José Luño

Effect of Allopurinol in Chronic Kidney Disease Progression and Cardiovascular Risk

BACKGROUND AND OBJECTIVES Hyperuricemia is associated with hypertension, inflammation, renal disease progression, and cardiovascular disease. However, no data are available regarding the effect of allopurinol in patients with chronic kidney disease. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We conducted a prospective, randomized trial of 113 patients with estimated GFR (eGFR) <60 ml/min. Patients were randomly assigned to treatment with allopurinol 100 mg/d (n = 57) or to continue the usual therapy (n = 56). Clinical, biochemical, and inflammatory parameters were measured at baseline and at 6, 12, and 24 months of treatment. The objectives of study were: (1) renal disease progression; (2) cardiovascular events; and (3) hospitalizations of any causes. RESULTS Serum uric acid and C-reactive protein levels were significantly decreased in subjects treated with allopurinol. In the control group, eGFR decreased 3.3 +/- 1.2 ml/min per 1.73 m(2), and in the allopurinol group, eGFR increased 1.3 +/- 1.3 ml/min per 1.73 m(2) after 24 months. Allopurinol treatment slowed down renal disease progression independently of age, gender, diabetes, C-reactive protein, albuminuria, and renin-angiotensin system blockers use. After a mean follow-up time of 23.4 +/- 7.8 months, 22 patients suffered a cardiovascular event. Diabetes mellitus, previous coronary heart disease, and C-reactive protein levels increased cardiovascular risk. Allopurinol treatment reduces risk of cardiovascular events in 71% compared with standard therapy. CONCLUSIONS Allopurinol decreases C-reactive protein and slows down the progression of renal disease in patients with chronic kidney disease. In addition, allopurinol reduces cardiovascular and hospitalization risk in these subjects.

Oxidative stress and inflammation, a link between chronic kidney disease and cardiovascular disease.

Patients with chronic kidney disease (CKD) show a high cardiovascular morbidity and mortality. This seems to be consequence of the cardiovascular risk factor clustering in CKD patients. Non traditional risk factors such as oxidative stress and inflammation are also far more prevalent in this population than in normal subjects. Renal disease is associated with a graded increase in oxidative stress markers even in early CKD. This could be consequence of an increase in reactive oxygen species as well as a decrease in antioxidant defence. This oxidative stress can accelerate renal injury progression. Inflammatory markers such as C reactive protein and cytokines increase with renal function deterioration suggesting that CKD is a low-grade inflammatory process. In fact, inflammation facilitates renal function deterioration. Several factors can be involved in triggering the inflammatory process including oxidative stress. Statin administration is accompanied by risk reduction in all major vascular events in patients with CKD that are considered high-risk patients. These beneficial effects seem to be consequence of not only their hypolipidemic effect but especially their pleitropic actions that involve modulation of oxidative stress and inflammation.

Allopurinol and Progression of CKD and Cardiovascular Events: Long-term Follow-up of a Randomized Clinical Trial

BACKGROUND Asymptomatic hyperuricemia increases renal and cardiovascular (CV) risk. We previously conducted a 2-year, single-blind, randomized, controlled trial of allopurinol treatment that showed improved estimated glomerular filtration rate and reduced CV risk. STUDY DESIGN Post hoc analysis of a long-term follow-up after completion of the 2-year trial. SETTING & PARTICIPANTS 113 participants (57 in the allopurinol group and 56 in the control group) initially followed up for 2 years and 107 participants followed up to 5 additional years. INTERVENTION Continuation of allopurinol treatment, 100mg/d, or standard treatment. OUTCOME Renal event (defined as starting dialysis therapy and/or doubling serum creatinine and/or ≥50% decrease in estimated estimated glomerular filtration rate) and CV events (defined as myocardial infarction, coronary revascularization or angina pectoris, congestive heart failure, cerebrovascular disease, and peripheral vascular disease). RESULTS During initial follow-up, there were 2 renal and 7 CV events in the allopurinol group compared with 6 renal and 15 CV events in the control group. In the long-term follow-up period, 12 of 56 participants taking allopurinol stopped treatment and 10 of 51 control participants received allopurinol. During long-term follow-up, an additional 7 and 9 participants in the allopurinol group experienced a renal or CV event, respectively, and an additional 18 and 8 participants in the control group experienced a renal or CV event, respectively. Thus, during the initial and long-term follow-up (median, 84 months), 9 patients in the allopurinol group had a renal event compared with 24 patients in the control group (HR, 0.32; 95% CI, 0.15-0.69; P=0.004; adjusted for age, sex, baseline kidney function, uric acid level, and renin-angiotensin-aldosterone system blockers). Overall, 16 patients treated with allopurinol experienced CV events compared with 23 in the control group (HR, 0.43; 95% CI, 0.21-0.88; P=0.02; adjusted for age, sex, and baseline kidney function). LIMITATIONS Small sample size, single center, not double blind, post hoc follow-up and analysis. CONCLUSIONS Long-term treatment with allopurinol may slow the rate of progression of kidney disease and reduce CV risk.

