Prevalence, risk factors and predicted risk of cardiac events in chronic kidney disease of uncertain aetiology in Sri Lanka: A tubular interstitial nephropathy.

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in patients with 'traditional' chronic kidney disease (CKD). However, chronic kidney disease of uncertain aetiology (CKDu), a tubular interstitial nephropathy is typically minimally proteinuric without high rates of associated hypertension or vascular disease and it is unknown if the rates of CVD are similar. This study aimed to identify the prevalence and the risk of CVD in patients with CKDu. This cross-sectional study included patients with confirmed CKDu who were attending two renal clinics in CKDu endemic-area. A detailed medical history, blood pressure, electrocardiogram (resting and six minutes vigorous walking), echocardiograms, appropriate laboratory parameters and medical record reviews were used to collect data at baseline. The WHO/Pan American Health Organization, cardiovascular risk calculator was employed to determine the future risk of CVD. The clinics had recorded 132 number of patients with CKDu, of these 119 consented to participation in the study. The mean age was 52 (± 9.5) years and mean eGFR was 51.1 (± 27.61); a majority (81.5% (n = 97)) were males. Thirty-four patients (28.6%) had evidence of ischaemic heart disease (IHD). Troponin-I (p = 0.02), Age >50 years (p = 0.01) and hyperuricemia (p = 0.01) were significantly associated with IHD in CKDu. Left ventricular hypertrophy was reported in 20.2% (n = 24). According to the risk calculator, 97% of the enrolled patients were at low risk (<10%) for experiencing a cardiovascular event within the next 10 years. Patients with CKDu have low prevalence and risk for CVD, implying that a majority are likely to survive to reach end-stage kidney disease. Our findings highlight the need for developing strategies to minimize the progression of CKDu to end-stage renal disease.

An Analysis of Rate of Progression and Associated Risk Factors of Chronic Kidney Disease of Uncertain Etiology in Sri Lanka.

Chronic kidney disease of uncertain etiology (CKD-u) is an important public health issue in Sri Lanka and around the world, but published evidence of the progression of this disease is scanty. Our aim is to analyze the progression patterns and the associated risk factors of definite and probable CKD-u cases. This observational study was based on records of CKD-u cohort from 2005-14 at Girandurukotte, an endemic area for CKD-u in Uva Province, Sri Lanka. Data (rate of progression, survival, and risk factors) were analyzed using R statistical software. CKD-u cases (379) were included in analyses based on the adequacy of variables. Mean age was 53 years, male-to-female ratio of 2.5:1, and smoking were significant risk factors (P <0.10) for CKD-u progression. Males had 2.3 times hazard for CKD-u survival than females, and males who smoked had 2.57 times risk of CKD-u progression than nonsmoking males. Faster eGFR decline rate of >5 mL/min/1.73 m2/year have been identified in 25% of the sample (n = 100); this group is significantly younger than the slower progression group (mean age 46 years) and was at an early stage at the time of presentation (mean eGFR 76.02). CKD-u progression was not equal in all patients but faster in young people who presented at earlier stages. Continuous exposure to environmental risk factors may influence the rate of progression. Females have higher CKD-u survival rates than males. Tobacco smoking was associated with a lower survival of CKD-u but could be a proxy indicative of other exposures.

Correction: Evaluation of biochemical profile of Chronic Kidney Disease of uncertain etiology in Sri Lanka.

[This corrects the article DOI: 10.1371/journal.pone.0232522.].

Evaluation of biochemical profile of Chronic Kidney Disease of uncertain etiology in Sri Lanka.

Chronic Kidney Disease of uncertain etiology (CKDu) is an endemic, disease that mostly affects young agricultural workers in the rural dry zone of Sri Lanka. This study was designed to identify specific biochemical manifestations of CKDu cases. All (119) non-dialysis definite CKDu patients in Girandurukotte and Wilgamuwa were selected. Blood and urine samples were collected and measured biochemical parameters. All analyses were performed in IBM SPSS statistics version 23 (IBM Corp, USA). The median blood pressure was normal though nearly half of the patients (45.4%) who were in the advanced stages (Stage 3b, 4 and 5) of CKDu. Patients without a history of hypertension before the diagnosis of CKDu (100%) and minimal proteinuria (26%) are similar to the previous findings. Patients without a history of diabetes before the CKDu diagnosis had high percentages of diabetes (15.7%) and pre-diabetes (59.8%) and hence indicated the possibility of uremia induced impaired glucose intolerance in the rural areas of the country. There were 62.2% patients who had low vitamin D and only a minority had evidence of bone mineral diseases. Out of liver disease markers serum glutamic pyruvic transaminases (SGPT), serum glutamic oxaloacetic transaminases (SGOT), gamma-glutamyl transferase (GGT), and Lactic acid degydrogenase (LDH) had an inverse correlation with the advancement of the disease indicating subclinical liver disease. Osmolality in serum and urine showed a discrepancy despite > 50% of CKDu patients had increased their serum osmolality. The current study supports most of the previously described manifestations of CKDu. Moreover, some specific patterns have been identified which need to be validated in a larger group.

