clinical profile of elevated pulmonary pressures in NDD-CKD stage 3-5, estimate Pulmonary Artery Systolic Pressure (PASP) by echocardiography and to determine PHTN prevalence and severity, and explore correlations between biochemical parameters and PHTN severity. Materials and Methods: The present hospital-based crosssectional study enrolled 84 NDD-CKD stage 3-5 patients at a tertiary care centre, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth (Deemed to be University), Puducherry, India. PASP was estimated by transthoracic echocardiography and mean Pulmonary Artery Pressure (mPAP) was derived using the Chemla formula (mPAP=0.61×PASP+2). Elevated pulmonary pressure was defined as mPAP ≥20 mmHg and categorised as mild (≥20- 40 mmHg), moderate (>40-55 mmHg), or severe (>55 mmHg); values <20 mmHg were considered normal. Demographic data, co-morbidities, CKD stage, and laboratory investigations were measured. Non parametric stage-wise comparisons with Bonferroni correction, Spearman correlations, ordered-stage trend analyses, and binary logistic regression were performed using Statistical Package for the Social Sciences (SPSS) version 24.0. p-value of <0.05 was considered statistically significant. Results: Mean age was 48.18±14.07; 49 (58.3%) were male. Hypertension (HTN) was present in 70 (83.3%) participants, Diabetes Mellitus (DM) in 37 (44.0%), and smoking in 45 (53.6%). Mean mPAP was 36.29±16.68 mmHg; Elevated pulmonary pressure was present in 59 (70.2%) participants, comprising mild elevation in 20 (23.8%), moderate elevation in 24 (28.6%), and severe elevation in 15 (17.9%). mPAP increased significantly across CKD stages (p=0.006), with an increasing ordered-stage trend (p=0.0006) and rising PHTN severity (rs=0.288; p=0.007). mPAP correlated positively with serum urea (rs=0.335; p=0.001) and creatinine (rs =0.332; p=0.002), and negatively with estimated Glomerular Filtration Rate (eGFR) (rs=−0.339; p=0.001)-all surviving Bonferroni correction. HTN was an independent predictor of PHTN on both univariate (OR 4.157; 95% CI 1.263- 13.680; p=0.019) and multivariable analysis (adjusted Odds Ratio (aOR)=5.425; 95% CI=1.416-20.783; p=0.014). Conclusion: PHTN burden is high in NDD-CKD stage 3-5 and increases with declining renal function. HTN independently predicts PHTN, highlighting the importance of left-heartmediated mechanisms. Structured cardiopulmonary evaluation is warranted in advanced pre-dialysis CKD.