RENAL RESEARCH INSTITUTE SYMPOSIUM: The Longitudinal Chronic Kidney Disease Study: A Prospective Cohort Study of Predialysis Renal Failure

A pairwise likelihood augmented Cox estimator for left-truncated data

Survival data collected from a prevalent cohort are subject to left truncation and the analysis is challenging. Conditional approaches for left-truncated data could be inefficient as they ignore the information in the marginal likelihood of the truncation times. Length-biased sampling methods may improve the estimation efficiency but only when the underlying truncation time is uniform; otherwise, they may generate biased estimates. We propose a semiparametric method for left-truncated data under the Cox model with no parametric distributional assumption about the truncation times. Our approach is to make inference based on the conditional likelihood augmented with a pairwise likelihood, which eliminates the truncation distribution, yet retains the information about the regression coefficients and the baseline hazard function in the marginal likelihood. An iterative algorithm is provided to solve for the regression coefficients and the baseline hazard function simultaneously. By empirical process and U-process theories, it has been shown that the proposed estimator is consistent and asymptotically normal with a closed-form consistent variance estimator. Simulation studies show substantial efficiency gain of our estimator in both the regression coefficients and the cumulative baseline hazard function over the conditional approach estimator. When the uniform truncation assumption holds, our estimator enjoys smaller biases and efficiency comparable to that of the full maximum likelihood estimator. An application to the analysis of a chronic kidney disease cohort study illustrates the utility of the method.

Association of carotid intima-media thickness with cardiovascular risk factors and patient outcomes in advanced chronic kidney disease: the RRI-CKD study

Background: Chronic kidney disease (CKD) is associated with accelerated atherosclerosis and an increased risk of adverse cardiovascular disease (CVD) outcomes. The relationships of intima-media thickness (IMT), a measure of subclinical atherosclerosis, with traditional and nontraditional risk factors and with adverse outcomes in CKD patients are not well-established. Methods: IMT, clinical characteristics, cardiovascular risk factors, and clinical outcomes were measured in 198 subjects from the Renal Research Institute (RRI) CKD study, a four-center prospective cohort of patients with estimated glomerular filtration rate (eGFR) ≤ 50 mL/min/1.73 m² not requiring renal replacement therapy. Results: The patients averaged 61 ± 14 years of age; the mean eGFR was 29 ± 12 mL/min/1.73 m². Maximum IMT was more closely associated with traditional cardiovascular risk factors, including age, diabetes, dyslipidemia, and systolic blood pressure, than with nontraditional risk factors or with eGFR. Higher values of maximum IMT were also independently associated with clinical CVD and with other markers of subclinical CVD. Maximum IMT ≥ 2.6 mm was predictive of the composite endpoint of CVD events and death (hazard ratio (HR): 5.47 (95% confidence interval (CI): 2.97 – 10.07, p < 0.0001)) but was not related to progression to end-stage renal disease (HR: 1.67 (95% CI: 0.74 – 3.76, p = 0.21)). Conclusion: In patients with advanced pre-dialysis CKD, higher maximum IMT was associated with traditional cardiovascular risk factors, CVD, and other markers of subclinical CVD and was an independent predictor of cardiovascular events and death. Additional research is needed to examine the clinical utility of IMT in the risk stratification and clinical management of patients with CKD.

The Role of Personality and Social Support in Health-Related Quality of Life in Chronic Kidney Disease Patients

Background

Chronic kidney disease (CKD) is commonly associated with various negative health outcomes. The aim of this study was to examine the influence of personality and social support on health-related quality of life in patients with chronic kidney disease. Health-related quality of life (HRQoL) is the quality of life studied in relation to health, and it provides important information of patients’ coping with their health issues.

Method

Participants comprised of 200 patients experiencing various stages of chronic kidney disease. All participants completed the Short-Form 36 (SF-36), Big Five Inventory (BFI) and the Medical Outcomes Study (MOS) Social Support questionnaires.

Results

Participants consisted of 108 males (54.0%) and 92 females (46.0%) with the mean age of 59.3 years (SD 14.5). Results showed that higher levels of extraversion and lower perceived affectionate social support were associated with higher physical HRQoL, whereas higher levels of neuroticism were associated with poorer mental HRQoL.

Conclusion

The current study found that certain personality traits, namely extraversion and neuroticism, were found to be associated with HRQoL. In addition, affectionate social support was also associated with higher HRQoL. Therefore, special attention should be paid to the personality of CKD patients, as well as the type of social support that they have, in planning interventions to improve their health outcomes.

