HIV viremia and T-cell activation differentially affect the performance of glomerular filtration rate equations based on creatinine and cystatin C

BACKGROUND

Serum creatinine and cystatin C are used as markers of glomerular filtration rate (GFR). The performance of these GFR markers relative to exogenously measured GFR (mGFR) in HIV-positive individuals is not well established.

METHODS

We assessed the performance of the chronic kidney disease epidemiology collaboration equations based on serum concentrations of creatinine (eGFRcr), cystatin C (eGFRcys) and both biomarkers combined (eGFRcr-cys) in 187 HIV-positive and 98 HIV-negative participants. Measured GFR was calculated by plasma iohexol clearance. Bias and accuracy were defined as the difference between eGFR and mGFR and the percentage of eGFR observations within 30% of mGFR, respectively. Activated CD4 and CD8 T-cells (CD38+ HLA-DR+) were measured by flow cytometry.

RESULTS

The median mGFR was >100 ml/min/1.73 m(2) in both groups. All equations tended to be less accurate in HIV-positive than in HIV-negative subjects, with eGFRcr-cys being the most accurate overall. In the HIV-positive group, eGFRcys was significantly less accurate and more biased than eGFRcr and eGFRcr_cys. Additionally eGFRcys bias and accuracy were strongly associated with use of antiretroviral therapy, HIV RNA suppression, and percentages of activated CD4 or CD8 T-cells. Hepatitis C seropositivity was associated with larger eGFRcys bias in both HIV-positive and HIV-negative groups. In contrast, eGFRcr accuracy and bias were not associated with HIV-related factors, T-cell activation, or hepatitis C.

CONCLUSIONS

The performance of eGFRcys relative to mGFR was strongly correlated with HIV treatment factors and markers of T-cell activation, which may limit its usefulness as a GFR marker in this population.

Podocyte effacement closely links to suPAR levels at time of posttransplantation focal segmental glomerulosclerosis occurrence and improves with therapy

BACKGROUND

Focal segmental glomerulosclerosis (FSGS) recurs after kidney transplantation in more than 30% of cases and can lead to allograft loss. Serum soluble urokinase-type plasminogen activator receptor (suPAR) is implicated in the pathogenesis of native and recurrent FSGS.

METHODS

We conducted a retrospective study of 25 adults with posttransplantation FSGS. We investigated the relationship between suPAR levels and podocyte changes and the impact of therapy on podocyte structure. We assessed response to therapy by improvement in proteinuria, allograft function, and resolution of histologic changes.

RESULTS

A median (interquartile range) of 15 (10-23) plasmapheresis sessions was administered; 13 of the subjects also received rituximab. Median pretreatment suPAR levels were higher among those with severe (≥75%) versus those with mild (≤25%) podocyte foot process effacement (13,030 vs. 4806 pg/mL; P=0.02). Overall, mean±SD of proteinuria improved from 5.1±3.8 to 2.1±2.8 mg/dL (P=0.003), mean podocyte effacement decreased from 57%±33% to 22%±22% (P=0.0001), estimated glomerular filtration rates increased from median (interquartile range) of 32.9 (20.6-44.2) to 39.3 (28.8-63.4; P<0.0001), and suPAR levels decreased from a median of 6.781 to 4.129 pg/mL (P=0.02) with therapy.

CONCLUSIONS

Podocyte effacement is the first pathologic manifestation of FSGS after transplantation. The degree of podocyte effacement correlates with suPAR levels at time of diagnosis. Response to therapy results in significant reduction of suPAR levels and complete or significant improvement of podocyte effacement.

Perceptions and use of the national kidney foundation KDOQI guidelines: a survey of U.S. renal healthcare providers

Background

The National Kidney Foundation (NKF) Kidney Disease Outcomes Quality Initiative (KDOQI) developed guidelines to care for patients with chronic kidney disease (CKD). While these are disseminated through the NKF’s website and publications, the guidelines’ usage remains suboptimal. The KDOQI Educational Committee was formed to identify barriers to guideline implementation, determine provider and patient educational needs and develop tools to improve care of patients with CKD.

