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Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Objective

Little is known about the patterns of use of initial kidney replacement therapies among patients with lupus nephritis (LN) end-stage renal disease (ESRD). We aimed to identify sociodemographic and clinical factors associated with variation in initial kidney replacement therapies among LN ESRD patients.

Methods

Patients with incident LN ESRD (1995–2006) were identified in the US Renal Data System. Age, sex, race, ethnicity, medical insurance, employment status, residential region, clinical factors, and comorbidities were considered as potential predictors of ESRD treatment choice, i.e., peritoneal dialysis (PD), hemodialysis (HD), or preemptive kidney transplantation in age-adjusted and multivariable-adjusted logistic regression analyses.

Results

Of the 11,317 individuals with incident LN ESRD, 82.0% initiated HD, 12.2% initiated PD, and 2.8% underwent preemptive kidney transplantation. Receiving initial PD was significantly associated with earlier calendar year, female sex, higher albumin and hemoglobin levels, and lower serum creatinine levels. African Americans (versus whites), Medicaid beneficiaries and those with no health insurance (versus private insurance), and those unemployed (versus employed) had significantly reduced PD initiation. Comorbidities including congestive heart failure, peripheral vascular disease, and the inability to ambulate were also associated with decreased PD. Many sociodemographic and clinical factors favoring PD were associated with preemptive kidney transplant (versus dialysis) as well.

Conclusion

Few patients with LN ESRD receive initial PD or preemptive kidney transplantation. Race, ethnicity, employment, and medical insurance type are strongly associated with initial kidney replacement therapy choice. Future studies need to investigate the appropriateness of sociodemographic and clinical variation and the comparative effectiveness of kidney replacement therapies for LN ESRD.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Despite advancements in therapies for systemic lupus erythematosus (SLE) over the past 2 decades, the annual incidence of lupus nephritis (LN)–related end-stage renal disease (ESRD) has not declined (1–3). Approximately 20% of LN patients advance to ESRD over a 10-year period (4–6). As they approach ESRD, patients and their providers must choose among kidney replacement options, including hemodialysis (HD), peritoneal dialysis (PD), or preemptive kidney transplantation. Although HD and PD have been offered to ESRD patients for several decades, little is known about factors that influence the choice of initial dialysis modality, particularly for LN ESRD patients. Immunosuppressant use, underlying SLE disease activity, preexisting comorbid illness, and availability of dialysis services and transplantation certainly all deserve consideration as this decision is made.

While kidney transplantation is the best long-term option for patients with ESRD, the vast majority of LN ESRD patients initiate dialysis first, due to both the imbalance of supply and demand of donor organs (7) and the desire to delay transplantation following lupus disease activity (8). In recent years, <3% of LN ESRD patients in the US received a preemptive kidney transplant without initial dialysis (3). It remains unclear whether long-term outcomes among LN ESRD patients differ according to the kidney replacement option chosen, in particular the 2 dialysis modalities (6–8). Although there is a paucity of prospective data comparing infection rates among LN ESRD patients receiving HD compared to PD, a few studies have suggested an increased risk for peritonitis and higher mortality rates among SLE patients receiving PD (7, 9, 10). Past studies of the influence of dialysis modality upon SLE disease activity have also yielded inconsistent results (7–13). Predialysis comorbidities, especially cardiovascular conditions, have been associated with increased mortality rates, particularly among LN ESRD patients receiving PD (9). LN ESRD patients appear to do well after kidney transplant, however, with low SLE activity and rates of recurrent LN (14–17). In addition to clinical factors, geographic access to dialysis and transplantation may influence patient selection of kidney replacement therapy for LN ESRD, although this has never been studied. In the present study, we investigated clinical and sociodemographic determinants of the choice of initial kidney replacement therapy among LN ESRD patients in the US from 1995–2006.

Significance & Innovations

  • This is the first and only large observational study of initial kidney replacement therapy among patients with end-stage renal disease (ESRD) due to lupus nephritis (LN), with more than 11,000 patients throughout the US from 1995–2006.

  • Understanding the sociodemographic predictors of initial dialysis modality among LN ESRD patients is increasingly relevant since, in 2011, the Centers for Medicare and Medicaid Services ESRD payment system changed, thereby effectively providing strong incentives to increase utilization of home dialysis modalities including peritoneal dialysis.

  • These findings will lead to investigations of the appropriateness of this variation and the comparative effectiveness of these therapies for LN ESRD patients.

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Data sources.

The US Renal Data System (USRDS) is the registry of patients with ESRD and includes all ESRD patients in the US who receive any kidney replacement therapy as dialysis or kidney transplantation (13). For each new patient at enrollment, the attending nephrologist is required to complete the Medical Evidence Report Form (Centers for Medicare and Medicaid Services [CMS] 2728). The date of first service is derived from the earliest of start dates reported on the Medical Evidence Report form, the date of kidney transplant as reported on a CMS or Organ Procurement Transplant Network form, the Medical Evidence Report, a hospital inpatient claim, or the date of the first Medicare dialysis claim (13).

Study population.

