Mycobacterium tuberculosis infection incidence in hospitalized renal transplant patients in the United States, 1998-2000

The incidence, risk factors, and prognosis for Mycobacterium tuberculosis (MTB) infection have not been reported in a national population of renal transplant recipients. We performed a retrospective cohort study of 15,870 Medicare patients who received renal transplants from January 1, 1998 to July 31, 2000. Cox regression analysis derived adjusted hazard ratios (AHR) for factors associated with a diagnosis of MTB infection (by Medicare Institutional Claims) and the association of MTB infection with survival. There were 66 renal transplant recipients diagnosed with tuberculosis infection after transplant (2.5 cases per 1000 person years at risk, with some falling off of cases over time). The most common diagnosis was pulmonary TB (41 cases). In Cox regression analysis, only systemic lupus erythematosus (SLE) was independently associated with TB. Mortality after TB was diagnosed was 23% at 1 year, which was significantly higher than in renal transplant recipients without TB (AHR, 4.13, 95% CI, 2.21, 7.71, p < 0.001). Although uncommon, MTB infection is associated with a substantially increased risk of mortality after renal transplantation. High-risk groups, particularly those with SLE prior to transplant, might benefit from intensified screening.

Thrombotic microangiopathy after renal transplantation in the United States

BACKGROUND

Analysis of the incidence, time to event, and risk factors for thrombotic microangiopathy (TMA) after renal transplantation (RT), has not been reported in a national population.

METHODS

This is a historical cohort study of 15,870 RT recipients in the United States Renal Data System (USRDS) with Medicare as their primary payer between January 1, 1998, and July 31, 2000, followed until December 31, 2000. Patients with Medicare claims with a diagnosis of TMA (International Classification of Diseases, 9th Revision, codes 283.11x or 446.6x) after RT were assessed by Cox regression.

RESULTS

Among patients with end-stage renal disease owing to hemolytic uremic syndrome (HUS), 29.2% later had TMA versus 0.8% of patients with ESRD owing to other causes. The incidence of TMA in RT recipients was 5.6 episodes per 1,000 person-years (PY; 189/1,000 PY; for recurrent TMA versus 4.9/1,000 PY for de novo TMA). The risk of TMA was highest for the first 3 months after transplant. Risk factors for de novo TMA included younger recipient age, older donor age, female recipient, and initial use of sirolimus. Patient survival rate after TMA was approximately 50% at 3 years.

CONCLUSION

De novo TMA is uncommon and may occur later after RT than previously reported. Risk factors for de novo TMA were also identified.

Outcomes associated with recipient and donor hepatitis C serology status after kidney transplantation in the United States: analysis of the USRDS/UNOS database

Analysis of the USRDS kidney transplant registry disclosed that use of hepatitis C virus-positive donor (DHCV+) kidneys was an independent risk factor for patient death after kidney transplantation when compared to use of DHCV- kidneys, and that death in recipients of DCHV+ kidneys occurred earlier than previously reported. This increased risk of death was delayed for about 2 years, suggesting the development of an intermediate complication that resulted in a later increased risk of death. While liver disease early after transplant in these patients was rare, new-onset diabetes mellitus occurred early and commonly, suggesting this complication as a prominent mediator of mortality associated with transplantation with DHCV+ kidneys. Identification of new-onset diabetes mellitus may represent a new target of opportunity to improve outcomes associated with use of DHCV+ kidneys. Even under the current circumstances, use of DHCV+ kidneys was also independently associated with a survival experience that, although less favorable than associated with transplantation of DHCV- kidneys, was significantly better than remaining on the kidney transplant waiting list. Whether this survival advantage applies to all relevant subgroups could not be assessed and warrants further study. Our analyses suggest opportunities to improve survival and reduce morbidity after use of DHCV+ kidneys.

