NDT Advance Access originally published online on November 24, 2006
Nephrology Dialysis Transplantation 2007 22(3):833-838; doi:10.1093/ndt/gfl701
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Effectiveness of a chronic kidney disease clinic in achieving K/DOQI guideline targets at initiation of dialysis—a single-centre experience
1University of Colorado Health Sciences Center, 2Veterans Affairs Denver Healthcare System, Denver, CO and 3CSC, Inc., Santa Barbara, CA, USA
Correspondence and offprint requests to: Michel Chonchol, MD, Division of Renal Diseases and Hypertension, University of Colorado Health Sciences Centre, Denver, CO 80262, USA. Email: Michel.Chonchol{at}uchsc.edu
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Abstract |
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Background. Limited data exist about the effects of chronic kidney disease (CKD) clinics on quality-of-care indicators in patients before initiation of dialysis.
Methods. A single-centre retrospective chart review study was conducted on all patients who initiated dialysis at the Veterans Affairs Denver Healthcare System between 2000 and 2005. Patients initiating dialysis were evaluated at the start of dialysis and 12 months after dialysis initiation, as a function of care provided by nephrologists in training (renal-hypertension clinic) vs a trained renal nurse practitioner (CKD clinic).
Results. Data were available for 77 patients followed in the CKD clinic and 36 in the renal-hypertension clinic. There were no major demographic differences between the cohorts at the time of clinic referral. The length of follow-up before dialysis did not differ significantly between the cohorts (10.7±9.8 months for the patients in the CKD clinic cohort and 13.6±16.0 months for the patients in the renal-hypertension clinic cohort, P=0.3299). At the initiation of dialysis, patients followed in the CKD clinic had higher haemoglobin (11.6±1.5 vs 10.8±1.7 g/dl, P=0.0239) and serum albumin (3.4±0.5 vs 3.0±0.7 g/dl, P=0.0020) concentrations. More of the CKD clinic patients had a functioning permanent vascular access (P<0.0001). The number of all-cause hospitalizations in the 12 months after initiation of dialysis was significantly lower in the CKD clinic group (P=0.0024), but no significant differences were noted in all-cause mortality.
Conclusions. Our data indicate that a single experienced renal nurse practitioner, working to a protocol, is more likely to adhere to guidelines than are multiple nephrology trainees rotating through a nephrology clinic.
Keywords: chronic kidney disease; CKD clinic; NKF-K/DOQI guidelines; quality of care
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Introduction |
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In the United States, an estimated 11% of the population has chronic kidney disease (CKD), and consequently the prevalence and incidence of end-stage renal disease (ESRD) are increasing [1, 2]. Extensive data exist supporting early evaluation of patients with CKD by nephrologists, making it possible to better manage uraemic complications and prepare the patient for renal replacement therapy [3–5]. Much emphasis has been placed on improving the quality of care for this population by encouraging early referrals from primary care physicians and developing guidelines for care of CKD patients, for example, in the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-K/DOQITM) [2, 6]. Despite these efforts, the rates of annual hospitalization and mortality for ESRD patients remain high, and have not changed significantly in recent years [7].
Several Canadian studies [3, 5, 8] have reported the usefulness of multi-disciplinary care teams in the management of CKD patients; however, even these multi-disciplinary models [5] with teams that include nephrologists, nurse educators and dieticians have failed to achieve the target rates for anaemia management and vascular access placement recommended in the K/DOQI guidelines [2, 6] for a significant fraction of patients. There are very few published reports describing the effects of CKD clinics based on specific care models on outcomes in chronic dialysis patients in US centres.
The objective of this retrospective chart review study was to examine outcomes in patients with CKD who had been exposed to two different clinical care models and who then initiated dialysis at the Denver Veterans Affairs Medical Center (VAMC). Care for one group of patients was managed by nephrologists in training under the supervision of board-certified nephrologists (renal-hypertension clinic), whereas patients in the other group (CKD clinic) were cared for by a trained renal nurse practitioner who aggressively followed the K/DOQI guidelines [6], with management collaboratively reviewed by board-certified nephrologists. We evaluated a series of quality outcomes in these two cohorts of patients, including laboratory parameters and access type at initiation of chronic dialysis as well as all-cause hospitalization and all-cause mortality within the first 12 months after initiation of chronic dialysis.
