Anemia treatment with Q2W darbepoetin alfa in patients with chronic kidney disease naïve to erythropoiesis-stimulating agents

OBJECTIVE

To evaluate the efficacy and safety of darbepoetin alfa dosed every-other-week (Q2W) to treat anemia in subjects with chronic kidney disease (CKD), not receiving dialysis, who were naïve to erythropoiesis-stimulating agent (ESA) therapy.

RESEARCH DESIGN AND METHODS

This was an open-label, multicenter, single-arm study enrolling ESA-naïve CKD subjects with baseline hemoglobin (Hb) < 11.0 g/dL. Q2W darbepoetin alfa treatment was initiated at a dose of 0.75 microg/kg and titrated to achieve and maintain Hb levels at 11.0-13.0 g/dL. Treatment was administered from week 1 to week 19.

MAIN OUTCOME MEASURES

The primary endpoint was the proportion of subjects who achieved Hb > or = 11 g/dL at any study visit, except in week 1. Hb levels, darbepoetin alfa dose, and safety were also assessed.

RESULTS

Of the 128 subjects who received at least one dose of darbepoetin alfa and of the subjects who completed the study, 118 (92%) and 112 (97%), respectively, achieved a Hb > or = 11 g/dL in a median time of 5 weeks. Median darbepoetin alfa dose at week 1 and at the time of achieving a Hb > or = 11 g/dL were 60 and 80 microg, respectively. Darbepoetin alfa was well-tolerated, and short-term adverse events were consistent with those expected in CKD subjects.

CONCLUSIONS

This study demonstrates that de novo Q2W darbepoetin alfa was effective in correcting and maintaining Hb levels in ESA-naïve subjects with CKD who were not receiving dialysis. Study limitations, including lack of a control arm for the study and multiple race information for subjects, must be considered in interpreting the results.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT00112008.

An open-label study of darbepoetin alfa administered once monthly for the maintenance of haemoglobin concentrations in patients with chronic kidney disease not receiving dialysis

OBJECTIVE

To demonstrate the efficacy and safety of once-monthly (QM) darbepoetin alfa administration in maintaining haemoglobin (Hb) 11.0-13.0 g dL(-1) in subjects with chronic kidney disease (CKD) not receiving dialysis and previously treated with darbepoetin alfa every other week (Q2W).

SUBJECTS

This open-label study enrolled subjects > or =18 years of age who had glomerular filtration rate > or =15 and < or =60 mL min(-1)/1.73 m(2), had Hb 11.0-13.0 g dL(-1), and were receiving Q2W darbepoetin alfa.

DESIGN

Subjects were switched to QM darbepoetin alfa therapy for 28 weeks; the QM dose was titrated to maintain Hb levels. Primary end-point: proportion of subjects maintaining Hb > or =11.0 g dL(-1) during the final 8 weeks of the study (evaluation phase). Secondary end-points: Hb concentration during evaluation, darbepoetin alfa dose during the study, adverse events, laboratory parameters, and blood pressure.

RESULTS

The study enrolled 152 subjects (female 52%, white 64%). Mean Hb > or =11.0 g dL(-1) during evaluation was achieved by 76% of the 150 subjects who received at least one dose of darbepoetin alfa [95% confidence interval (CI): 68%, 83%]. Mean (SD) Hb during evaluation was 11.71 (0.92) g dL(-1). Eighty-five per cent of 129 subjects who completed the study (95% CI: 78%, 91%) had Hb > or =11.0 g dL(-1) during evaluation. The dose of darbepoetin alfa over the study period was median (95% CI) 124.4 mug (106.2, 140.0). Darbepoetin alpha administered QM was well tolerated in study subjects.

CONCLUSION

Darbepoetin alpha administered QM maintained Hb in study subjects with CKD not receiving dialysis.

Investigating hepatitis C virus heterogeneity in a high prevalence setting using heteroduplex tracking analysis

Hepatitis C virus (HCV) infection is very common among chronic hemodialysis patients. In the past, blood transfusion appeared to be the primary risk factor; however evidence of nosocomial HCV transmission in the hemodialysis setting has recently been reported. This report describes a molecular investigation of HCV isolates obtained from a population of 670 patients attending six different Seattle-King County based hemodialysis centers in order to identify potential common source infections. 733 serum specimens were collected from hemodialysis patients in 1992 and 1996, and were tested for HCV antibodies and RNA. Overall, 115 of 670 (17%) patients were positive for HCV RNA, and thus were considered actively infected by HCV. HCV genotype was determined in all cases by restriction fragment length polymorphism, and 93 patients were found to be infected by HCV genotype 1. HCV envelope genes were amplified from the 93 patients with genotype 1 infection, and were studied in further detail by heteroduplex tracking analysis (HTA) using genotype 1a and 1b specific probes derived from the envelope 1 (E1) and envelope 2 (E2) genes. Genetic relatedness between pairs of HCV envelope genes was estimated by calculating the degree of gel shift relative to homoduplex controls. Nucleotide sequencing and phylogenetic analysis was used to confirm genetic relatedness detected by HTA. When HTA was performed using the E1 gene probe, 12 apparently related infections were detected; 10 of 12 (83%) of these infections were confirmed as truly related using the gold standard method of nucleotide sequencing plus phylogenetic analysis. Using an E2 gene probe, 24 infections were apparently related, but only six (25%) were confirmed by sequencing. As a control, 41 envelope genes, which were unrelated by HTA, were sequenced; 0 of 41 (0%) were truly related. In summary, HTA provides a rapid and effective molecular technique for screening HCV genetic relatedness in population-based studies, and should prove valuable in future studies of HCV molecular epidemiology.