As previously described (3), we identified all individuals ages 18–100 years with SLE (International Classification of Diseases, Ninth Revision code 710.0) identified as the cause of ESRD at enrollment in the USRDS from January 1, 1995 to December 31, 2006. From the USRDS, we obtained information concerning patient demographics, including age, sex, race (white, African American, Asian/Pacific Islander, or American Indian), Hispanic ethnicity, and US state or US islands (including Puerto Rico, US Virgin Islands, American Samoa, and Guam) at the time of initiation of ESRD treatment. The following data for each patient at ESRD onset were recorded: body mass index (BMI); serum levels of creatinine, hemoglobin, and albumin; type of medical insurance prior to ESRD (Medicare, Medicaid, Department of Veterans Affairs, employer group, or none); and current employment status (employed/unemployed). Comorbid diabetes mellitus, hypertension, malignancy, congestive heart failure, cerebrovascular disease, coronary artery disease, chronic obstructive pulmonary disease, peripheral arterial disease, as well as current cigarette smoking, current drug abuse, and inability to ambulate or to transfer (as documented on the Medical Evidence Report forms) were also included.

The outcomes of study were the specific types of initial kidney replacement therapy, i.e., HD, PD, or preemptive kidney transplant. Patients with missing data concerning the type of initial kidney replacement therapy were excluded from all analyses. Data were obtained from the USRDS through a data use agreement, and data are shown in accordance with USRDS reporting policies (cell sizes below 11 have been suppressed).

Statistical analysis.

We examined the clinical and sociodemographic characteristics of US patients with ESRD due to LN according to the type of initial kidney replacement therapy they received: HD, PD, or preemptive kidney transplantation at ESRD onset. In univariable analyses, t-tests for continuous variables and chi-square or Fisher's exact tests for categorical variables were used to examine the distributions of these variables according to the 2 outcomes: initial PD (versus HD) and preemptive transplantation (versus any dialysis). Separate age-adjusted and then multivariable logistic regression models were used to identify those variables that were significantly associated with receiving either initial PD (versus HD) or preemptive transplantation (versus any dialysis and compared to HD only) among the sociodemographic and clinical variables. As the relationships between clinical laboratory values and outcomes were not linear, we employed tertile cutoffs for the serum values, and clinically accepted cutoffs for BMI. In the multivariable models, we tested for potential interactions among the variables, in particular for modification of associations of race and ethnicity by other variables. All the P values were calculated with a 2-sided significance level of 0.05. Data analyses were performed using SAS software, version 9.2. The Partners' Healthcare Institutional Review Board reviewed this study protocol and granted it a waiver as human subjects' exempt research.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

We identified 11,317 individuals with complete data concerning initial kidney replacement therapy for ESRD due to LN between January 1, 1995 and December 31, 2006 (Table 1). The majority (85%) of patients used HD at the onset of ESRD, while 12.2% used PD and 2.8% had a preemptive kidney transplant. From 1995 to 2006, there was a steady and significant decline in the proportion of incident LN ESRD patients begun on PD (from 16.8% to 9.7%), with a corresponding increase in those started on HD. Compared to patients started on HD (mean ± SD age 41.2 ± 15.1 years), patients started on PD were of comparable age (mean ± SD age 41.0 ± 13.1 years), although the age range was slightly different with a higher proportion in the ages 30–50 years group. Patients who were initiated on PD had slightly higher serum albumin and hemoglobin levels. Fewer individuals starting on PD than on HD had serum creatinine levels >8.4 mg/dl and fewer had BMIs >25 kg/m2. Those who received initial PD were more likely to be women and of Asian or white race than those initiating HD. A higher proportion of initial PD compared to HD patients also had private medical insurance, with correspondingly lower proportions of individuals with Medicaid, Medicare, or no medical insurance. More initial PD than HD patients were employed at ESRD onset and there was some variation in geographic distribution, with a lower proportion of the initial PD than HD patients living in the South and more in the West. There were no significant differences in cigarette smoking, cancer, coronary artery disease, or chronic obstructive pulmonary disease, but hypertension was more common and diabetes mellitus, congestive heart failure, peripheral vascular disease, cerebrovascular disease, current drug abuse, and inability to ambulate were all less common among those initially starting PD than HD.

Table 1. Initial type of kidney replacement therapy among individuals with new-onset ESRD due to lupus nephritis in the US, 1995–2006*
 HD 9,622 (85.0)PD 1,382 (12.2)PPreemptive kidney transplant, 313 (2.8)P
  • *

    Values are the number (percentage) unless indicated otherwise; t-tests for continuous variables and Fisher's exact test or chi-square tests for categorical variables. All cell sizes under 11 are not shown, according to US Renal Data System policy. ESRD = end-stage renal disease; HD = hemodialysis; PD = peritoneal dialysis; BMI = body mass index.

  • Comparison of PD to HD. Missing data for PD versus HD: albumin, n = 2,639; hemoglobin, n = 1,255; BMI, n = 401; creatinine, n = 169; race, n = 183; medical insurance, n = 153; and region of residence, n = 13.

  • Comparison of preemptive transplantation to any dialysis. Missing data for preemptive transplantation versus any dialysis: albumin, n = 2,700; hemoglobin, n = 1,301; BMI, n = 410; serum creatinine, n = 179; race, n = 183; medical insurance, n = 161; and region of residence, n = 13.

