Associations of Fenofibrate Therapy With Incidence and Progression of CKD in Patients With Type 2 Diabetes

Introduction

Abnormalities in lipid metabolism may contribute to the development and progression of chronic kidney disease (CKD) in patients with type 2 diabetes. Fenofibrate induces early and reversible reduction in estimated glomerular filtration rate (eGFR), but it may have protective effects on microvascular complications of diabetes. We hypothesized that randomization to fenofibrate versus placebo would be associated with beneficial long-term effects on kidney outcomes in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial participants.

Methods

We conducted a post hoc analysis in the ACCORD Lipid Trial to examine the association of randomization to fenofibrate versus placebo with change in eGFR and with time-to-development of microalbuminuria, macroalbuminuria, CKD, and kidney failure.

Results

We analyzed 2636 participants in the fenofibrate arm and 2632 in the placebo arm. During a median follow-up of 4 years, treatment with fenofibrate was associated with lower rate of eGFR decline (−0.28 ml/min per 1.73 m² per year in the fenofibrate group vs. −1.25 ml/min per 1.73 m² per year in the placebo group, P < 0.01) and with lower incidence of microalbuminuria (hazard ratio [HR] 0.56, 95% confidence interval [CI] 0.43–0.72, P < 0.001) and macroalbuminuria (HR 0.72, 95% CI 0.57–0.91, P < 0.001). There was no difference in incidence of CKD (HR 0.92, 95% CI 0.74–1.15, P = 0.46) and/or kidney failure (HR 0.95, 95% CI 0.68–1.33, P = 0.76).

Conclusion

Compared with placebo, randomization to fenofibrate was associated with lower rates of incident albuminuria and a slower eGFR decline, but no difference in incidence of CKD or kidney failure in ACCORD participants.

Anatomic and physiologic changes of the aging kidney

Aging is associated with structural and functional changes in the kidney. Structural changes include glomerulosclerosis, thickening of the basement membrane, increase in mesangial matrix, tubulointerstitial fibrosis and arteriosclerosis. Glomerular filtration rate is maintained until the fourth decade of life, after which it declines. Parallel reductions in renal blood flow occur with redistribution of blood flow from the cortex to the medulla. Other functional changes include an increase in glomerular basement permeability and decreased ability to dilute or concentrate urine.

Variable clinical presentation of an MUC1 mutation causing medullary cystic kidney disease type 1

BACKGROUND AND OBJECTIVES

The genetic cause of medullary cystic kidney disease type 1 was recently identified as a cytosine insertion in the variable number of tandem repeat region of MUC1 encoding mucoprotein-1 (MUC1), a protein that is present in skin, breast, and lung tissue, the gastrointestinal tract, and the distal tubules of the kidney. The purpose of this investigation was to analyze the clinical characteristics of families and individuals with this mutation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Families with autosomal dominant interstitial kidney disease were referred for genetic analysis over a 14-year period. Families without UMOD or REN mutations prospectively underwent genotyping for the presence of the MUC1 mutation. Clinical characteristics were retrospectively evaluated in individuals with the MUC1 mutation and historically affected individuals (persons who were both related to genetically affected individuals in such a way that ensured that they could be genetically affected and had a history of CKD stage IV or kidney failure resulting in death, dialysis, or transplantation).

RESULTS

Twenty-four families were identified with the MUC1 mutation. Of 186 family members undergoing MUC1 mutational analysis, the mutation was identified in 95 individuals, 91 individuals did not have the mutation, and111 individuals were identified as historically affected. Individuals with the MUC1 mutation suffered from chronic kidney failure with a widely variable age of onset of end stage kidney disease ranging from 16 to >80 years. Urinalyses revealed minimal protein and no blood. Ultrasounds of 35 individuals showed no medullary cysts. There were no clinical manifestations of the MUC1 mutation detected in the breasts, skin, respiratory system, or gastrointestinal tract.

CONCLUSION

MUC1 mutation results in progressive chronic kidney failure with a bland urinary sediment. The age of onset of end stage kidney disease is highly variable, suggesting that gene-gene or gene-environment interactions contribute to phenotypic variability.