Gender and the progression of renal disease

Many studies of chronic renal disease have reported that men have a more rapid progression of renal insufficiency. However, other studies have found no differences between the sexes, and the true effect of sex on chronic renal disease remains a topic of controversy. There is evidence that women with non-diabetic renal diseases experience a slower progression, but in diabetic renal disease, the effect of gender is not yet established. Sex hormones may mediate the effects of gender on chronic renal disease, through alterations in the renin--angiotensin system, reduction in mesangial collagen synthesis, the modification of collagen degradation, and upregulation of nitric oxide synthesis.

Anthropometric measures and risk of death in children with end-stage renal disease

We evaluated the association between anthropometric measurements and death among pediatric patients with end-stage renal disease (ESRD) using data from the Pediatric Growth and Development Special Study (PGDSS) from the US Renal Data System. Height, growth velocity, and body mass index (BMI) were used for the analysis of 1,949 patients in the PGDSS. To standardize these measurements, SD scores (SDSs) were calculated using population data from the Third National Health and Nutrition Examination Survey. Using Cox proportional hazards models, we assessed the association between anthropometric measures and death, controlling for demographic factors and stratifying by age. Multivariate analysis showed that each decrease by 1 SDS in height was associated with a 14% increase in risk for death (adjusted relative risk [aRR], 1.14; 95% confidence interval [CI], 1.02 to 1.27; P = 0.017). For each 1 SDS decrease in growth velocity among patients in our sample, the risk for death increased by 12% (aRR, 1.12; 95% CI, 1.00 to 1.25; P = 0.043). There was a statistically significant U-shaped association between BMI and death (P = 0.001), with relatively low and high BMIs associated with an increased risk for death. In children with ESRD, growth delay and extremes in BMI are associated with an increased risk for mortality.

Increased risk of hip fracture among patients with end-stage renal disease

BACKGROUND

Although patients with end-stage renal disease (ESRD) are at increased risk for bone loss, the risk of hip fracture in this population is not known. We compared the risk of hip fracture among dialysis patients with the general population.

METHODS

We used data from the United States Renal Data System (USRDS) to identify all new Caucasian dialysis patients who began dialysis between January 1, 1989, and December 31, 1996. All hip fractures occurring during this time period were ascertained. The observed number of hip fractures was compared with the expected number based on the experience of residents of Olmstead County (MN, USA). Standardized incidence ratios were calculated as the ratio between observed and expected. The risk attributable to ESRD was calculated as the difference between the observed and expected rate of hip fracture per 1000 person-years.

RESULTS

The number of dialysis patients was 326,464 (55.9% male and 44.1% female). There were 6542 hip fractures observed during the follow-up period of 643, 831 patient years. The overall incidence of hip fracture was 7.45 per 1000 person years for males and 13.63 per 1000 person years for females. The overall relative risk for hip fracture was 4.44 (95% CI, 4.16 to 4.75) for male dialysis patients and 4.40 (95% CI, 4.17 to 4.64) for female dialysis patients compared with people of the same sex in the general population. While the age-specific relative risk of hip fracture was highest in the youngest age groups, the added risks of fracture associated with dialysis rose steadily with increasing age. The relative risk of hip fracture increased as time since first dialysis increased.

CONCLUSIONS

The overall risk of hip fracture among Caucasian patients with ESRD is considerably higher than in the general population, independent of age and gender.