  • §

    Statistically significant.

Incidence year     
 1995–19971,922 (20.0)397 (28.7)< 0.001§41 (13.1)< 0.001§
 1998–20002,411 (25.1)341 (24.7) 73 (23.3) 
 2001–20032,529 (26.3)336 (24.3) 82 (26.2) 
 2004–20062,760 (28.7)308 (22.3) 117 (37.4) 
Age group, years     
 18–292,612 (27.1)307 (22.2)< 0.001§47 (15.0)< 0.001§
 30–392,392 (24.9)395 (28.9) 81 (25.9) 
 40–492,111 (21.9)354 (25.6) 112 (35.8) 
 ≥502,507 (26.1)326 (23.6) 73 (23.3) 
Serum albumin, mg/dl     
 ≤2.52,618 (27.2)160 (11.6)< 0.001§< 0.001§
 2.6–3.22,430 (25.3)277 (20.0) 29 (9.3) 
 ≥3.32,251 (23.4)629 (45.5) 218 (69.7) 
Hemoglobin, mg/dl     
 ≤8.53,024 (31.4)296 (21.4)< 0.001§16 (5.1)< 0.001§
 8.6–10.02,883 (30.0)376 (27.2)  
 ≥10.12,644 (27.5)526 (38.1) 188 (60.1) 
Serum creatinine, mg/dl     
 ≤6.03,142 (32.7)415 (30.0)0.001§186 (59.4)< 0.001§
 6.1–8.43,035 (31.5)501 (36.3) 84 (26.8) 
 ≥8.53,304 (34.3)438 (31.7) 33 (10.5) 
BMI, kg/m2     
 Underweight, <18.5987 (10.3)163 (11.8)< 0.001§25 (8.0)0.294
 Normal weight, 18.5–254,058 (43.2)563 (40.7) 145 (46.3) 
 Overweight/obese, >254,257 (44.2)575 (41.6) 134 (42.8) 
Sex     
 Female7,822 (81.3)1,183 (85.6)< 0.001§251 (80.2)0.458
 Male1,800 (18.7)199 (14.4) 62 (19.8) 
Race     
 White4,000 (41.6)699 (50.6)< 0.001§251 (80.2)< 0.001§
 African American4,894 (50.9)554 (40.1) 41 (13.1) 
 Asian467 (4.9)97 (7.0) 17 (5.4) 
 American Indian95 (1.0)15 (1.1)  
Ethnicity     
 Hispanic1,567 (16.3)240 (17.4)0.31137 (11.8)0.030§
 Non-Hispanic8,055 (83.7)1,142 (82.6) 276 (88.2) 
Medical insurance     
 Private3,640 (37.8)703 (50.9)0.001§221 (70.6)< 0.001§
 Medicaid2,311 (24.0)199 (14.4) 18 (5.8) 
 Medicare2,512 (26.1)342 (24.8) 59 (18.9) 
 No insurance1,035 (10.8)109 (7.9)  
Employment at ESRD onset     
 Employed1,912 (19.9)448 (32.4)< 0.001§152 (48.6)< 0.001§
 Unemployed7,710 (80.1)934 (67.6) 161 (51.4) 
Region of residence     
 Northeast1,571 (16.3)231 (16.7)0.004§66 (21.1)< 0.001§
 Midwest1,789 (18.6)256 (18.5) 87 (27.8) 
 South4,262 (44.3)558 (40.4) 76 (24.3) 
 West1,899 (19.7)312 (25.6) 83 (26.5) 
 Puerto Rico and US Islands89 (0.9)24 (1.7)  
Cigarette smoking     
 Current smoking380 (4.0)57 (4.1)0.7550.065
 Not smoking9,242 (96.1)1,325 (95.9) 307 (98.1) 
Diabetes mellitus     
 No8,891 (92.4)1,303 (94.3)0.012§305 (97.4)0.001§
 Yes731 (7.6)79 (5.7) 8 (2.6) 
Hypertension     
 No2,528 (25.2)299 (21.6)0.004§88 (28.1)0.179
 Yes7,194 (74.8)1,083 (78.4) 225 (71.9) 
Coronary artery disease     
 No9,054 (94.1)1,304 (94.4)0.702303 (96.8)0.046§
 Yes568 (5.9)78 (5.6)  
Congestive heart failure     
 No8,012 (83.3)1,258 (91.0)< 0.001§307 (98.1)< 0.001§
 Yes1,610 (16.7)124 (9.0)  
Chronic obstructive pulmonary disease     
 No9,394 (97.6)1,360 (98.4)0.070312 (99.7)0.021§
 Yes228 (2.4)22 (1.6)  
Peripheral vascular disease     
 No9,280 (96.5)1,357 (98.2)< 0.001§308 (98.4)0.089
 Yes342 (3.6)25 (1.8)  
Cerebrovascular disease     
 No9,109 (94.7)1,333 (96.5)0.005§301 (96.2)0.311
 Yes513 (5.3)49 (3.6) 12 (3.8) 
Cancer     
 No9,479 (98.5)1,358 (98.2)0.476311 (99.4)0.206
 Yes143 (1.5)24 (1.7)  
Current drug abuse     
 No9,543 (99.2)1,380 (99.9)0.006§313 (100.0)0.128
 Yes79 (0.8)  
Inability to ambulate     
 No9,397 (97.7)1,372 (99.3)< 0.001§313 (100.0)0.009§
 Yes225 (2.3)  
Inability to transfer from bed     
 No9,536 (99.1)1,376 (99.6)0.079313 (100.0)0.104
 Yes86 (0.9)  