Methods

An online survey was conducted from May to September 2010 to evaluate renal providers’ familiarity, current use of and attitudes toward the guidelines and tools to implement the guidelines.

Results

Most responders reported using the guidelines often and felt that they could be easily implemented into clinical practice; however, approximately one-half identified at least one barrier. Physicians and physician extenders most commonly cited the lack of evidence supporting KDOQI guidelines while allied health professionals most commonly listed patient non-adherence, unrealistic guideline goals and provider time-constraints. Providers thought that the guidelines included too much detail and identified the lack of a quick resource as a barrier to clinical implementation. Most were unaware of the Clinical Action Plans.

Conclusions

Perceived barriers differed between renal clinicians and allied health professionals; educational and implementation tools tailored for different providers are needed.

Antiretroviral therapy-induced changes in plasma lipids and the risk of kidney dysfunction in HIV-infected men

In the context of HIV, the initiation of effective antiretroviral therapy (ART) has been found to increase the risk of dyslipidemia in HIV-infected individuals, and dyslipidemia has been found to be a risk factor for kidney disease in the general population. Therefore, we examined changes in lipid profiles in HIV-infected men following ART initiation and the association with future kidney dysfunction. HIV-infected men from the Multicenter AIDS Cohort Study initiating ART between December 31, 1995 and September 30, 2011 with measured lipid and serum creatinine values pre-ART and post-ART were selected. The associations between changes in total cholesterol or high-density lipoprotein following ART initiation and the estimated change in glomerular filtration rate (eGFR) over time were assessed using piecewise linear mixed effects models. There were 365 HIV-infected men who contributed to the analysis. In the adjusted models, at 3 years post-ART, those with changes in total cholesterol >50 mg/dl had an average decrease in eGFR of 2.6 ml/min/1.73 m(2) per year (p<0.001) and at 5 years post-ART, the average decrease was 2.4 ml/min/1.73 m(2) per year (p=0.008). This decline contrasted with the estimates for those with changes in total cholesterol ≤ 50 mg/dl: 1.4 ml/min/1.73 m(2) decrease per year (p<0.001) and 0.1 ml/min/1.73 m(2) decrease per year (p=0.594) for the same time periods, respectively. Large decreases in high-density lipoprotein (a decline of greater than 5 mg/dl) were not associated with declines in eGFR. These results indicate that large ART-related increases in total cholesterol may be a risk factor for kidney function decline in HIV-infected men. Should these results be generalizable to the broader HIV population, monitoring cholesterol changes following the initiation of ART may be important in identifying HIV-infected persons at risk for kidney disease.

Comparisons of creatinine and cystatin C for detection of kidney disease and prediction of all-cause mortality in HIV-infected women

BACKGROUND

Cystatin C could improve chronic kidney disease (CKD) classification in HIV-infected women relative to serum creatinine.

DESIGN

Retrospective cohort analysis.

METHODS

Cystatin C and creatinine were measured from specimens taken and stored during the 1999-2000 examination among 908 HIV-infected participants in the Women's Interagency HIV study (WIHS). Mean follow-up was 10.2 years. Predictors of differential glomerular filtration rate (GFR) estimates were evaluated with multivariable linear regression. The associations of baseline categories (<60, 60-90, and >90 ml/min per 1.73 m) of creatinine estimated GFR (eGFRcr), cystatin C eGFR (eGFRcys), and combined creatinine-cystatin C eGFR (eGFRcr-cys) with all-cause mortality were evaluated using multivariable Cox regression. The net reclassification index (NRI) was calculated to evaluate the effect of cystatin C on reclassification of CKD staging.

RESULTS

CKD risk factors were associated with lower eGFRcys and eGFRcr-cys values compared with eGFRcr. Relative to eGFR more than 90, the eGFR less than 60 category by eGFRcys (Adjusted hazard ratio: 2.56; 95% confidence interval: 1.63-4.02), eGFRcr-cys (3.11; 1.94-5.00), and eGFRcr (2.34; 1.44-3.79) was associated with increased mortality risk. However, the eGFR 60-90 category was associated with increased mortality risk for eGFRcys (1.80; 1.28-2.53) and eGFRcr-cys (1.91; 1.38-2.66) but not eGFRcr (1.20; 0.85-1.67). The overall NRI for mortality was 26% when reclassifying from eGFRcr to eGFRcys (P < 0.001) and was 20% when reclassifying from eGFRcr to eGFRcr-cys (P < 0.001).