Insulin Resistance, Inflammatory Biomarkers, and Adipokines in Patients with Chronic Kidney Disease: Effects of Angiotensin II Blockade

Patients with chronic kidney disease (CKD) present a high prevalence of insulin resistance (IR). Some studies suggest that angiotensin II may influence some cellular pathways that contribute to the pathogenesis of IR and stimulate the release of proinflammatory cytokines. Fifty-two patients who had stages 3 and 4 CKD and no diabetes were administered an angiotensin receptor blocker (ARB), olmesartan (40 mg), for 16 wk. Before and after ARB treatment, metabolic and inflammatory parameters and adipokines were measured. IR was calculated by Homeostasis Model Assessment (HOMA) index. Baseline data were compared with data that were obtained from 25 healthy control individuals of similar age and normal renal function. Compared with control subjects, patients with CKD presented significantly higher BP and waist circumference, higher triglycerides and lower HDL levels, higher insulin levels, and higher mean HOMA index (6.0 +/- 2.7 versus 2.9 +/- 2.2 muU/ml x mmol/L; P < 0.001). In addition, patients with CKD had increased levels of high-sensitivity C-reactive protein, TNF-alpha, and IL-6. In patients with CKD, leptin was positively correlated to abdominal obesity, insulin levels, and IL-6, and adiponectin was inversely correlated to abdominal obesity and insulin levels. Olmesartan treatment resulted in a significant decrease of BP, urinary protein excretion, plasma glucose (99 +/- 16 versus 92 +/- 14 mg/dl; P < 0.05), insulin (23.1 +/- 8.8 versus 19.9 +/- 9; P < 0.05), HOMA index (6.0 +/- 2.7 versus 4.7 +/- 2.8; P < 0.05), and glycated hemoglobin (5.33 +/- 0.58 versus 4.85 +/- 0.81%; P < 0.01). At the same time, there was a significant reduction of high-sensitivity C-reactive protein levels, from 4.45 mg/L (2.45 to 9.00) to 3.55 mg/L (1.80 to 5.40; P < 0.05) and fibrinogen (412 +/- 100 versus 370 +/- 105 mg/dl; P < 0.05). There were no significant differences in adipokine levels after olmesartan treatment. These data demonstrate that patients with CKD have a high prevalence of IR, metabolic syndrome, and chronic inflammation and that the administration of the ARB olmesartan improves IR and inflammation markers in these patients. Plasma adipokine levels that are related to several metabolic risk factors in patients with CKD were not modified by ARB therapy.

25 (OH) Vitamin D Levels and Renal Disease Progression in Patients with Type 2 Diabetic Nephropathy and Blockade of the Renin-Angiotensin System

BACKGROUND AND OBJECTIVES Experimental studies show that 25 (OH) vitamin D is a suppressor of renin biosynthesis and that vitamin D deficiency has been associated with CKD progression. Patients with type II diabetes and CKD have an exceptionally high rate of severe 25 (OH) vitamin D deficiency; however, it is not known whether this deficiency is a risk factor for progression of diabetic nephropathy. This study aimed to investigate whether there is an association of 25 (OH) vitamin D deficiency with disease progression in type II diabetic nephropathy. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS 25 (OH) vitamin D levels were measured at baseline and 4 and 12 months in 103 patients included in a multicenter randomized controlled trial to compare the efficacy of combining an angiotensin-converting enzyme inhibitor and an angiotensin receptor blocker with the efficacy of each drug in monotherapy to slow progression of established diabetic nephropathy during 2006-2011. The primary composite endpoint was a >50% increase in baseline serum creatinine, ESRD, or death. All study participants were included in the analysis. RESULTS Fifty-three patients (51.5%) had 25 (OH) vitamin D deficiency (<15 ng/ml). After a median follow-up of 32 months, the endpoint was reached by 23 patients with deficiency (43.4%) and 8 patients without (16%). Multivariate Cox regression analysis adjusted for urinary protein/creatinine ratio, estimated GFR, and baseline aldosterone showed that 25 (OH) vitamin D deficiency was associated with the primary endpoint (hazard ratio, 2.88; 95% confidence interval, 1.84 to 7.67; P=0.04). CONCLUSIONS These results show that 25 (OH) vitamin D deficiency is independently associated with a higher risk of the composite outcome in patients with type II diabetic nephropathy.