In age-adjusted analyses, the likelihood of receiving initial PD (versus HD) was significantly higher in earlier calendar years, for those with higher serum albumin and hemoglobin levels, for women compared to men, for whites compared to African Americans, for those with private compared to any other type of insurance, and for those who were employed compared to those who were unemployed (Table 2). Hispanic ethnicity was not associated with receiving PD versus HD, and there was no strong geographic variation except for increased PD use in Puerto Rico and the US Islands. While cigarette smoking and BMI were not associated with the likelihood of receiving initial PD, comorbidity with diabetes mellitus, congestive heart failure, peripheral vascular disease, cerebrovascular disease, and the inability to ambulate decreased the likelihood of PD, and having hypertension increased it.

Table 2. Age-adjusted and multivariable-adjusted ORs for receiving initial peritoneal dialysis (versus hemodialysis) at lupus nephritis ESRD onset*
 Age-adjusted OR (95% CI)PMultivariable-adjusted OR (95% CI)P
  • *

    OR = odds ratio; ESRD = end-stage renal disease; 95% CI = 95% profile likelihood confidence interval; BMI = body mass index.

  • Adjusting for all variables listed in table.

  • Wald chi-square test for multivariable model.

  • §

    Statistically significant.

  • Age alone in age-adjusted model.

Calendar year, per year increase0.94 (0.92–0.95)< 0.001§0.93 (0.91–0.95)< 0.001§
Age group, years    
 18–290.71 (0.61–0.84)< 0.001§0.84 (0.71–0.99)0.047§
 30–391.0 (ref.) 1.0 (ref.) 
 40–491.02 (0.87–1.19)0.8460.93 (0.79–1.1)0.414
 ≥500.79 (0.67–0.92)0.003§0.73 (0.61–0.87)< 0.001§
Serum albumin, mg/dl    
 ≤2.50.53 (0.44–0.65)< 0.001§0.57 (0.47–0.71)< 0.001§
 2.6–3.21.0 (ref.) 1.0 (ref.) 
 ≥3.32.44 (2.09–2.84)< 0.001§2.14 (1.83–2.50)< 0.001§
Hemoglobin, mg/dl    
 ≤8.50.75 (0.66–0.88)< 0.001§0.79 (0.67–0.94)0.007§
 8.6–10.01.0 (ref.) 1.0 (ref.) 
 ≥10.11.31 (1.09–1.59)< 0.001§1.41 (1.21–1.63)< 0.001§
Serum creatinine, mg/dl    
 ≤6.00.81 (0.71–0.93)0.003§0.98 (0.84–1.13)0.757
 6.1–8.41.0 (ref.) 1.0 (ref.) 
 ≥8.50.80 (0.70–0.92)0.001§0.79 (0.68–0.91)0.001§
BMI, kg/m2    
 Underweight, <18.51.19 (0.99–1.44)0.0681.15 (0.95–1.41)0.160
 Normal weight, 18.5–251.0 (ref.) 1.0 (ref.) 
 Overweight/obese, >250.97 (0.85–1.09)0.5810.98 (0.86–1.12)0.811
Sex    
 Female1.0 (ref.) 1.0 (ref.) 
 Male0.74 (0.63–0.86)< 0.001§0.68 (0.58–0.81)< 0.001§
Race    
 White1.0 (ref.) 1.0 (ref.) 
 African American0.63 (0.56–0.71)< 0.001§0.75 (0.65–0.87)< 0.001§
 Asian1.18 (0.93–1.49)0.1711.18 (0.91–1.54)0.212
 American Indian0.92 (0.53–1.59)0.7551.22 (0.69–2.17)0.496
Ethnicity    
 Non-Hispanic1.0 (ref.) 1.0 (ref.) 
 Hispanic1.10 (0.95–1.28)0.2131.01 (0.83–1.21)0.961
Medical insurance    
 Private1.0 (ref.) 1.0 (ref.) 
 Medicaid0.45 (0.38–0.54)< 0.001§0.61 (0.51–0.73)< 0.001§
 Medicare0.73 (0.64–0.84)< 0.001§0.88 (0.75–1.03)0.102
 No insurance0.55 (0.44–0.68)< 0.001§0.79 (0.63–0.99)0.041§
Region of residence    
 Northeast1.0 (ref.) 1.0 (ref.) 
 Midwest0.98 (0.81–1.18)0.7981.00 (0.82–1.22)0.994
 South0.90 (0.76–1.06)0.1890.98 (0.82–1.17)0.811
 West1.12 (0.93–1.35)0.2170.94 (0.77–1.15)0.551
 Puerto Rico and US Islands1.86 (1.16–2.99)0.010§2.08 (1.24–3.49)0.005§
Employment at ESRD onset    
 Employed1.0 (ref.) 1.0 (ref.) 
 Unemployed0.52 (0.45–0.58)< 0.001§0.64 (0.56–0.74)< 0.001§
Cigarette smoking    
 No1.0 (ref.) 1.0 (ref.) 
 Yes1.02 (0.77–1.36)0.8921.20 (0.89–1.63)0.239
Diabetes mellitus    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.73 (0.58–0.93)0.012§0.95 (0.74–1.22)0.685
Hypertension    
 No1.0 (ref.) 1.0 (ref.) 
 Yes1.22 (1.06–1.39)0.005§1.43 (1.23–1.65)< 0.001§
Coronary artery disease    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.97 (0.76–1.25)0.8181.14 (0.87–1.49)0.344
Congestive heart failure    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.49 (0.40–0.59)< 0.001§0.58 (0.47–0.71)< 0.001§
Chronic obstructive pulmonary disease    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.69 (0.44–1.07)0.0970.77 (0.48–1.23)0.270
Peripheral vascular disease    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.51 (0.34–0.77)0.001§0.64 (0.42–0.98)0.040§
Cerebrovascular disease    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.65 (0.48–0.88)0.005§0.74 (0.54–1.02)0.063
Cancer§    
 No1.0 (ref.) 1.0 (ref.) 
 Yes1.18 (0.76–1.83)0.4621.19 (0.75–1.88)0.461
Current drug abuse    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.17 (0.04–0.68)0.013§0.33 (0.08–1.35)0.123
Inability to ambulate    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.30 (0.16–0.58)< 0.001§0.40 (0.18–0.91)0.030§
Inability to transfer from bed    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.50 (0.22–1.14)0.0971.63 (0.54–4.89)0.385