CONCLUSION

The addition of cystatin C may improve mortality risk prediction by stages of kidney function relative to creatinine. CKD risk factors are associated with an overestimate of GFR by serum creatinine relative to cystatin C.

Does HIV infection promote early kidney injury in women?

BACKGROUND

In HIV-infected women, urine concentrations of novel tubulointerstitial injury markers, interleukin-18 (IL-18) and kidney injury marker-1 (KIM-1), are associated with kidney function decline and all-cause mortality. We hypothesized that HIV-infected individuals with preserved kidney filtration function would have more extensive kidney injury, as determined by urine injury markers, compared to the uninfected controls, and that risk factors for tubulointerstitial injury would differ from risk factors for albuminuria.

METHODS

In this cross-sectional study, we compared urine concentrations of IL-18, KIM-1 and albumin-to-creatinine ratio (ACR) in 908 HIV-infected and 289 HIV-uninfected women enrolled in the Women's Interagency HIV Study, utilizing stored urine specimens from visits between 1999 and 2000.

RESULTS

After multivariate-adjusted linear regression analysis, mean urine concentrations were higher in HIV-infected individuals by 38% for IL-18 (P<0.0001), 12% for KIM-1 (P=0.081) and 47% for ACR (P<0.0001). Higher HIV RNA level (15% per 10-fold increase; P<0.0001), lower CD4(+) lymphocyte count (8% per doubling; P=0.0025), HCV infection (30%; P=0.00018) and lower high-density lipoprotein (5% per 10 mg/dl; P=0.0024) were each associated with higher IL-18 concentrations. In contrast, hypertension (81%; P<0.0001) and diabetes (47%; P=0.018) were among the strongest predictors of higher ACR, though HIV RNA level (15% per 10-fold increase; P=0.0004) was also associated with higher ACR.

CONCLUSIONS

HIV-infected women had more extensive tubulointerstitial and glomerular injury than uninfected women, but the associated factors differed among the urine biomarkers. Combinations of urinary biomarkers should be investigated to further characterize early kidney injury in HIV-infected women.

Hepatitis C viremia and the risk of chronic kidney disease in HIV-infected individuals

BACKGROUND

 The role of active hepatitis C virus (HCV) replication in chronic kidney disease (CKD) risk has not been clarified.

METHODS

 We compared CKD incidence in a large cohort of HIV-infected subjects who were HCV seronegative, HCV viremic (detectable HCV RNA), or HCV aviremic (HCV seropositive, undetectable HCV RNA). Stages 3 and 5 CKD were defined according to standard criteria. Progressive CKD was defined as a sustained 25% glomerular filtration rate (GFR) decrease from baseline to a GFR < 60 mL/min/1.73 m2. We used Cox models to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

 A total of 52 602 HCV seronegative, 9508 HCV viremic, and 913 HCV aviremic subjects were included. Compared with HCV seronegative subjects, HCV viremic subjects were at increased risk for stage 3 CKD (adjusted HR 1.36 [95% CI, 1.26, 1.46]), stage 5 CKD (1.95 [1.64, 2.31]), and progressive CKD (1.31 [1.19, 1.44]), while HCV aviremic subjects were also at increased risk for stage 3 CKD (1.19 [0.98, 1.45]), stage 5 CKD (1.69 [1.07, 2.65]), and progressive CKD (1.31 [1.02, 1.68]).

CONCLUSIONS

 Compared with HIV-infected subjects who were HCV seronegative, both HCV viremic and HCV aviremic individuals were at increased risk for moderate and advanced CKD.