Serum sodium levels and patient outcomes in an ambulatory clinic-based chronic kidney disease cohort

BACKGROUND

Chronic kidney disease (CKD) patients are prone to both hypo- and hypernatremia. Little has been published on the epidemiology of hypo- and hypernatremia in ambulatory patients with non-dialysis CKD.

METHODS

Data collected in two contemporaneous CKD cohort studies, the Renal Research Institute (RRI)-CKD study (n = 834) and the Study of Treatment of Renal Insufficiency: Data and Evaluation (STRIDE) (n = 1,348) were combined and analyzed to study the association between serum sodium (Na(+)) and clinical outcomes.

RESULTS

Baseline estimated glomerular filtration rate (eGFR) and Na(+) were 26 ± 11 ml/min/1.73 m(2) and 140.2 ± 3.4 mEq/l, respectively. The prevalence of Na(+) ≤135 mEq/l and ≥144 mEq/l was 6 and 16%, respectively. Higher baseline Na(+) was significantly associated with male sex, older age, systolic blood pressure, BMI, serum albumin, presence of heart failure, and lower eGFR. The risk of end-stage renal disease (ESRD) was marginally significantly higher among patients with Na(+) ≤135 mEq/l, compared with 140< Na(+) <144 mEq/l (referent), in time-dependent models (adjusted hazard ratio, HR = 1.52, p = 0.06). Mortality risk was significantly greater at 135< Na(+) ≤140 mEq/l (adjusted HR = 1.68, p = 0.02) and Na(+) ≥144 mEq/l (adjusted HR = 2.01, p = 0.01).

CONCLUSION

CKD patients with Na(+) ≤135 mEq/l were at a higher risk for progression to ESRD, whereas both lower and higher Na(+) levels were associated with a higher risk of mortality. While caring for CKD patients, greater attention to serum sodium levels by clinicians is warranted and could potentially help improve patient outcomes.

The natural history of, and risk factors for, progressive chronic kidney disease (CKD): the Renal Impairment in Secondary care (RIISC) study; rationale and protocol

BACKGROUND

Chronic kidney disease (CKD) affects up to 16% of the adult population and is associated with significant morbidity and mortality. People at highest risk from progressive CKD are defined by a sustained decline in estimated glomerular filtration rate (eGFR) and/or the presence of significant albuminuria/proteinuria and/or more advanced CKD. Accurate mapping of the bio-clinical determinants of this group will enable improved risk stratification and direct the development of better targeted management for people with CKD.

METHODS/DESIGN

The Renal Impairment In Secondary Care study is a prospective, observational cohort study, patients with CKD 4 and 5 or CKD 3 and either accelerated progression and/or proteinuria who are managed in secondary care are eligible to participate. Participants undergo a detailed bio-clinical assessment that includes measures of vascular health, periodontal health, quality of life and socio-economic status, clinical assessment and collection of samples for biomarker analysis. The assessments take place at baseline, and at six, 18, 36, 60 and 120 months; the outcomes of interest include cardiovascular events, progression to end stage kidney disease and death.

DISCUSSION

The determinants of progression of chronic kidney disease are not fully understood though there are a number of proposed risk factors for progression (both traditional and novel). This study will provide a detailed bio-clinical phenotype of patients with high-risk chronic kidney disease (high risk of both progression and cardiovascular events) and will repeatedly assess them over a prolonged follow up period. Recruitment commenced in Autumn 2010 and will provide many outputs that will add to the evidence base for progressive chronic kidney disease.

Predictors of heart rate variability and its prognostic significance in chronic kidney disease

BACKGROUND

Heart rate variability (HRV), a noninvasive measure of autonomic dysfunction and a risk factor for cardiovascular disease (CVD), has not been systematically studied in nondialysis chronic kidney disease (CKD).

METHODS

HRV was assessed using 24-h Holter monitoring in 305 subjects from the Renal Research Institute-CKD Study, a four-center prospective cohort of CKD (Stages 3-5). Multiple linear regression was used to assess predictors of HRV (both time and frequency domain) and Cox regression used to predict outcomes of CVD, composite of CVD/death and end-stage renal disease (ESRD).

RESULTS

A total of 47 CVD, 67 ESRD and 24 death events occurred over a median follow-up of 2.7 years. Lower HRV was significantly associated with older age, female gender, diabetes, higher heart rate, C-reactive protein and phosphorus, lower serum albumin and Stage 5 CKD. Lower HRV (mostly frequency domain) was significantly associated with higher risk of CVD and the composite end point of CVD or death. Significantly, lower HRV (frequency domain) was associated with higher risk of progression to ESRD, although this effect was relatively weaker.