Effect of dual blockade of the renin-angiotensin system on the progression of type 2 diabetic nephropathy: a randomized trial.

BACKGROUND Blockade of the renin-angiotensin system with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers has been shown to lessen the rate of decrease in glomerular filtration rate in patients with diabetic nephropathy. STUDY DESIGN A multicenter open-label randomized controlled trial to compare the efficacy of combining the angiotensin-converting enzyme inhibitor lisinopril and the angiotensin II receptor blocker irbesartan with that of each drug in monotherapy (at both high and equipotent doses) in slowing the progression of type 2 diabetic nephropathy. SETTING & POPULATION 133 patients with type 2 diabetic nephropathy (age, 66 ± 8 years; 76% men) from 17 centers in Spain. INTERVENTION Patients were randomly assigned (1:1:2) to lisinopril (n = 35), irbesartan (n = 28), or the combination of both (n = 70). OUTCOMES The primary composite outcome was a >50% increase in baseline serum creatinine level, end-stage renal disease, or death. RESULTS Baseline values for mean estimated glomerular filtration rate and blood pressure were 49 ± 21 mL/min/1.73 m(2) and 153 ± 19/81 ± 11 mm Hg. Mean geometric baseline proteinuria was protein excretion of 1.32 (95% CI, 1.10-1.62) g/g creatinine. After a median follow-up of 32 months, 21 (30%) patients in the combination group, 10 (29%) in the lisinopril group, and 8 (29%) in the irbesartan group reached the primary outcome. HRs were 0.96 (95% CI, 0.44-2.05; P = 0.9) and 0.90 (95% CI, 0.39-2.02; P = 0.8) for the combination versus the lisinopril and irbesartan groups, respectively. There were no significant differences in proteinuria reduction or blood pressure control between groups. The number of adverse events, including hyperkalemia, was similar in all 3 groups. LIMITATIONS The study was not double blind. The sample size studied was small. CONCLUSIONS We were unable to show a benefit of the combination of lisinopril and irbesartan compared to either agent alone at optimal high doses on the risk of progression of type 2 diabetic nephropathy.

Effects of pentoxifylline on inflammatory parameters in chronic kidney disease patients: a randomized trial.

BACKGROUND Pentoxifylline (PTF) is a potential therapeutic agent in chronic kidney disease due to its antiinflammatory and antiproteinuric effects that may influence the progression of renal disease. SUBJECTS AND METHODS We conducted a prospective randomized trial of 91 patients with estimated glomerular filtration rate (eGFR) <60 ml/min, calculated with 4-variable Modification of Diet in Renal Disease (MDRD-4) Study equation. Patients were randomly assigned to treatment with PTF 400 mg (twice a day) (n=46) or to continue their usual therapy (n=45). Clinical, biochemical and inflammatory parameters were measured at baseline, and at 6 and 12 months of treatment. The objective of the study was to analyze the effect of PTF treatment on inflammatory markers and secondarily the effect on renal disease progression. RESULTS Baseline characteristics were similar in the 2 groups. High-sensitivity C-reactive protein (hs-CRP), serum fibrinogen and TNF-alpha decreased significantly in patients treated with PTF in comparison with the control group at 12 months (p=0.002, p=0.001 and p=0.000, respectively). Median urinary albumin excretion did not decrease with PTF treatment. In the PTF group, there was no significant change in eGFR after 12 months (from 42.3 ± 10.2 to 44.7 ± 11.3 ml/min per 1.73 m(2)), whereas in the control group there was a worsening by the end of the study (from 40.1 ± 12.4 to 35.7 ± 13.4 ml/min per 1.73 m(2)) (p=0.000 between groups). CONCLUSIONS PTF treatment decreases inflammatory markers in chronic kidney disease and stabilizes renal function.