Many of these associations continued to be observed even after multivariable adjustment (Table 2). Age at ESRD onset of <50 years, earlier calendar year during the period of study, female sex, white race compared to African American race, having private medical insurance versus Medicaid, and being employed were all independently associated with significantly higher odds of receiving PD compared to HD. Higher serum albumin and serum hemoglobin levels at ESRD onset were also associated with the increased odds of receiving initial PD, as was the presence of hypertension. Comorbidity with congestive heart failure, peripheral vascular disease, and the inability to ambulate were associated with a decreased likelihood of PD. We did not detect interactions between race and US region in determining the risk of receiving initial PD.

Only 313 individuals received a preemptive kidney transplant without preceding dialysis (Table 1), but the proportion grew over successive calendar years (from 1.7% to 3.7%). The age distribution of the preemptive transplant patients was more concentrated between ages 30–50 years than that of the dialysis patients. These patients also had significantly higher serum albumin and hemoglobin levels and lower serum creatinine levels at USRDS enrollment. While their BMI and sex distributions were similar to those of the dialysis patients, the proportions of African Americans and Hispanics, those with Medicaid or no health insurance, those unemployed, and those living in the US South were much lower than for dialysis patients. The proportions of patients with diabetes mellitus, coronary artery disease, congestive heart failure, chronic obstructive pulmonary disease, and the inability to ambulate were significantly lower among those undergoing preemptive kidney transplantation versus dialysis.

Age-adjusted analyses of receiving a preemptive kidney transplant (versus any dialysis) at ESRD onset are shown in Table 3. The odds of receiving a preemptive transplant were highest among those with serum albumin >3.2 mg/dl, hemoglobin >10.0 mg/dl, and creatinine <6.0 mg/dl. Males and females were equally likely to receive transplants, but the odds of receiving a transplant were significantly lower among both African Americans and Asians compared to whites. Age-adjusted odds of a preemptive transplant were significantly lower for those with nonprivate health insurance and for those who were unemployed. A significant regional variation in the odds of receiving a preemptive kidney transplant was observed, with the lowest odds found in the Southern states.

Table 3. Age-adjusted and multivariable-adjusted ORs for receiving preemptive kidney transplantation (versus dialysis) at lupus nephritis ESRD onset*
 Age-adjusted OR (95% CI)PMultivariable-adjusted OR (95% CI)P
  • *

    OR = odds ratio; ESRD = end-stage renal disease; 95% CI = 95% profile likelihood confidence interval; BMI = body mass index.

  • Adjusting for all variables listed in table.

  • Wald chi-square test for multivariable model.

  • §

    Statistically significant.

  • Age alone in age-adjusted model.