Online CKD education for medical students, residents, and fellows: training in a new era

CKD and its complications are associated with substantial morbidity and mortality. Studies have highlighted significant deficiencies in resident knowledge and awareness of CKD and its complications. There is a need to improve CKD education through medical school and residency. There is also a need to provide alternatives to traditional teaching methods to meet the challenges of learning in the context of work-hour restrictions and increasing workload among residents and fellows. Internet-based learning resources offer various educational tools, including websites, kidney blogs, online modules, and smartphone applications, which could potentially and efficiently advance CKD knowledge among medical trainees. In this review, we describe several online resources for CKD education that could be useful for medical students, residents, and fellows. Increased awareness of these tools and their utilization may significantly influence and hopefully improve the recognition and management of patients with CKD. Future studies may help evaluate the effectiveness of these online learning methods and their effect on CKD patient outcomes. In addition, in light of increased concern about nephrology workforce issues, the potential for these online tools to augment interest in nephrology careers should be investigated.

Host APOL1 genotype is independently associated with proteinuria in HIV infection

Proteinuria is associated with adverse clinical outcomes in HIV infection. Here we evaluated whether APOL1 risk alleles, previously associated with advanced kidney disease, are independently associated with proteinuria in HIV infection in a cross-sectional study of HIV-infected women in the Women's Interagency HIV Study. We estimated the percent difference in urine protein excretion and odds of proteinuria (≥200 mg/g) associated with two versus one or no APOL1 risk allele using linear and logistic regression, respectively. Of 1285 women successfully genotyped, 379 carried one and 80 carried two risk alleles. Proteinuria was present in 124 women, 78 of whom had proteinuria confirmed on a second sample. In women without prior AIDS, two risk alleles were independently associated with a 69% higher urine protein excretion (95% confidence interval (CI): 36, 108) and five-fold higher odds of proteinuria (95% CI: 2.45, 10.37) as compared with one or no risk allele. No association was found in women with prior AIDS. Analyses in which women with impaired kidney function were excluded and proteinuria was confirmed by a second urine sample yielded similar estimates. Thus, APOL1 risk alleles are associated with significant proteinuria in HIV-infected persons without prior clinical AIDS, independent of clinical factors traditionally associated with proteinuria. Trials are needed to determine whether APOL1 genotyping identifies individuals who could benefit from earlier intervention to prevent overt renal disease.

Comparison of risk factors and outcomes in HIV immune complex kidney disease and HIV-associated nephropathy

BACKGROUND AND OBJECTIVES

HIV-associated nephropathy (HIVAN) is well described, but the clinical features of a group of renal pathologies characterized by Ig or immune complex depositions referred to as HIV-associated immune complex kidney disease (HIVICK) have not been well established. The objective of this study is to assess risk factors for HIVICK compared with contemporaneous control participants.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A nested case-control study of 751 HIV-infected patients followed from January 1996 to June 2010 was conducted. Groups were compared using the chi-squared test or rank-sum analysis. Conditional logistic regression was used to estimate odds ratios (ORs) for HIVICK. Incidences of overall ESRD and with/without combined antiretroviral therapy (cART) exposure were calculated.

RESULTS

HIVICK patients were predominantly African American (92%). Compared with matched controls, patients with HIVICK were more likely to have HIV RNA >400 copies/ml (OR, 2.5; 95% confidence interval [95% CI], 1.2 to 5.2), diabetes (OR, 2.8; 95% CI, 1.1 to 6.8), and hypertension (OR, 2.3; 95% CI, 1.2 to 4.5). Compared with HIVAN, patients with HIVICK had more antiretroviral therapy exposure, lower HIV viral loads, and higher CD4 and estimated GFR. ESRD was less common in the HIVICK versus the HIVAN group (30% versus 82%; P<0.001), and the use of cART was not associated with ESRD in HIVICK patients (25% versus 26; P=0.39).

CONCLUSIONS

HIVICK was predominantly observed in African-American patients and associated with advanced HIV disease. ESRD incidence is lower in HIVICK patients compared with those with HIVAN. Unlike HIVAN, cART use was not associated with the incidence of ESRD in HIVICK.