Pilot Study of Renal Urinary Biomarkers for Diagnosis of CKD of Uncertain Etiology.

INTRODUCTION: Chronic kidney disease of uncertain etiology (CKDu), an emerging chronic kidney disease (CKD) subtype, contributes to significant morbidity and mortality in certain tropical countries. Although several indicators of CKDu have been previously suggested, sensitive and specific tests to detect early disease or predict disease progression are currently unavailable. This study focused on evaluating 8 renal urinary markers, namely neutrophil gelatinase-associated lipocalin (NGAL), Kidney Injury Molecule-1 (KIM1), cystatin C (CST3), beta 2 microglobulin (B2M), osteopontin (OPN), alpha 1 microglobulin (A1M), tissue inhibitor of metalloproteinase 1 (TIMP1), and retinol binding protein 4 (RBP4), with the hypothesis that these have distinct expression patterns in patients with CKDu. METHODS: A cross-sectional study was conducted with 5 study groups comprising subjects from CKDu, endemic CKD, nonendemic CKD, and endemic healthy and nonendemic healthy controls. The urinary levels of the 8 selected renal biomarkers were quantified using multiplex biomarker assay, and the data were subjected to systematic analysis using logistic regression algorithm aiming to extract the best marker combination that could distinctly identify the disease groups noninvasively from the healthy controls. RESULTS: A 3-marker signature panel comprising A1M, KIM1, and RBP4 was identified to represent the best minimum marker combination for differentiating all CKD categories, including CKDu, from healthy controls with an overall sensitivity of ≥0.867 and specificity ≥0.765. The marker combination comprising OPN, KIM1, and RBP4 showed high predictive performance for distinguishing patients with CKDu from patients with CKD with both sensitivity and specificity ≥0.93, which was superior to any existing noninvasive indicator. CONCLUSION: In all, our systematic evaluation of urinary markers previously linked to CKD, in general, allowed identification of exclusive marker panel combination for early diagnosis and confirmation of CKDu.

Snap shot view on anaemia in chronic kidney disease of uncertain aetiology.

AIM: Anaemia is a well-known complication of chronic kidney disease but there are no published studies on the pattern of anaemia in chronic kidney disease of uncertain aetiology (CKDu). This study aims to find out the prevalence, causes and associations of anaemia in CKDu to identify any unique features which are different from already described anaemia in chronic kidney disease. METHOD: All (119) biopsy-confirmed CKDu patients in two endemic clinics (Girandurukotte and Wilgamuwa) were selected as cases. Blood samples (10 mL) were collected from the peripheral veins into Potassium-Ethylenediaminetetraacetic acid (K-EDTA) tubes, plain tubes and Na-citrated tubes. Serum was separated immediately by centrifugation at 3000 rpm for 10 min. Spot urine samples were collected into empty, sterile, polypropylene urine containers. All analyses were performed in IBM spss statistics version 23 (IBM Corp, Armonk, New York). RESULTS: The overall prevalence of anaemia in 119 non-dialysis CKDu patients was 72.3% with the highest prevalence seen in females compared to males (P < 0.001). The prevalence of anaemia in CKDu patients with progression to renal failure was 66.7% - stage 1, 60% - stage 2, 50% - stage 3a, 95% - stage 3b, 79.2% - stage 4 and 100% - stage 5 (P = 0.005). Of CKDu patients, 44.3% had anaemia of chronic disease with iron deficiency. CKDu patients with anaemia had a high inflammatory score were seen in both early and late stages of CKDu. There were a similar proportion of patients with both early and late CKDu having unexplained anaemia. CONCLUSION: The current study showed a significant association of anaemia with disease severity among CKDu patients. Iron deficiency is a crucial aetiology factor of anaemia in CKDu and inflammation likely to effects adversely on anaemia of CKDu.