CONCLUSIONS

This study draws attention to the importance of HRV as a relatively under recognized predictor of adverse cardiovascular and renal outcomes in patients with nondialysis CKD. Whether interventions that improve HRV will improve these outcomes in this high-risk population deserves further study.

Serum potassium and outcomes in CKD: insights from the RRI-CKD cohort study

BACKGROUND AND OBJECTIVES

The relationship between serum potassium (S(K)) and mortality in chronic kidney disease (CKD) has not been systematically investigated.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We examined the predictors and mortality association of S(K) in the Renal Research Institute CKD Study cohort, wherein 820 patients with CKD were prospectively followed at four US centers for an average of 2.6 years. Predictors of S(K) were investigated using linear and repeated measures regression models. Associations between S(K) and mortality, the outcomes of ESRD, and cardiovascular events in time-dependent Cox models were examined.

RESULTS

The mean age was 60.5 years, 80% were white, 90% had hypertension, 36% had diabetes, the average estimated GFR was 25.4 ml/min per 1.73 m(2), and mean baseline S(K) was 4.6 mmol/L. Higher S(K) was associated with male gender, lower estimated GFR and serum bicarbonate, absence of diuretic and calcium channel blocker use, diabetes, and use of angiotensin-converting enzyme inhibitors and/or statins. A U-shaped relationship between S(K) and mortality was observed, with mortality risk significantly greater at S(K) < or = 4.0 mmol/L compared with 4.0 to 5.5 mmol/L. Risk for ESRD was elevated at S(K) < or = 4 mmol/L in S(K) categorical models. Only the composite of cardiovascular events or death as an outcome was associated with higher S(K) (> or = 5.5).

CONCLUSIONS

Although clinical practice usually emphasizes greater attention to elevated S(K) in the setting of CKD, our results suggest that patients who have CKD and low or even low-normal S(K) are at higher risk for dying than those with mild to moderate hyperkalemia.

Establishing a national chronic kidney disease surveillance system for the United States

Despite the recognized importance of chronic kidney disease (CKD), the United States currently lacks a comprehensive, systematic surveillance program that captures and tracks all aspects of CKD in the population. As part of its CKD Initiative, the Centers for Disease Control and Prevention (CDC) funded two teams to jointly initiate the development of a CKD surveillance system. Here, we describe the process and methods used to establish this national CDC CKD Surveillance System. The major CKD components covered include burden (incidence and prevalence), risk factors, awareness, health consequences, processes and quality of care, and health system capacity issues. Goals include regular reporting of the data collected, plus development of a dynamic project web site and periodic issuance of a CKD fact sheet. We anticipate that this system will provide an important foundation for widespread efforts toward primary prevention, earlier detection, and implementation of optimal disease management strategies, with resultant increased awareness of CKD, decreased rates of CKD progression, lowered mortality, and reduced resource utilization. Final success will be measured by usage, impact, and endorsement.

Applicability of estimated glomerular filtration rate in stratifying chronic kidney disease

OBJECTIVE

The aim of this audit was to evaluate the degree of glomerular filtration rate (GFR) among inpatients and outpatients in a District General Hospital, with special attention given to laboratory testing and impact on health delivery.

BACKGROUND

UK Chronic Kidney Disease guidelines recommend that investigation of renal function should be accompanied by an estimation of GFR (eGFR) in order to identify and manage patients with chronic kidney disease (CKD). The estimated GFR forms the basis for classification of CKD and appropriate action plans for patient management and follow-up.

METHOD

A retrospective audit of 8160 results from a predominantly British Caucasian population was carried out; extracting creatinine results from two isolated months in years 2001 and 2004. The estimated GFR (eGFR) was calculated using the MDRD formula. The data were classified according to demography, serum creatinine and eGFR. Patients from the 2001 database were classified according to eGFR and those with a value of <60 mL/min/1.73 m(2) were followed up in 2004.

RESULTS

The difference in eGFR between the men and women was significantly different with medians (confidence intervals) of 80.1 (41-109) and 64.4 (30-84.6) (p<0.0001), respectively. There was an inverse association between age and eGFR in both genders (p<0.0001), with a decrease in eGFR of around 7 % for each decade increase in age. 1926 patients (24 %) of results studied had eGFR <60 mL/min, of whom 64 % were females and 36 % males. Follow-up of patients with eGFR<60 mL/min from 2001 showed that 4 % progressed to stages 4 and 5 CKD.