Clinical performance and skill retention after simulation-based education for nephrology fellows

We previously demonstrated that simulation-based education (SBE) improved temporary hemodialysis catheter (THDC) insertion skills by nephrology fellows. SBE, featuring deliberate practice and rigorous achievement standards, was a powerful method to enhance THDC insertion skills in nephrology fellows. However, experts have called for further research to evaluate skill transfer from the simulated environment to actual clinical care and skill retention. This is a prospective observational cohort study of THDC insertion skills. Twelve nephrology fellows from three academic centers in Chicago were evaluated using a skills checklist from July 2008 to June 2009. Simulator-trained fellows were tested after the SBE intervention and expected to meet or exceed a minimum passing score (MPS) set by an expert panel. To assess transfer of skill to clinical care, three simulator-trained fellows were assessed at 6 months on actual patient THDC insertions using the checklist. To assess retention of skill, 11 of 12 simulator-trained fellows were reassessed at 1 year using the checklist and central venous catheter simulator. Outcomes were determined by THDC insertion skill performance. Simulator-trained fellows scored similarly during 6-month THDC insertions on actual patients and immediate posttest (M = 86.2%, SD = 22.3% vs. M = 93.5%, SD = 5.3%, p = 0.32). However, 1 year after SBE, simulated THDC insertion scores were significantly lower than at immediate posttest (M = 73.4%, SD = 22.2% vs. M = 93.5%, SD = 5.3%, p = 0.01). Our results show that nephrology fellows who completed SBE displayed high levels of performance during THDC insertions on actual patients 6 months later. At 1 year, there was statistically significant skills decay. We recommend booster training at 6 months.

Horseshoe kidney in an 80 year old with chronic kidney disease

This image illustrates a horseshoe kidney from an elderly man that was being evaluated for chronic kidney disease associated with diabetes. Horseshoe kidney is the most common renal fusion abnormality, with an incidence of 1/400 worldwide and a male-to-female ratio of 2:1 and is not a cause of impaired kidney function. One theory of the abnormal fusion of the kidneys is that the metanephric blastemas close together before renal capsule maturation, resulting in fusion. The normal embryonic ascent of the fused kidney is disrupted by the inferior mesenteric artery, leaving the adult horseshoe kidney in a lower position than normal. About 90% of the time, the lower poles are fused and the excretory renal units and ureters are maintained separately.

Lithium-associated kidney microcysts

Long-term lithium therapy is associated with impairment in concentrating ability and, occasionally, progression to advanced chronic kidney disease from tubulointerstitial nephropathy. Biopsy findings in patients with lithium-induced chronic tubulointerstitial nephropathy include tubular atrophy and interstitial fibrosis interspersed with tubular cysts and dilatations. Recent studies have shown that cysts are seen in 33-62.5% of the patients undergoing lithium therapy. MR imaging is highly capable of defining renal morphological features and has been demonstrated to be superior to US and CT scan for the visualization of small renal cysts. The microcysts are found in both cortex and medulla, particularly in the regions with extensive atrophy and fibrosis, and can be multiple and bilateral. They tend to be sparse and do not normally exceed 1-2 mm in diameter. The renal microcysts in the image here reported are subtle, but consistent with lithium-induced chronic nephropathy. An MRI of the kidneys provides noninvasive evidence that strengthens the diagnosis of lithium-induced nephropathy.

Comparison of the Flow Properties of Aqueous Suspension Corticosteroid Nasal Sprays Under Differing Sampling Conditions

Many aqueous suspension corticosteroid nasal sprays become less viscous when shaken and sprayed, then return to a more viscous state after application. This time-dependent, reversible loss of viscosity under shear (e.g., shaking or spraying) can be quantified in the rheological property of thixotropy. The flow properties of 5 corticosteroid nasal sprays were measured over a range of shear rates. The formulations tested included Nasonex, Vancenase AQ, Nasacort AQ, Rhinocort Aqua, and Flonase. The yield stress values, as well as an estimate of thixotropy, were compared by using three different sampling techniques, including one that simulated patient use (shaking for 30 sec, spraying, and immediately transferring the sample to the rheometer). The rheological properties of all products indicated that when initially shaken and dispensed, they flowed more freely, followed by recovery of viscosity that would likely inhibit the suspensions from flowing out of the nasal cavity. Under all three tested conditions, Nasonex exhibited the highest yield stress, the largest apparent initial and final viscosities, and the highest apparent thixotropy. The study protocol that simulated patient-use conditions produced the following rank order of measured thixotropy: Nasonex > Flonase > Vancenase AQ > Rhinocort Aqua > Nasacort AQ. The thixotropy of Nasonex was 3.4 to 21.4 times greater and the final viscosity was 3.2 to 17.4 times greater than the values of the other tested products.