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Subjects and methods |
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Patient population
A retrospective review was performed on charts of all of the 113 consecutive incident chronic dialysis patients >18 years of age who initiated dialysis at VAMC in Denver, CO, USA between 1st July 2000 and 30th June 2005. All charts were classified as adequate for analysis in that they contained information from the initial appointment with a nephrologist and from the last clinic visit before initiation of chronic dialysis, as was follow-up information on hospitalization and mortality at 12 months after initiation of dialysis. This study was approved by the University of Colorado Institutional Review Board.
All patients referred for management of CKD at Denver VAMC are seen by a board-certified nephrologist for an initial visit, and then are assigned to either the renal-hypertension clinic or the CKD clinic. Patients are not assigned randomly to the clinics, but are assigned as needed to maintain a consistent distribution of the total numbers of consults performed in the two clinics. For capacity-related reasons, patients are assigned to the CKD clinic in a 2:1 ratio relative to the renal-hypertension clinic. Once dialysis is started, patients are cared for in the ESRD unit of the Denver VAMC.
Patient care
Care in the CKD clinic adheres strictly to K/DOQI guidelines [6], and in addition, the renal nurse practitioner addresses the psychosocial and learning needs of the patients in the CKD clinic. The care of patients exposed to the renal-hypertension clinic is not protocol-driven, although there is consensus in this clinic regarding the following treatment targets: (i) blood pressure control (<130/80 mmHg); (ii) maintenance of calcium and phosphorus levels according to the K/DOQI Clinical Practice Guidelines for Bone Mineral Metabolism and Disease in Chronic Kidney Disease [9]; (iii) preservation of nutritional status (serum albumin >3.4 g/dl); (iv) control of anaemia (haemoglobin >11.0 g/dl) and (v) placement of a permanent vascular access prior to the initiation of haemodialysis. Patients in both groups have access to all services provided by the Denver VAMC, including laboratory, pharmacy, dietary and interventional radiology services as well as vascular surgery consultation.
Data collection
All data for this study were obtained from patient records maintained in the Veterans Affairs (VA) Information Systems and Technology Architecture (VISTA) system. This computerized system, used throughout the VA medical care organizations, maintains patient-level data, including demographic characteristics, laboratory measurements, diagnosis and intervention information, for all VA patient encounters.
Data on blood pressure (BP) was noted and was measured by the clinic staff. Laboratory measurements included were haemoglobin, serum albumin, calcium and phosphorus. The glomerular filtration rate (GFR) was estimated using the abbreviated modification of diet in renal disease (MDRD) formula at the time of clinic referral. Data on the usage of erythropoietin and phosphate binders as well as receipt of education on renal replacement therapies (watching a video prepared by the NKF) and dietary counselling (referral to a dietician) were collected. Also, the number of all-cause hospitalizations within the first year of starting dialysis and the status (alive, dead or transplanted) 1 year after initiation of dialysis were recorded from the computerized hospital medical records.
Statistical analysis
Categorical data were summarized using counts and percentages. Continuous data were presented with means and SDs. Clinical characteristics, laboratory parameters and types of vascular access in the two groups were compared using Fisher's exact tests for categorical or dichotomized numerical variables and Wilcoxon rank sum tests for continuous variables. Hospitalization during 12 months of clinic exposure was recorded as a binary yes/no variable as well as by a count, and patient status at 1 year after initiation of dialysis was classified as dead, alive or transplanted. Change measures were constructed by subtracting values for systolic BP (SBP), diastolic BP (DBP) and laboratory parameters (haemoglobin, albumin, calcium and phosphorus) obtained on initiation of dialysis from values obtained during the initial clinic visit. Relative differences between the time points were evaluated by Wilcoxon rank sum tests. To evaluate the risks of hospitalization in the two groups while controlling for possible differences in condition among patients at the initiation of dialysis, a backward stepping logistic model was performed, in which SBP, DBP, access type (permanent vs not permanent), haemoglobin, erythropoietin use, albumin, calcium, phosphorus and estimated GFR at initial visit, were included as covariates. All tests were two-sided, with statistical significance defined as P<0.05. All analyses were conducted using SAS, version 8.2.