CONCLUSION

eGFR is inversely associated with increasing age and female gender. MDRD derived eGFR fails to completely compensate for age and gender variations and thus different action limits may be required. Small but significant numbers of patients progressed to stages 4 and 5 CKD. Additional clarity in describing "progressive fall in eGFR" in the guidelines would improve identification of the population most at risk.

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.

Delivery patterns of recommended chronic kidney disease care in clinical practice: administrative claims-based analysis and systematic literature review

BACKGROUND

Clinical practice guidelines for management of chronic kidney disease (CKD) have been developed within the Kidney Disease Outcomes Quality Initiative (K/DOQI). Adherence patterns may identify focus areas for quality improvement.

METHODS

We retrospectively studied contemporary CKD care patterns within a private health system in the United States, and systematically reviewed literature of reported practices internationally. Five hundred and nineteen patients with moderate CKD (estimated GFR 30-59 ml/min) using healthcare benefits in 2002-2005 were identified from administrative insurance records. Thirty-three relevant publications in 2000-2006 describing care in 77,588 CKD patients were reviewed. Baseline demographic traits and provider specialty were considered as correlates of delivered care. Testing consistent with K/DOQI guidelines and prevalence of angiotensin converting enzyme inhibitor/angiotensin receptor blocker (ACEi/ARB) medication prescriptions were ascertained from billing claims. Care descriptions in the literature sample were based on medical charts, electronic records and/or claims.

RESULTS

KDOQI-consistent measurements of parathyroid hormone (7.1 vs. 0.6%, P = 0.0002), phosphorus (38.2 vs. 1.9%, P < 0.0001) and quantified urinary protein (23.8 vs. 9.4%, P = 0.008) were more common among CKD patients with versus without nephrology referral in the administrative data. Nephrology referral correlated with increased likelihood of testing for parathyroid hormone and phosphorus after adjustment for baseline patient factors. Use of ACEi/ARB medications was more common among patients with nephrology contact (50.0 vs. 30.0%; P = 0.008) but appeared largely driven by higher comorbidity burden. The literature review demonstrated similar practice patterns.

CONCLUSIONS

Delivery of CKD care may be monitored by administrative data. There is opportunity for improvement in CKD guideline adherence in practice.

Reengineering Clinical Operations in a Medical Practice to Optimize the Management of Anemia of Chronic Kidney Disease

OBJECTIVES

To describe the clinic design, clinical evaluations, and treatment approaches used in a multidisciplinary clinic for management of anemia of chronic kidney disease (CKD), and to evaluate several selected clinical outcomes associated with this approach to anemia management.

SETTING

University-affiliated, division of nephrology, outpatient multidisciplinary model CKD clinic headed by a clinical pharmacist.

PATIENTS

One hundred sixty-six patients with anemia of CKD who were referred by nephrologists and primary care providers to the multidisciplinary clinic from March 1, 2002-July 31, 2004.

MEASUREMENTS AND MAIN RESULTS

Patients received darbepoetin alfa dosed on an every-other-week basis. If patients were already receiving once-weekly recombinant human erythropoietin (r-HuEPO), the darbepoetin alfa dose was calculated by using the darbepoetin alfa package insert conversion table. If patients were naïve to previous erythropoietic therapy, the darbepoetin alfa dose was either 60 microg or 0.7 microg/kg. The dose and frequency of darbepoetin alfa and oral iron supplements were adjusted to achieve the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI) targets for hemoglobin levels and iron measures. The primary outcome analyzed was the proportion of patients with at least 30 days of treatment who achieved a target hemoglobin level of 11.0 g/dl or greater. Of 128 patients who received at least 30 days of treatment, 100 (78%) attained the hemoglobin level (mean +/- SD 11.7 +/- 7 g/dl). Ninety-nine of 128 patients were originally naïve to erythropoietic therapy; 77 (78%) of these 99 patients achieved the hemoglobin target in a mean +/- SD of 7.9 +/- 7.5 weeks. These data contrast with the data of 29 patients seen in the year previous to the reengineered clinic process, whereby only 12 (41%) of these comparable patients reached hemoglobin target with r-HuEPO therapy. Of the 77 previously erythropoietic-naïve patients, 82% were receiving darbepoetin alfa every other week, 14% every 3 weeks, and 4% every 4 weeks at the time the hemoglobin target was achieved. Oral iron administration significantly increased the chance of achieving the K/DOQI targets for hemoglobin and iron.