Calendar year, per year increase1.08 (1.05–1.12)< 0.001§1.04 (1.00–1.08)0.063
Age group, years    
 18–290.55 (0.39–0.80)< 0.001§0.76 (0.51–1.12)0.164
 30–391.0 (ref.) 1.0 (ref.) 
 40–491.56 (1.17–2.09)0.003§1.08 (0.77–1.49)0.667
 ≥500.89 (0.64–1.22)0.4620.61 (0.42–0.89)0.010§
Serum albumin, mg/dl    
 ≤2.50.17 (0.07–0.45)< 0.001§0.17 (0.07–0.45)< 0.001§
 2.6–3.21.0 (ref.) 1.0 (ref.) 
 ≥3.36.88 (4.65–10.17)< 0.001§4.66 (3.09–7.03)< 0.001§
Hemoglobin, mg/dl    
 ≤8.50.25 (0.15–0.44)< 0.001§0.40 (0.22–0.70)0.001§
 8.6–10.01.0 (ref.) 1.0 (ref.) 
 ≥10.13.03 (2.27–4.05)< 0.001§1.76 (1.28–2.41)< 0.001§
Serum creatinine, mg/dl    
 ≤6.02.26 (1.74–2.94)< 0.001§2.51 (1.87–3.37)< 0.001§
 6.1–8.41.0 (ref.) 1.0 (ref.) 
 ≥8.50.37 (0.25–0.55)< 0.001§0.46 (0.30–0.71)< 0.001§
BMI, kg/m2    
 Underweight, <18.50.68 (0.45–1.05)0.0830.92 (0.57–1.47)0.726
 Normal weight, 18.5–251.0 (ref.) 1.0 (ref.) 
 Overweight/obese, >250.86 (0.68–1.09)0.2130.94 (0.72–1.23)0.655
Sex    
 Female1.0 (ref.) 1.0 (ref.) 
 Male1.13 (0.86–1.51)0.3841.07 (0.78–1.47)0.684
Race    
 White1.0 (ref.) 1.0 (ref.) 
 African American0.14 (0.10–0.19)< 0.001§0.21 (0.15–0.31)< 0.001§
 Asian0.57 (0.35–0.95)0.031§0.44 (0.26–0.77)0.004§
 American Indian0.72 (0.26–1.98)0.5240.69 (0.22–2.14)0.518
Ethnicity    
 Non-Hispanic1.0 (ref.) 1.0 (ref.) 
 Hispanic0.73 (0.52–1.04)0.0780.51 (0.34–0.76)0.001§
Medical insurance    
 Private1.0 (ref.) 1.0 (ref.) 
 Medicaid0.16 (0.10–0.25)< 0.001§0.35 (0.21–0.60)< 0.001§
 Medicare0.42 (0.31–0.56)< 0.001§0.56 (0.40–0.78)< 0.001§
 No insurance0.13 (0.06–0.28)< 0.001§0.28 (0.13–0.62)0.002§
Employment at onset ESRD    
 Employed1.0 (ref.) 1.0 (ref.) 
 Unemployed0.28 (0.22–0.35)< 0.001§0.57 (0.43–0.75)< 0.001§
Region of residence    
 Northeast1.0 (ref.) 1.0 (ref.) 
 Midwest1.16 (0.84–1.61)0.3651.09 (0.75–1.58)0.656
 South0.44 (0.32–0.62)< 0.001§0.62 (0.43–0.91)0.013§
 West1.04 (0.75–1.45)0.8030.79 (0.54–1.15)0.209
 Puerto Rico and US Islands0.25 (0.03–1.81)0.1700.57 (0.07–4.42)0.590
Cigarette smoking    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.44 (0.19–0.99)0.046§0.62 (0.26–1.47)0.277
Diabetes mellitus    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.31 (0.15–0.62)0.001§0.57 (0.27–1.19)0.134
Hypertension    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.82 (0.64–1.06)0.1230.97 (0.73–1.29)0.817
Coronary artery disease    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.49 (0.26–0.93)0.030§0.53 (0.27–1.05)0.070
Congestive heart failure    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.10 (0.05–0.23)< 0.001§0.20 (0.09–0.46)< 0.001§
Chronic obstructive pulmonary disease    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.13 (0.02–0.95)0.045§0.22 (0.03–1.64)0.140
Peripheral vascular disease    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.46 (0.19–1.13)0.0890.85 (0.32–2.23)0.737
Cerebrovascular disease    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.72 (0.40–1.29)0.2730.94 (0.50–1.76)0.846
Cancer    
 No1.0 (ref.) 1.0 (ref.) 
 Yes0.38 (0.09–1.55)0.1790.29 (0.07–1.22)0.091

In age-adjusted models, those who had diabetes mellitus, coronary artery disease, congestive heart failure, and chronic obstructive pulmonary disease had decreased odds of receiving a preemptive kidney transplant. BMI and hypertension were not significant predictors of receiving a preemptive kidney transplant and were not included in the final multivariable models. Current drug abuse, the inability to ambulate, or the inability to transfer to bed were not included as covariables in the age-adjusted or multivariable models as too few subjects had these comorbidities.

After multivariable adjustment, those ages >50 years and Hispanics had significantly reduced odds of receiving preemptive kidney transplants. Comorbidity with diabetes mellitus, cigarette smoking, and coronary artery disease was no longer significantly associated with odds of transplant. The significant predictors of receiving a preemptive transplant compared to HD were identical to those of receiving a preemptive transplant compared to any dialysis with very similar levels of significance (data not shown). We did not detect significant interactions between race and region in determining the odds of receiving a preemptive kidney transplant.