Antiretroviral-treated HIV-infected women have similar long-term kidney function trajectories as HIV-uninfected women

Natural history studies suggest increased risk for kidney function decline with HIV infection, but few studies have made comparisons with HIV-uninfected women. We examined whether HIV infection treated with highly active antiretroviral therapy (HAART) remains associated with faster kidney function decline in the Women's Interagency HIV Study. HIV-infected women initiating HAART with (n=105) or without (n=373) tenofovir (TDF) were matched to HIV-uninfected women on calendar and length of follow-up, age, systolic blood pressure, hepatitis C antibody serostatus, and diabetes history. Linear mixed models were used to evaluate differences in annual estimated glomerular filtration rate (eGFR). Person-visits were 4,741 and 11,512 for the TDF-treated and non-TDF-treated analyses, respectively. Mean baseline eGFRs were higher among women initiated on TDF-containing HAART and lower among those on TDF-sparing HAART compared to their respective HIV-uninfected matches (p<0.05 for both). HIV-infected women had annual rates of eGFR changes similar to HIV-uninfected matches (p-interaction >0.05 for both). Adjusting for baseline eGFR, mean eGFRs at 1 and 3 years of follow-up among women initiated on TDF-containing HAART were lower than their uninfected matches (-4.98 and -4.26 ml/min/1.73 m(2), respectively; p<0.05 for both). Mean eGFR of women initiated on TDF-sparing HAART was lower versus uninfected matches at 5 years (-2.19 ml/min/1.73 m(2), p=0.03). HAART-treated HIV-infected women had lower mean eGFRs at follow-up but experienced rates of annual eGFR decline similar to HIV-uninfected women. Tenofovir use in HIV-infected women with normal kidney function did not accelerate long-term kidney function decline relative to HIV-uninfected women.

The impact of impaired kidney function and HIV infection on the risk of anemia

Chronic kidney disease and HIV infection both independently increase the risk of anemia. It is not known if individuals with both HIV infection and kidney dysfunction are at greater than expected risk of anemia resulting from the combined effect of these factors. Men from the Multicenter AIDS Cohort Study with AIDS-free time after 1996 were included in the analysis if they had an initial hemoglobin value greater than 13 g/dl and available serum creatinine measurements for the estimation of glomerular filtration rate. Hemoglobin data were fit parametrically using a linear mixed effects model and effects of medication use on hemoglobin levels were removed using censoring methods. The effect of both HIV infection and glomerular filtration rate less than 60 ml/min/1.73 m(2) on the mean hemoglobin value was assessed. The risk of having anemia (hemoglobin level falling below 13 g/dl) was estimated. There were 862 HIV-infected and 1,214 HIV-uninfected men who contributed to the analysis. Hemoglobin values across all 17,341 person-visits, adjusting for age, were generally lower in HIV-infected AIDS-free men with impaired kidney function by -0.22 g/dl (95% CI: -0.42, -0.03) compared to men with either HIV infection or impaired kidney function, but not both. HIV-infected AIDS-free men with impaired kidney function have a higher risk of anemia by 1.2% compared to HIV-uninfected men with normal kidney function. Comorbid conditions and medication use did not explain this increase in risk. HIV infection and impaired kidney function have a combined impact on lowering hemoglobin levels, resulting in a higher risk of anemia.

Efficacy of an internet-based tool for improving physician knowledge of chronic kidney disease: an observational study

Background

Early recognition and management of chronic kidney disease (CKD) are associated with better outcomes. Internal medicine residency should prepare physicians to diagnose and manage CKD.

Methods

To examine whether residency training and program characteristics were associated with CKD knowledge and investigate the effectiveness of an internet-based training module in improving CKD knowledge, we analyzed data from CKD training modules administered annually to U.S. internal medicine residents from July 1, 2005 to June 30, 2009. Baseline CKD knowledge was assessed using pre-tests. The modules’ effectiveness was evaluated by post-tests. Comparisons were performed using X² tests and paired t-tests.

Results

Of 4,702 residents, 38%, 33%, and 29% were program year (PGY)-1, PGY-2, and PGY-3, respectively. Baseline CKD knowledge was poor, with mean pre-test scores of 45.1-57.0% across the four years. The lowest pre-test performance was on CKD recognition. Pre-test scores were better with higher training levels (P-trend < 0.001 except 2005–2006 [P-trend = 0.35]). Affiliation with a renal fellowship program or program location within a region of high end-stage kidney disease prevalence was not associated with better baseline CKD knowledge. Completion of the CKD module led to significant improvements from pre- to post-test scores (mean improvement 27.8% [SD: 21.3%] which were consistent from 2005 to 2009.