CONCLUSION

Redefining roles and practices of members of a clinical practice and reengineering processes for anemia management were effective in achieving and maintaining target hemoglobin and iron levels.

Prevalence and predictors of cardiovascular calcium in chronic kidney disease (from the Prospective Longitudinal RRI-CKD Study)

Although the determinants of cardiovascular calcium have been well described in dialysis patients, the prevalence and predictors in predialysis chronic kidney disease (CKD) are less known. One hundred six patients with CKD from the Renal Research Institute-CKD Study underwent multidetector computed tomography for the assessment of calcium deposition at the level of coronary arteries, thoracic aorta, aortic valve, and mitral valve. Cardiovascular risk factors and renal function-related parameters (glomerular filtration rate, glomerular filtration rate slope, serum creatinine, serum urea nitrogen, hemoglobin, albumin, calcium, phosphate, and parathyroid hormone) were included in multivariate regression models to predict cardiovascular calcium. Prevalences of calcium deposition at the level of coronary arteries, thoracic aorta, aortic valve, and mitral valve were 69%, 46%, 39%, and 16%, respectively. On multivariate analysis, coronary artery calcium score was predicted by age (p < 0.0001), gender (p = 0.0001), diabetes (p = 0.024), and history of coronary artery disease (p = 0.016), but not by renal function related parameters. Similarly, renal function related parameters were not predictive of aortic or valvular calcium. In conclusion, predialysis CKD is associated with a high prevalence of cardiovascular calcium. The extent of cardiovascular calcium in patients with predialysis CKD is related to some of the traditional risk factors for atherosclerosis but not to indexes of abnormal renal function or progression in renal dysfunction.

Vascular calcification in patients with chronic kidney disease

Chronic kidney disease (CKD) represents an extremely common condition, and cardiovascular diseases are frequently reported in this patient population. Traditional risk factors are not accurate prognostic predictors in CKD patients, and new potential markers to predict the cardiovascular involvement in uremic patients need to be identified. Vascular calcification (VC) represents a hallmark of the atherosclerotic process in CKD. This review summarizes the processes responsible for VC (particularly focusing on the mechanisms operative in the presence of renal dysfunction), discusses the utility of computer tomography modalities in the detection of VC in patients with CKD, and reports the potential role of VC as pathophysiological link between kidney disease and cardiovascular events.

Vascular calcification in patients with renal failure: culprit or innocent bystander?

The mortality from cardiovascular events in CKD and dialysis patients is substantially higher than in the general population. VC is ubiquitous and progresses rapidly in this patient population. Although there has been progress in the understanding of the pathogenesis and correlates of VC, much work needs to be done in this area. The role of calcium and, probably, phosphate (obligatory participants) is unquestionable, but the understanding of the paracrine and molecular determinants of VC in renal failure is continuously evolving. VC is probably a dynamic process resulting from the imbalance between molecules that promote and those that inhibit VC. The understanding of latter area has recently evolved with identification of new signaling pathways with molecules such as osteoprotegerin, fetuin-A, and MPG. From a clinical perspective, new modalities such as EBCT and MDCT allow noninvasive detection and quantification of VC. VC may represent a potential useful index for prognostic stratification and treatment planning in patients who have renal failure. At present, however, the data on the prognostic value of VC are available only in populations of patients who have normal renal function. Large-scale, prospective, observational studies should be designed to identify the determinants of VC and to define the prognostic role of calcium scoring in cohorts of patients who have predialysis CKD and with ESRD.

Nutrition in Chronic Heart Failure With Coexisting Chronic Kidney Disease

BACKGROUND AND RESEARCH OBJECTIVES

Patients with heart failure (HF) may be predisposed to malnutrition. Little is known about the nutritional status of patients with HF, particularly patients who have coexisting major medical conditions such as chronic kidney disease. The purposes of this study were to (1) describe the nutritional status of 211 patients with chronic HF, (2) examine relationships between nutrition variables and health-related quality of life, and (3) evaluate the nutritional status of the subset of HF patients with coexisting chronic kidney disease.

SUBJECTS AND METHODS

The sample included 211 patients with chronic HF recruited for a larger study about health-related quality of life. Clinical data were retrieved retrospectively from the computerized medical records system at the study site.