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Employing nationwide data from 1995–2006, we have found substantial sociodemographic variation in the choice of initial kidney replacement therapy for incident LN ESRD patients. Only a small minority of patients, less than 3% overall, proceeded directly to kidney transplantation without first receiving some form of dialysis. HD was the predominant initial dialysis modality throughout this period and its usage has grown over time. PD was used more commonly among female patients, whites versus African Americans, those with private insurance versus Medicaid, and those who were employed. Patients who received PD appeared to be in significantly better general health than those who received HD, with higher serum levels of hemoglobin and albumin at ESRD onset. The presence of hypertension at ESRD onset was significantly associated with increased odds of receiving initial PD. Hypertension has been associated with better outcomes among ESRD patients in past studies, and lower blood pressure may be an indicator of frailty and poor nutritional status in this population (18). Additionally, it may be that hypertension was more reliably coded by physicians who are apt to start patients on PD. The small group of patients who underwent preemptive kidney transplantation at ESRD onset was even more highly selected. Compared to dialysis patients, they were significantly younger, with better laboratory values, significantly more of them were white and non-Hispanic, fewer lived in the US South, more were employed, and more had private medical insurance.

HD and PD have distinct advantages and disadvantages. PD is a more flexible option with less disruption required during peak work hours (19). After adjusting for ethnicity, age, distance from treatment center, treatment length, and employment status, studies of patient quality of life have found PD patients to be more satisfied and happier than their otherwise similar HD counterparts (20, 21). In a large survey of practicing nephrologists, it was felt by the majority that both PD and home HD were underutilized, and respondent physicians felt that 26–39% of ESRD patients could be successfully placed on PD (22). There is also a clear economic advantage to PD compared to HD. According to USRDS annual data reporting, Medicare spends approximately $18,000 less annually for a PD patient than for a HD patient (23). However, the large degree of patient autonomy required entails good patient-provider communication and adherence with home PD regimens and ESRD medications.

Previous studies comparing PD versus HD mortality among all-cause ESRD patients are inconclusive. Several studies have suggested early survival advantages in PD versus HD patient populations within the first 1–2 years of ESRD onset, although with similar long-term survival rates (24, 25). Other research has shown significantly higher death rates in PD versus HD patients soon after dialysis initiation, especially in elderly diabetics (26). Several prior small studies have suggested an increased risk of peritonitis and other infectious complications among immunosuppressed LN ESRD patients receiving PD. In 1996, Andrews and colleagues reported that immunosuppressed patients undergoing PD had 3 times as many hospitalizations and more than double the number of peritonitis episodes as nonimmunosuppressed PD patients (27). Subsequently, in a small study involving 23 LN ESRD patients undergoing PD compared to non-LN PD controls, Huang and colleagues reported a much higher rate of peritonitis and overall mortality among the LN patients, in particular in association with corticosteroid use (7). A 2005 study reported higher rates of peritonitis, non–catheter-related infections, and mortality among a small group of LN PD patients compared to nondiabetic, non-LN PD patients (10). While the current study elucidates important clinical determinants and sociodemographic patterns among LN patients choosing HD or PD, we cannot comment on the safety or efficacy of these dialysis modalities, and further study of the comparative effectiveness of these therapies for LN ESRD is warranted.

The effects of dialysis modality upon SLE disease activity, morbidity, and mortality are not known; existing observational data comparing outcomes are sparse, conflicting, and difficult to interpret as a healthier, more advantaged patient population may be selected for PD (7–13). One small study reported a higher increase from baseline in SLE activity scores in patients undergoing PD compared to HD, but no differences in survival rates (28). Pretransplant use of PD compared with HD has been associated with better allograft survival among LN ESRD transplant recipients (29) and lower risk of developing posttransplant bacteremia (30).

Lupus patients with recurrent infections, malignancies, or other preexisting comorbidities may be poor candidates for PD or preemptive transplantation due to increased complication rates (7, 9, 10). A recent survival analysis of LN ESRD undergoing PD revealed that predialysis SLE activity scores had limited prognostic value but that preexisting comorbidities, especially cardiovascular conditions, were associated with significantly higher mortality rates among SLE PD patients (9). For the current study, data were not available concerning prior infections, and we were not able to calculate complete Charlson comorbidity scores. We did find that comorbidities including diabetes mellitus, congestive heart failure, chronic obstructive pulmonary disease, peripheral vascular disease, and the inability to ambulate were associated with decreased odds of receiving either PD or preemptive kidney transplant.

Limited geographic access to PD services and a national transition to predominant care provision by chain-affiliated dialysis facilities are likely responsible for increasing the proportion of all US ESRD patients started on HD in the past 2 decades (19, 23). From 1995 to 1999, the proportion of dialysis facilities in the US offering PD services was 56%, which declined to 47% by 2003 (31). In a large cohort study, PD availability was greater in metropolitan cities and the Northeast but more limited in the South, Midwest, and rural areas (20). PD access was also more limited in hospital referral regions with higher proportions of African American, Asian, and Hispanic ESRD patients. Survey data suggest that recent nephrology fellows have markedly less familiarity, exposure, and training with PD compared to HD, which likely influences how they will counsel patients concerning dialysis options (19, 25). Understanding the sociodemographic predictors of initial dialysis modality among LN ESRD patients is increasingly relevant since the CMS ESRD 2011 Prospective Payment System Program has recently replaced the current adjusted composite payment system, thereby effectively providing strong incentives to increase utilization of home dialysis modalities, including PD (32–36).