Conclusions

Knowledge of diagnosis and management of CKD improves during residency training but remains poor among graduating residents. Web-based training can be effective in educating physicians on CKD-related issues. Studies are needed to determine whether knowledge gained from such an intervention translates to improved care of CKD patients.

Predictors of kidney biopsy complication among patients with systemic lupus erythematosus

Kidney biopsy is essential for the diagnosis and management of lupus nephritis. The risk of bleeding complication, however, is not defined in the systemic lupus erythematosus population. A retrospective cohort study was conducted to determine predictors of major and minor complications among patients with systemic lupus erythematosus undergoing percutaneous ultrasound-guided kidney biopsy. Major complications included bleeding necessitating intervention, hypotension requiring vasopressors or higher level of care or death. Minor complications included moderate or large (≥ 4 cm in largest diameter) perinephric hematoma, gross hematuria or voiding difficulties. All patients were observed for at least 23 h post-procedure. The overall incidence of bleeding was 10.5% (2.7% major, 7.8% minor). Adjusted logistic regression showed that for every 10,000 cells/mm(3) decrease in platelet count, risk for major and any complication increased by 27% (odds ratio 1.27; 95% confidence intervals 1.06-1.51; p = 0.01) and 8% (odds ratio 1.08; 95% confidence intervals 1.02-1.15; p = 0.01), respectively. Patients with a platelet count <150,000 cells/mm(3) were 30 times more likely to experience a major complication (p = 0.002). Other candidate predictors, including steroid exposure, kidney function, hematocrit and histopathology, were not significant. Kidney biopsies are well tolerated in patients with systemic lupus erythematosus. However, patients with pre-biopsy platelet counts <150,000 cells/mm(3) are at markedly increased risk for a major bleeding complication.

APOL1 risk variants predict histopathology and progression to ESRD in HIV-related kidney disease

With earlier institution of antiretroviral therapy, kidney diseases other than HIV-associated nephropathy (HIVAN) predominate in HIV-infected persons. Outcomes for these diseases are typically worse among those infected with HIV, but the reasons for this are not clear. Here, we examined the role of APOL1 risk variants in predicting renal histopathology and progression to ESRD in 98 HIV-infected African Americans with non-HIVAN kidney disease on biopsy. We used survival analysis to determine time to ESRD associated with APOL1 genotype. Among the 29 patients with two APOL1 risk alleles, the majority (76%) had FSGS and 10% had hypertensive nephrosclerosis. In contrast, among the 54 patients with one APOL1 risk allele, 47% had immune-complex GN as the predominant lesion and only 23% had FSGS. Among the 25 patients with no APOL1 risk allele, 40% had immune-complex GN and 12% had FSGS. In 310 person-years of observation, 29 patients progressed to ESRD. In adjusted analyses, individuals with two APOL1 risk alleles had a nearly three-fold higher risk for ESRD compared with those with one or zero risk alleles (P=0.03). In summary, these data demonstrate an association between APOL1 variants and renal outcomes in non-HIVAN kidney disease, suggesting a possible use for APOL1 genotyping to help guide the care of HIV-infected patients.

Kidney function and mortality post-liver transplant in the Model for End-Stage Liver Disease era

The Model for End-Stage Liver Disease (MELD) score incorporates serum creatinine and was introduced to facilitate allocation of orthotopic liver transplantation (LT). The objective is to determine the impact of MELD and kidney function on all-cause mortality. Among LTs performed in a tertiary referral hospital between 1995 and 2009, 419 cases were studied. Cox proportional hazards models were constructed to estimate the hazard ratios (HR) and 95% confidence intervals (CI) for death. Over mean follow-ups of 8.4 and 3.1 years during the pre-MELD and MELD era, 57 and 63 deaths were observed, respectively. Those transplanted during the MELD era had a higher likelihood of hepatorenal syndrome (8% vs 2%, P < 0.01), lower kidney function (median estimated glomerular filtration rate [eGFR] 77.8 vs 92.6 mL/ min/1.73 m², P < 0.01), and more pretransplantation renal replacement therapy (RRT) (5% vs 1%; P < 0.01). All-cause mortality risk was similar in the MELD vs the pre-MELD era (HR: 0.98, 95% CI: 0.58–1.65). The risk of death, however, was nearly 3-fold greater (95% CI: 1.14–6.60) among those requiring pre- transplant RRT. Similarly, eGFR < 60 mL/min/1.73 m² post-transplant was associated with a 2.5-fold higher mortality (95% CI: 1.48–4.11). The study suggests that MELD implementation had no impact on all-cause mortality post-LT. However, the need for pre-transplant RRT and post-transplant kidney dysfunction was associated with a more than 2-fold greater risk of subsequent death.