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Results |
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Patient characteristics
Of the 113 patients analysed, only one patient initiated peritoneal dialysis, whereas the remaining 112 were started on haemodialysis. Of the patients, 77 had been followed in the CKD clinic and 36 in the renal-hypertension clinic. No significant differences were noted between the groups in age at initial visit, gender, race or follow-up time in the clinic before initiation of dialysis (Table 1). Causes of kidney disease differed between the clinic groups: the group of patients exposed to the CKD clinic contained a higher proportion of patients with diabetes compared with the group exposed to the renal-hypertension clinic (77.9 vs 52.8%, P=0.0087). The group of patients exposed to the CKD clinic also had a lower mean estimated GFR at the initial visit (16.3±5.8 vs 22.9±10.8 ml/min/1.73 m2, P<0.001).
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Clinical and laboratory parameters
Table 2 presents clinical and laboratory parameters at the first clinic visit and at initiation of dialysis. At the time of their first visit, patients exposed to the renal-hypertension clinic had higher SBPs (153.7±25.6 vs 142.3±19.6 mmHg, P=0.0173) and DBPs (83.0±15.5 vs 71.2±12.7 mmHg, P<0.0001) than patients exposed to the CKD clinic.
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At initiation of dialysis, patients exposed to the CKD clinic had higher haemoglobin (11.6±1.5 vs 10.8±1.7 g/dl, P=0.0239) and albumin (3.4±0.5 vs 3.0±0.7 g/dl, P=0.0020) levels than patients exposed to the renal-hypertension clinic. At this time also, higher percentages of patients exposed to the CKD clinic were receiving erythropoietin replacement therapy (54.5 vs 27.8%, P=0.0089) and/or phosphate binders (70.1 vs 44.4%, P=0.0124). Furthermore, at the initiation of dialysis a higher proportion of patients exposed to the CKD clinic had received dietary counselling (57.1 vs 16.7%, P<0.0001) and/or dialysis education (92.2 vs 38.9%, P<0.0001).
Significant differences in change measures between the initial clinic visit and initiation of dialysis were seen only for DBP, haemoglobin and albumin. Patients exposed to the renal-hypertension clinic had greater decrease in DBP (7.1 vs 1.5 mmHg, P=0.0440), haemoglobin (1.3 vs 0.1 g/dl, P=0.0093) and serum albumin (0.2 vs 0.1 g/dl, P=0.0051) over this time period than did patients exposed to the CKD clinic.
Haemodialysis vascular access
A higher percentage of patients in the CKD clinic had a functioning permanent vascular access (arteriovenous fistula or arteriovenous graft) in place at the time of starting haemodialysis compared with patients exposed to the renal-hypertension clinic (61.9 vs 19.4%, P<0.0001) (Figure 1). Patients were also classified as lacking a permanent access if they initiated haemodialysis with the use of a tunnelled dialysis catheter only, or a tunnelled catheter with a maturing arteriovenous fistula or graft. The distribution of access types in the two groups is shown in Figure 2.
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All-cause hospitalization and all-cause mortality
The difference in hospitalizations between the groups over the 12 months after initiation of dialysis was significant. One or more hospitalizations was noted in 39 (50.6%) and 31 (86.1%) patients followed in the CKD and renal-hypertension clinics, respectively (P<0.0001). The number of hospitalizations for the patients who had been followed in the renal-hypertension clinic was significantly larger than for those followed in the CKD clinic (P=0.0024) (Figure 3). After adjustment for the covariates mentioned, a logistic model showed a significantly greater likelihood of occurrence of one or more hospitalizations in the renal-hypertension clinic group (adjusted OR: 3.87; 95% CI: 1.3–11.7). At 1 year after initiation of dialysis, seven patients in the CKD clinic group had died and four had had transplants, whereas five patients in the renal-hypertension clinic group had died and one had had a transplant. There was no statistically significant difference in all-cause mortality between clinic groups (P=0.5161).
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Discussion |
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This is one of the few published studies to compare quality outcomes of CKD care administered by a nurse practitioner who adheres closely to the K/DOQI guidelines for patients with CKD compared with a general renal-hypertension clinic. Care was found to be more favourable in all respects in the CKD clinic than in the renal-hypertension clinic.