While the number of preemptive kidney transplantations performed for LN ESRD has gradually increased, there are still few performed annually and recipients remain younger, predominantly white, and overall healthier patients with private medical insurance. SLE disease activity and risk of recurrence may be one clinically important reason to postpone kidney transplantation. A traditional recommendation has been for LN patients to undergo at least 3–6 months of dialysis prior to renal transplantation with the goal of ensuring quiescent lupus (37). In recent national data, the highest risks of recurrent LN after kidney transplantation were among African-Americans, women, and patients younger than age 33 years (17). However, the absolute risks were low and the prevalence of recurrent nephritis after transplant for all LN ESRD patients was only 2.44% from 1987–2006. The increasing rate of preemptive kidney transplantation suggests that clinical practice may be changing with respect to the requirement of a period of time on dialysis to allow disease activity to subside before transplantation. While we have data on some clinical parameters at ESRD onset, no data concerning SLE disease duration, activity, or organ damage are available for these patients and this is recognized as a limitation in our study.

Geographic access to transplant organs likely affects preemptive kidney transplantation rates. Lower rates of wait-listing for and receipt of kidney transplants among all-cause ESRD patients in the US South have been demonstrated in past studies (38). We found significant regional variation in the odds of receiving a preemptive kidney transplant for LN ESRD, with substantially lower likelihood in the US South. In addition to regional differences, discrepancies in ESRD dialysis management and transplant referral practices exist among academic medical centers, community hospitals, and private clinic settings. Patients living in rural areas with less access to academic centers have lower rates of kidney transplant wait-listing and transplantation (39). Nephrology referrals tend to be delayed in rural areas where patients are being managed in smaller clinics and community hospitals. Late specialist referrals have been associated with tardy dialysis initiation, increased morbidity, worse long-term survival rates, and reduced rates of kidney transplantation among ESRD patients (26, 40, 41). Unfortunately, the type of referring center, academic, or community hospital is not specified in the USRDS.

Another limitation of this study is the use of data reported by the attending nephrologist and staff on the USRDS Medical Evidence Report at the onset of ESRD for many baseline variables. Consistent completion of this form is expected as it is a US government document establishing the onset of ESRD and qualification for Medicare insurance coverage, but missing data do exist for some of the baseline characteristics and some underreporting of comorbidities is known to occur (42). The validity of the USRDS CMS Medical Evidence Report for the diagnoses of glomerulonephritis has recently been studied in a subpopulation of patients with renal biopsy results enrolled in the Glomerular Disease Collaborative Network (43). The positive predictive value of a diagnosis of SLE was perfect (100%) and the false-positive rate was therefore zero. However, the sensitivity of this diagnosis was low, i.e., only 27%, and many patients that were documented as having more general glomerulonephritis were found to have LN on their renal biopsies. This implies that the cases included here do have true LN, although a substantial number of other cases were not included. Agreement between the form and biopsy results improved substantially after 1995, when the form was revised (43), and only cases since 1995 were included in our analyses. Additionally, in the Glomerular Diseases Collaborative Network population, agreement for individual disease diagnoses did not differ by sex, race, location of the nephrologist, or whether the biopsy was performed before or after the form was completed (43), suggesting that the population of LN ESRD patients not included in our study is similar to that included.

In addition to SLE disease activity, which may vary by race, ethnicity, age and sex, other preexisting comorbidities, financial, and social circumstances are considered by patients and their providers in selecting the most suitable initial dialysis option. Our study was unable to account for cultural beliefs, educational background, and language barriers. These factors have been shown to influence decision making concerning dialysis management and kidney transplantation (44–46). The USRDS unfortunately also does not include data on marital status or other social support.

There are no other large observational studies of initial kidney replacement therapy type among patients with ESRD due to LN. Moroni and colleagues have observed that in their own clinical practice the initial selection of PD versus HD tended to be more common for younger, healthier, and ambulatory LN ESRD patients (8, 47), and we have confirmed this in a much larger national cohort from a different country. We found that after adjustment for clinical and sociodemographic variables, African American compared to white race was associated with a 25% reduction in the odds of receiving initial PD compared to HD and a 79% reduction in the odds of receiving a preemptive kidney transplant. Exactly how complex decisions about kidney replacement therapy are made for and with LN ESRD patients is not known. Lupus disease severity likely differs among racial and ethnic groups, potentially influencing both the incidence of ESRD, choices of kidney replacement therapy, referral for transplantation (48), and ultimately outcomes from LN ESRD. Rheumatologists and primary care physicians may be unaware of the factors involved in the decision-making process, and providers may make unfounded assumptions about patients' attitudes, preferences, or adherence to care (49).

The current study provides data about the enormous sociodemographic variation that exists in the selection of kidney replacement modalities for LN ESRD patients in the US. The next step will be to evaluate the appropriateness of this variation and the comparative effectiveness of these therapies for LN ESRD patients. In future analyses, we intend to pursue these important and related avenues of research.

AUTHOR CONTRIBUTIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be submitted for publication. Dr. Costenbader had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study conception and design. Devlin, Waikar, Solomon, Lu, Shaykevich, Alarcón, Winkelmayer, Costenbader.

Acquisition of data. Devlin, Waikar, Solomon, Lu, Shaykevich, Alarcón, Winkelmayer, Costenbader.

Analysis and interpretation of data. Devlin, Waikar, Solomon, Lu, Shaykevich, Alarcón, Winkelmayer, Costenbader.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES
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