The impact of hepatitis C coinfection on kidney disease related to human immunodeficiency virus (HIV): a biopsy study

Approximately 1 in 4 individuals infected with the human immunodeficiency virus (HIV) in the United States is coinfected with the hepatitis C virus. Both conditions increase the risk for the development and progression of kidney disease. The effect, however, of coexisting HIV and hepatitis C infection on the spectrum and progression of kidney disease is not well known. To compare the clinical features, histopathologic kidney diagnoses, and proportion of individuals progressing to end-stage kidney disease (ESKD), we reviewed the clinical records of HIV-infected individuals with and without hepatitis C coinfection who underwent ultrasound-guided percutaneous kidney biopsies between February 7, 1995, and March 30, 2009.Of the 249 HIV-infected individuals included in this study, 58% were coinfected with hepatitis C. Coinfected individuals were older (mean age, 46 ± 7 vs. 44 ± 10 yr, respectively; p < 0.01) and more likely to have used illicit drugs (85% vs. 14%, respectively; p < 0.01) compared to HIV-infected individuals without hepatitis C. HIV-associated nephropathy was the most common histopathologic diagnosis in both groups. Immune-complex glomerulonephritides (ICGNs), including lupus-like nephritis, postinfectious glomerulonephritis, membranous glomerulopathy, membranoproliferative glomerulonephritis, IgA nephropathy, and nonspecific ICGNs, occurred more frequently in individuals coinfected with hepatitis C than in those not coinfected (22% vs. 11%, respectively; p = 0.02). Although the proportion of those who died was similar between the 2 groups, hepatitis C coinfection was independently associated with a greater risk of progression to ESKD (hazard ratio, 1.81; 95% confidence interval, 1.09-2.99; p = 0.02).The current study demonstrates that coinfection with hepatitis C in individuals infected with HIV predisposes these individuals to immune-complex glomerulonephritides and is associated with increased risk of ESKD in the biopsied population.

Fluid balance, diuretic use, and mortality in acute kidney injury

BACKGROUND AND OBJECTIVES

Management of volume status in patients with acute kidney injury (AKI) is complex, and the role of diuretics is controversial. The primary objective was to elucidate the association between fluid balance, diuretic use, and short-term mortality after AKI in critically ill patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using data from the Fluid and Catheter Treatment Trial (FACTT), a multicenter, randomized controlled trial evaluating a conservative versus liberal fluid-management strategy in 1000 patients with acute lung injury (ALI), we evaluated the association of post-renal injury fluid balance and diuretic use with 60-day mortality in patients who developed AKI, as defined by the AKI Network criteria.

RESULTS

306 patients developed AKI in the first 2 study days and were included in our analysis. There were 137 in the fluid-liberal arm and 169 in the fluid-conservative arm (P=0.04). Baseline characteristics were similar between groups. Post-AKI fluid balance was significantly associated with mortality in both crude and adjusted analysis. Higher post-AKI furosemide doses had a protective effect on mortality but no significant effect after adjustment for post-AKI fluid balance. There was no threshold dose of furosemide above which mortality increased.

CONCLUSIONS

A positive fluid balance after AKI was strongly associated with mortality. Post-AKI diuretic therapy was associated with 60-day patient survival in FACTT patients with ALI; this effect may be mediated by fluid balance.