Pre-eclampsia and premature labour among pregnant wowen with haematuria

The authors conducted a retrospective cohort study of pregnant women to estimate the prevalence and associated risk of adverse pregnancy outcomes among pregnant women with microhaematuria. Between 1 January 1993 and 15 March 1993 at University of Washington Medical Center, 328 consecutive births were identified, and demographic data, medical history, laboratory data and pregnancy outcomes were abstracted from hospital charts. The presence or absence of haematuria was determined in 276/328 cases. Sixteen per cent (44/276) of the women were found to have haematuria. Those with haematuria were at increased risk of developing pre-eclampsia (odds ratio [OR] = 9.5, 95% confidence interval [CI] 3.1, 28.2) and premature labour (OR = 3.8, 95% CI 1.5, 9.7). These associations persisted after controlling for age, race, and urinary tract infection (UTI) (pre-eclampsia OR=9.1, 95% CI 2.5, 33.7; premature labour OR = 4.2, 95% CI 1.2, 15.3). Infants of women with haematuria were at a non-significantly increased risk of low Apgar scores (OR = 2.8, 95% CI 0.7, 11.9) and low birthweight (OR=1.9, 95% CI 0.7, 4.7). In this observational study, microscopic haematuria was prevalent among pregnant women and was independently associated with an increased risk of adverse maternal complications.

Principles of dialysis: special issues in women

Nephrologists are frequently responsible for the primary care of their female patients. As such, they must be aware of medical issues that are unique to women. Although many of the medical considerations are similar to those in women without renal disease, there are a number of special considerations unique to end-stage renal disease (ESRD) patients. Women comprise a smaller proportion of the dialysis population and have better survival rates than men do. The improved survival is less marked than seen in the general population and may be function of differential susceptibility to disease processes, socio-cultural factors, or gender differences in acceptance or transplantation rates. A variety of factors are important in choosing dialysis modality including lifestyle issues and previous abdominal surgery. Women with ESRD are at high risk of both sexual and gonadal dysfunction, for which the latter may be treated with replacement hormones. Pregnancy is rare and requires an increase in the dose of dialysis and the care of a team of experienced physicians. Finally, awareness and implementation of routine health maintenance recommendations is essential in the care of female dialysis patients.

Focal segmental glomerular sclerosis among patients infected with hepatitis C virus

This study describes the occurence of hepatitis C virus (HCV) infection in the setting of focal segmental glomerular sclerosis (FSGS). All patients with the pathologic diagnosis of idiopathic FSGS between 1992 and 1996 at the University of Washington Hospitals were examined using a retrospective cohort study design. FSGS was determined by renal biopsy in the absence of secondary causes. Demographic, laboratory, and outcome data were collected in a standardized fashion. Six patients (50%) were infected with HCV. Patients with HCV infection and FSGS were primarily Black (67%), hypertensive (100%), had a history of intravenous drug abuse (83%), and had normal liver enzymes. Those with HCV infection and a history of IVDA appeared clinically and histologically similar to previously described cases of 'heroin nephropathy'. We demonstrate that there is a high prevalence of HCV infection in our population of patients with idiopathic FSGS. Although this may simply reflect an epiphenomenon, we propose that HCV infection may play a role in the development of FSGS in a predisposed host.

Unique changes in interstitial extracellular matrix composition are associated with rejection and cyclosporine toxicity in human renal allograft biopsies

Renal allograft loss from chronic rejection or cyclosporine toxicity (CsAT) is characterized by progressive interstitial fibrosis, yet the protein composition of these lesions is unknown. The normal tubular basement membrane (TBM) contains laminin (LM), collagen IV (containing collagen IV alpha chain 1 [COL4A1] and COL4A2), thrombospondin (TSP), and fibronectin (FN). Only TSP and FN extend beyond the TBM into the interstitial space. Very scanty amounts of interstitial collagens (I and III) are detected in the interstitium. In a pilot study of human renal allograft biopsy specimens, three patterns of extracellular matrix (ECM) composition were identified. Pattern 1 showed no change in ECM composition; pattern 2 showed generalized accumulation of collagens I and III in the interstitium; and pattern 3 showed new expression of COL4A3 and LM-beta2 in the proximal TBM. Criteria were established for the clinicopathological diagnosis of CsAT and rejection. These diagnoses were correlated with the ECM composition in 22 renal allograft biopsy specimens. Control groups were examined in a similar manner and included native kidney biopsy specimens from patients with other allografts (n = 7), renal biopsy specimens from patients with glomerular disease (n = 9), and renal allograft biopsy specimens from patients without clinicopathological evidence of renal disease. These data show that rejection is associated with pattern 3 and CsAT is associated with pattern 2. Thus, detection of ECM composition may be a useful adjunct to standard microscopy in distinguishing rejection from CsAT in renal allograft biopsy specimens. These data suggest that interstitial fibrosis associated with rejection and CsAT result from different pathogenic mechanisms.