Metformin-associated acute kidney injury and lactic acidosis.

Objectives. Metformin is the preferred oral antidiabetic agent for type 2 diabetes. Lactic acidosis is described as a rare complication, usually during an acute kidney injury (AKI). Material and Methods. We conducted a prospective observational study of metformin-associated AKI cases during four years. 29 cases were identified. Previous renal function, clinical data, and outcomes were recorded. Results. An episode of acute gastroenteritis precipitated the event in 26 cases. Three developed a septic shock. Three patients died, the only related factor being liver dysfunction. More severe metabolic acidosis hyperkalemia and anemia were associated with higher probabilities of RRT requirement. We could not find any relationship between previous renal dysfunction and the outcome of the AKI. Conclusions. AKI associated to an episode of volume depletion due to gastrointestinal losses is a serious complication in type 2 diabetic patients on metformin. Previous renal dysfunction (mild-to-moderate CKD) has no influence on the severity or outcome.

Dual Blockade of the Renin-Angiotensin System in the Progression of Renal Disease: The Need for More Clinical Trials

There is clear evidence that pharmacologic blockade of the renin-angiotensin system (RAS) with angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) reduces proteinuria and slows the progression of renal disease in diabetic and nondiabetic nephropathies, a beneficial effect that is not related to BP control. Some patients exhibit a significant beneficial response, whereas others do not. The absence of response may be explained by the incomplete blockade of the RAS obtained with ACEI. In the search of new alternatives that could improve the antiproteinuric and nephroprotective effects of RAS blockers, the association of ACEI and ARB might prove useful. ARB produces a complete blockade of the RAS. Several studies have shown a more marked antiproteinuric effect of the dual blockade of the RAS versus ACEI or ARB alone. A recent study also demonstrated that this more marked antiproteinuric effect is associated with less progression of renal disease in primary nondiabetic nephropathies despite a similar effect on BP. Until now, there has not been any reference to a beneficial effect on progression of the dual blockade in type 2 diabetic nephropathy, which is the most frequent cause of ESRD. A multicenter, prospective, open, active-controlled, and parallel-group trial was designed to compare the effects of an ACE inhibitor versus an ARB or its combination on renal disease progression, proteinuria, and cardiovascular events in type 2 diabetic nephropathy.

The reno-protective effect of the dual blockade of the renin angiotensin system (RAS).

Hypertension and proteinuria are risk factors for renal disease progression. There is clear evidence that pharmacological blockade of the RAS with angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) reduces proteinuria and slows down the progression of renal disease in diabetic and non diabetic nephropathies, a beneficial effect not related to blood pressure control. However, not all patients respond similarly to these treatments. Some patients exhibit a significant beneficial response while others do not. The absence of response may be explained by the incomplete blockade of the RAS obtained with ACEI, which are unable to block completely the formation of AII, some generation of AII is produced via other non ACE pathways. In the search of new alternatives that could improve the antiproteinuric and nephroprotective effects of RAS blockers, the association of ACEI and ARB might prove to be useful. ARB produces a complete blockade of the RAS and stimulates the vasodilating and non-proliferative actions of AII via the AT-2 receptor. Furthermore, ACE inhibitors but not ARB; inhibit the metabolism of kinins, which increases the level of bradykinin, a potent vasodilator. Recently, several authors have shown a more marked antiproteinuric effect of the dual blockade of the RAS versus ACEI or ARB alone in spite of a similar effect on blood pressure. A recent study also has demonstrated that this more marked antiproteinuric effect is associated with a less progression of renal disease in primary, non diabetic nephropathies. Furthermore, at least two studies have shown that, treatment with ARB postpones end-stage renal disease and reduces the rate of decline in renal function in patients with type 2 diabetes and nephropathy, but until now, there is not any clear evidence of a superior beneficial effect of dual blockade versus maximal recommended dose of ARB regarding renal progression in type 2 diabetic nephropathy, which is the most frequent cause of end stage renal disease. Long-term clinical trials are needed and encouraged to further establish the significant role of dual blockade in renal protection particularly in diabetic nephropathy.