RESULTS AND CONCLUSIONS

Mean body mass index of the 122 patients for which height was available was 31.4, and no differences in body mass index were noted among patients with varying New York Heart Association class functional status. Evaluation of the mean laboratory values indicated that patients had abnormal elevations of serum glucose, hemoglobin A1C, creatinine, and low-density lipoprotein cholesterol. Higher hemoglobin A1C levels were significantly correlated with poorer health-related quality-of-life scores, although the magnitude of the correlations was modest. Estimated glomerular filtration rate indicated that 54 (27%) of the HF patients likely had coexisting chronic kidney disease, and these patients had significantly lower serum albumin and worsening anemia. The results indicate the need for future prospective studies that incorporate evaluation of nutritional status and the ways in which coexisting chronic kidney disease influences outcomes.

Quality of life in chronic kidney disease (CKD): a cross-sectional analysis in the Renal Research Institute-CKD study

BACKGROUND

Health-related quality of life (QOL) is an important measure of how disease affects patients' lives. Dialysis patients have decreased QOL relative to healthy controls. Little is known about QOL in patients with chronic kidney disease (CKD) before renal replacement therapy.

METHODS

The Medical Outcomes Study Short Form-36 (SF-36), a standard QOL instrument, was used to evaluate 634 patients (mean glomerular filtration rate [GFR], 23.6 +/- 9.6 mL/min/1.73 m2 [0.39 +/- 0.16 mL/s/1.73 m2]) enrolled in a 4-center, prospective, observational study of CKD. SF-36 scores in these patients were compared with those in a prevalent cohort of hemodialysis (HD) patients and healthy controls (both from historical data). QOL data also were analyzed for correlations with GFR and albumin and hemoglobin levels in multivariable analyses.

RESULTS

Patients with CKD had higher SF-36 scores than a large cohort of HD patients (P < 0.0001 for 8 scales and 2 summary scales), but lower scores than those reported for the US adult population (P < 0.0001 for 7 of 8 scales and 1 of 2 summary scales). Patients with CKD stage 4 had lower QOL scores than patients with CKD stage 5, although differences were not significant. Hemoglobin level was associated positively with higher mental and physical QOL scores (P < 0.05) in all individual and component scales except Pain.

CONCLUSION

SF-36 scores were higher in this CKD cohort compared with HD patients, but lower than in healthy controls. GFR was not significantly associated with QOL. Hemoglobin level predicted both physical and mental domains of the SF-36. Longitudinal studies are needed to define at-risk periods for decreases in QOL during progression of CKD.

Patterns of medication use in the RRI-CKD study: focus on medications with cardiovascular effects

BACKGROUND

Patients with chronic kidney disease (CKD) stages 2-5 are known to suffer numerous complications and co-morbidities associated with kidney disease. The medication prescription patterns in this population are not well understood. We report on prescription data collected as part of a multicentre longitudinal study in patients with CKD, with a focus on medications with cardiovascular or cardioprotective effects.

METHODS

Patients were recruited from four academic nephrology centres in the USA, with patient recruitment from June 2000 to March 2002. Medication data were captured at the time of first enrollment into the study. Individual medications were classified into medication groups, and those with predominant cardioprotective effects or for prevention of progression of kidney disease (e.g. medications for treatment of anaemia, lipid-lowering agents, antihypertensives, statins, etc.) were recorded for analysis. Descriptive statistics were used for medication prescription according to baseline demographics and co-morbidities. Predictors of epoetin and iron use were determined by logistic regression adjusting for age, race, sex, diabetes, glomerular filtration rate (GFR), haemoglobin and serum albumin.

RESULTS

Medication data were available for 619 patients with stages 2-5 CKD. Patients were 60.6+/-16.0 years of age, and were prescribed 8+/-4 (range 1-28) medications. Overall, the proportion of patients prescribed different classes of medications included epoetin (20%), intravenous iron (13%), HMG-CoA reductase inhibitors (16%), angiotensin-converting enzyme (ACE) inhibitors (44%), angiotensin receptor blockers (13%), beta-blockers (46%), calcium channel blockers (52%) and aspirin (37%). There was a low use of epoetin (45%) and iron (20%) in patients with anaemia. Only 24% of patients with coronary artery disease were prescribed statins, and ACE inhibitors and angiotensin receptor blockers were used in only 58 and 23% of diabetic patients with proteinuria. Positive predictors of epoetin and iron therapy included white race and diabetes. Higher GFR and higher serum albumin were associated with lower odds of being prescribed epoetin. White race and diabetics were more likely to be prescribed iron.

CONCLUSIONS

This study provides an overview of prescription practices in a cohort of CKD patients. Substantial underutilization of certain classes of cardioprotective medications is apparent, and systematic educational efforts in this direction may well prove worthwhile to impact outcomes.