Anaemia, hyperphosphataemia and hypoalbuminaemia are widely prevalent and generally under treated in patients with CKD [9, 10]. At initiation of dialysis for patients in the United States, the mean haematocrit and serum albumin have been reported to be 27.9 and 3.2 g/dl, respectively [10]. Haemoglobin levels <8.8 g/dl and the presence of low serum albumin at the initiation of dialysis are predictive of morbidity and mortality [11–13]. In addition, Kestenbaum et al. [14] recently noted an independent association between elevated serum phosphate levels and the risk of mortality and myocardial infarction amongst a cohort of veterans with CKD not requiring dialysis. In the present study, patients followed in the CKD clinic had higher haemoglobin levels, percentage of erythropoietin usage and serum albumin at the initiation of dialysis compared with patients followed in the renal-hypertension clinic. Furthermore, mean phosphorus levels in both groups at the initiation of dialysis were above the K/DOQI target range [15]. Evidently, phosphorus control is difficult to achieve, even in a dedicated CKD clinic where 70% of the cohort was receiving phosphate binders.
A functioning permanent access was more commonly present at the initiation of dialysis in the CKD clinic group. Both groups had the same opportunity for access to the vascular surgery team. Up to 62% of the cohort followed in the CKD clinic was able to initiate dialysis using a functioning permanent access. These findings are vastly different from those reported from the Canadian multi-disciplinary kidney disease clinics; half of their patients started dialysis using a catheter [5]. These different results may be related to the fact that our cohort consist almost entirely of a male population. The finding that the arteriovenous fistula failure rate is greater in women than men, independent of other risk factors, has been reported by others [16, 17]. Although, the significantly higher percentage of arteriovenous fistula placement in the CKD group was not affected by the higher prevalence of diabetes.
All-cause hospitalizations were lower during the first 12 months after initiating dialysis in patients who had been followed in the CKD clinic. Catheter-related complications are an important cause of hospitalization and carry a high relative risk of death [18, 19]. In view of the low rate of catheter use in the CKD clinic, the lower rate of hospitalization in this group may be due to a low incidence of access-related complications, although this hypothesis cannot be confirmed because the reasons for hospitalization were not collected.
Limitations
There are several limitations to this study. It was a chart review and not a prospective analysis, the sample size was small and the patient population was mostly male. Patients were not randomized for clinic referral, but were allocated to the two clinics in such a manner as to balance clinic workloads. Significant differences between groups were recorded in mean estimated GFR at the first visit and in prevalence of diabetes, although in both groups the GFR was in the ‘severely reduced’ range according to the NKF-KDOQI classification [6]. The patients exposed to the CKD clinic, on average, had poorer prognostic indicators, including higher frequency of diabetes and lower GFR at the initial nephrologist visit, and therefore, any selection bias would have tended to favour the renal-hypertension clinic. The fact that poorer outcomes were nonetheless noted in patients initiating dialysis from the renal-hypertension clinic thus emphasizes the favourable effects of the approach employed in the CKD clinic.
Because resources to support peritoneal dialysis were not readily available to this population, most of the patients were initiated on haemodialysis as the renal replacement modality and only one was initiated on peritoneal dialysis. The consistency of staffing differed: the renal-hypertension clinic is staffed by nephrologists in training who rotate through the clinic in 3-year cycles, whereas the CKD clinic is staffed by a highly trained nurse practitioner who has been working in the VA system for more than 10 years.
Finally, it was not possible to be certain that all hospitalizations were accounted for because some veterans might have gone to hospitals other than the Denver VAMC, where we would not have had access to their records. Nevertheless, this study provides support for the idea that a dedicated CKD clinic may improve outcomes in dialysis patients. Addition of costs to this comparison of care models would have been valuable, but this information was not available to us.
In summary, physicians in general nephrology clinics must deal with a variety of renal issues unrelated to preparation for dialysis, including workup and management of nephrotic and nephritic syndromes and treatment of resistant hypertension and electrolyte abnormalities. Furthermore, nephrologists often must balance out-patient clinical practices with in-patient consultations as well as dialysis centre management. The potential for lagging on some aspects of CKD care is high, especially in very busy practices. Having a dedicated CKD clinic may help to streamline routine care and improve the quality of care for patients nearing dialysis by focusing on meeting K/DOQI guidelines. In addition, staff of a dedicated CKD clinic are likely to be familiar with all supportive resources and to support multi-disciplinary care. Other potential advantages of referring all patients with CKD to a dedicated CKD clinic include the ability to follow trends in outcomes and to establish effective protocols for patient care. It appears likely that formal protocols, rather than a consensus approach, will be required for all aspects of CKD care in order to increase the number of patients achieving the recommended targets.
Conflict of Interest Statement. None declared.
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Accepted in revised form: 27.10.06
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