Recent developments in HIV-related kidney disease

Although kidney disease has been a recognized complication of HIV infection since the beginning of the HIV epidemic, its epidemiology, underlying causes and treatment have evolved in developed countries where HAART has been widely available. HIV-associated nephropathy and HIV immune complex-mediated kidney disease were the prominent renal diagnoses in the earlier period of the HIV epidemic. While HIV immune complex-mediated kidney disease remains a common finding among HIV-infected individuals with kidney disease, the incidence of HIV-associated nephropathy has been diminishing in developed countries. The role of the metabolic effects of long-term HAART exposure and nephrotoxicity of certain antiretroviral medications on the development and progression of chronic kidney disease is now of increasing concern. The long-term clinical implications of acute kidney injury among HIV-infected persons are increasingly recognized. Kidney disease in HIV-infected persons continues to be a major risk factor for morbidity and mortality in this patient population; therefore, early recognition and treatment of kidney disease are imperative in lessening the impact of kidney disease on the health of HIV-infected individuals. This review focuses on recent developments and ongoing challenges in the understanding, diagnosis and management of HIV-related kidney disease.

Prevalence of kidney disease in anaemia differs by GFR-estimating method: the Third National Health and Nutrition Examination Survey (1988-94)

BACKGROUND

Anaemia worsens as kidney function declines. Both conditions are associated with increased mortality. Serum cystatin C is purportedly a more sensitive marker of kidney disease and a better predictor of mortality than serum creatinine. However, studies suggest that extrarenal factors also influence cystatin C levels.

METHODS

We determined whether estimates of glomerular filtration rate [estimated glomerular filtration rate (eGFR)] based on serum cystatin C alone or in combination with serum creatinine were superior to those based on serum creatinine in recognizing impaired kidney function in the setting of anaemia in a sub-sample of the Third National Health and Nutrition Examination Survey of the USA consisting of 6734 participants, 20 years or older.

RESULTS

The prevalence of moderate to severe kidney disease (eGFR 15-59 mL/min/1.73 m(2)) among anaemic persons was 15-16% when based on serum creatinine alone (eGFR(SCR)) or combined with cystatin C (eGFR(SCR) (+) (CYSC)); this estimate increased to nearly 25% when kidney function was estimated by cystatin C (eGFR(CYSC)). The adjusted odds ratios of kidney disease in anaemic versus non-anaemic persons were slightly higher with eGFR(CYSC) than eGFR(SCR) and eGFR(SCR) (+) (CYSC) in younger adults [odds ratio (OR) = 5.22, 95% confidence interval (CI): 2.23, 12.17], women (OR = 5.34, 95% CI: 2.36, 12.06) and those with elevated C-reactive protein (CRP) (OR = 7.36, 95% CI: 1.98-27.36).

CONCLUSIONS

Impaired kidney function was common in individuals with anaemia. Among anaemic individuals, the prevalence estimate for kidney disease was notably higher when kidney function was estimated by cystatin C alone compared with the estimations by serum creatinine alone or in combination with serum cystatin C. eGFR(CYSC) may be particularly helpful in identifying kidney disease in the setting of anaemia among younger persons, women and those with elevated CRP. Regardless of which renal biomarker is used, our study suggests that an evaluation for underlying kidney disease should be considered in the standard workup of anaemia.

Screening for chronic kidney disease in HIV-infected patients

With improved survival afforded by highly active antiretroviral therapy (HAART), CKD has emerged as one of the primary comorbid conditions affecting HIV-infected individuals. Although CKD in HIV-infected individuals is classically thought of as a consequence of advanced HIV infection such as in the case of HIV-associated nephropathy, several factors likely contribute to the development CKD in HIV infection. These factors include genetic predisposition, age-related decline in kidney function, HAART-related metabolic changes, exposure to multiple nephrotoxic medications, and concurrent conditions such as hepatitis C or illicit drug use. Similar to the general population, proteinuria and impaired kidney function are associated with faster progression to acquired immune deficiency syndrome and death. Given the prevalence and impact of kidney disease on the course of HIV infection and its management, current guidelines recommend screening all HIV-infected individuals for kidney disease. This review focuses on the current guidelines for kidney disease screening and discusses traditional as well as promising strategies for detecting CKD in this vulnerable population.