Interferon-alpha treatment of posttransplant lymphoproliferative disorder in recipients of solid organ transplants

Posttransplant lymphoproliferative disorder (PTLD) has been treated with decreased immunosuppression, antiviral medications, anti-B lymphocyte agents, radiation therapy, and/or chemotherapy. However, a standardized stepwise approach to treatment has not been previously evaluated. In the present study, 19 consecutive patients presenting to a single institution with newly diagnosed PTLD were treated according to a sequential protocol that consisted of (1) a reduction in immunosuppressive medications plus, if feasible, resection or definitive radiation therapy of localized disease, (2) interferon-alpha, and (3) systemic chemotherapy. Of the 3 patients presenting exclusively with localized disease, two were treated with resection of pulmonary parenchymal nodules and one was treated with radiation therapy to a paraspinous mass, without evidence of recurrence at a mean follow-up of 31 months (range, 8 to 46 months). Sixteen patients presented with PTLD not amenable to local therapy, and they were treated daily with 3x10(6) units/m2 subcutaneous interferon-alpha. Total regression of PTLD (defined as disappearance of the tumor mass by physical examination or computed tomography scanning) was found in 8 of 14 patients who received at least 3 weeks of interferon therapy. Interferon-alpha therapy was continued for 6 to 9 months in the eight patients judged to be responders. None of these patients have relapsed to date with the same neoplastic clone. Two patients, however, developed new neoplastic clones. Seven patients received systemic chemotherapy with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) (n=1), EPOCH (etoposide, vincristine, and doxorubicin administered as a continuous infusion, with an intravenous bolus of cyclophosphamide and oral prednisone) (n=4), or EPOCH followed by DHAP (dexamethasone, cytarabine, and cisplatin) (n=2) after failure of interferon-alpha; five patients had a complete response. Only 1 of the 19 patients died of uncontrolled PTLD. These results suggest that the majority of solid organ transplant recipients who develop PTLD can be safely and successfully treated using a sequential approach to therapy.

Secondary hyperparathyroidism complicated by parathyromatosis

Secondary hyperparathyroidism is a common complication of chronic renal disease. Clinical signs and symptoms tend to be severe and often are not controlled with medical measures. When medical therapy fails, parathyroidectomy becomes necessary. Recurrent hyperparathyroidism is not uncommon following surgery. One cause of surgical failure is parathyromatosis, which has been described as multiple nodules of hyperfunctioning parathyroid tissue scattered throughout the lower neck, superior mediastinum, or the arm if autotransplantation has been performed. Five cases of parathyromatosis in patients with chronic renal failure were identified. Clinical characteristics, course, and prognosis of the patients are reported. All patients had evidence of renal osteodystrophy and complained of severe pruritus and bone and/or joint pain. Three of the five patients had evidence of soft tissue calcification, two complained of muscle weakness, two had multiple fractures, and two eventually died of complications resulting from parathyromatosis. In four of five cases, surgical and medical management were ineffective. The patients described illustrate the severe morbidity and mortality associated with the parathyromatosis in the setting of end-stage renal disease. The pathogenesis remains controversial. Although primary prevention appears to be the most effective means of avoiding this complication, it is mandatory that meticulous care be taken during surgical manipulation. If such measures fail, calcium supplementation, calcitriol, and phosphate restriction may be tried.

Hepatitis C virus associated membranous glomerulonephritis

Hepatitis C virus infection has been associated with a variety of extrahepatic disorders. We report four patients with membranous glomerulonephritis and hepatitis C virus infection. In contrast to patients previously reported with HCV infection and membranoproliferative glomerulonephritis, these patients have normal or minimally reduced complement levels and no evidence of rheumatoid factor or cryoglobulinemia. A liver biopsy in one patient was consistent with chronic active hepatitis although liver enzymes were only minimally elevated and coagulation studies normal. Three patients were treated with alpha-interferon with some success. Treatment with alpha-interferon may have a beneficial effect in reducing proteinuria and improving liver function and may be related to the ability of interferon to suppress viremia. Future studies need to focus on clarifying the role of the virus in causing glomerular disease and improving dosing strategies for alpha-interferon. Randomized, controlled studies need to be performed to determine whether the beneficial effect of alpha interferon is significant, and if so, if it is superior to conventional therapies.

Hepatitis C virus-associated glomerulonephritis

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease and is associated with a variety of extrahepatic manifestations, including cryoglobulinemia and glomerulonephritis. Epidemiologic evidence suggests that HCV infection may be a major risk factor for both cryoglobulinemic and type I membranoproliferative glomerulonephritis (MPGN). Clinical symptoms and laboratory data may or may not reflect the presence of chronic liver disease. Most patients have evidence of hypocomplementemia, circulating rheumatoid factors, and cryoglobulinemia. The pathogenesis of HCV-associated MPGN is probably a result of glomerular deposition of circulating HCV and anti-HCV antibodies. Treatment with interferon-alpha has been shown to improve proteinuria, suppress viremia, and stabilize renal function. However, patients often relapse after therapy is stopped. The optimal therapy remains to be defined but may involve different dosage regimens of interferon-alpha or the combination of several antiviral agents.