Arteriovenous fistula use and heart disease in long-term elderly hemodialysis patients: analysis of United States Renal Data System Dialysis Morbidity and Mortality Wave II

BACKGROUND

There are some concerns that arteriovenous fistula (AVF) use or other dialysis specific factors may exacerbate cardiovascular disease in long-term hemodialysis (HD) patients.

METHODS

We performed a historical cohort study of the United States Renal Data System Dialysis Morbidity and Mortality Wave II study, limited to 993 patients who started HD in 1996 with valid information on vascular access and who were primarily eligible for Medicare at the start of the study. We assessed the association between hemodialysis vascular access and heart disease, defined as Medicare Claims for heart failure (HF, International Classification of Diseases (ICD9) code 428.x) and acute coronary syndromes (ACS, ICD9 code 410.x and 411.x). Cox proportional hazards regression (using propensity analysis) was used to model adjusted hazard ratios (AHR) for the association between patients factors and heart disease after dialysis.

RESULTS

The rate of HF per 100 person years at risk (PYAR) was 19.6 among AVF users, 25.7 among patients using polytetrafluoroethylene grafts (grafts), and 31.1 among patients using temporary catheters. Corresponding rates of ACS were 8.2 among AVF users, 11.0 among users of grafts, and 12.4 among users of temporary catheters. In Cox Regression analysis, there was no significant association between AVF use and either HF or ACS. This lack of association was consistent across gender, diabetes, race, and age.

CONCLUSIONS

We found that AVF use had no significant association with the incidence of HF or ACS. We conclude that use of AVF by 60 days after the start of dialysis is not associated with an increased risk of later non-fatal cardiovascular outcomes in long-term hemodialysis patients.

Meeting the challenge to improve the treatment of hypertension in blacks

Hypertension is more prevalent and severe in African descendent populations living outside Africa than in any other population. Given this greater burden of hypertension in blacks, it is increasingly necessary to refine strategies to prevent the disorder as well as improve its treatment and control. This review assesses results from clinical trials on lifestyle and pharmacologic interventions to identify which approaches most effectively prevent adverse hypertension-related outcomes in African descendent populations. The Dietary Approaches to Stop Hypertension (DASH) study provided evidence that a carefully controlled diet rich in fruits, vegetables, low-fat dairy foods, and reduced in saturated fat, total fat, and cholesterol (i.e., the DASH diet) reduces blood pressure in blacks and is well accepted. The combination of the DASH diet with reduction in dietary sodium below 100 mmol/d may provide a reduction in blood pressure beyond that reached by the DASH diet alone. Physical exercise and interventions to reduce psychological stress may also reduce blood pressure in blacks. Strong evidence from numerous studies is a compelling argument for continuing to recommend diuretics and beta blockers as first-line antihypertensive therapy for persons of all races. Some new studies also favor angiotensin-converting enzyme inhibitors as first-line antihypertensive drugs. The African American Study of Kidney Disease and Hypertension provided evidence that an angiotensin-converting enzyme inhibitor-based treatment program is more beneficial than calcium channel blockers and beta blockers in reducing the progression of renal failure in blacks with hypertensive nephropathy. Studies in patients with diabetes have also shown evidence that both angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists are more effective than other classes of antihypertensives in reducing adverse renal events. Studies to evaluate the effects of the new antihypertensives in improving outcomes in blacks living outside the United States are needed.

HIVAN and medication use in chronic dialysis patients in the United States: analysis of the USRDS DMMS Wave 2 study

BACKGROUND

The use and possible effects of factors known to improve outcomes in patients with human immunodeficiency virus associated nephropathy (HIVAN), namely of angiotensin converting enzyme inhibitors (ACE) and antiretroviral therapy, has not been reported for a national sample of dialysis patients.

METHODS

We conducted a historical cohort study of the United States Renal Data System (USRDS) Dialysis Morbidity and Mortality Study (DMMS) Wave 2 to identify risk factors associated with increased mortality in these patients. Data were available for 3374 patients who started dialysis and were followed until March 2000. Cox Regression analysis was used to model adjusted hazard ratios (AHR) with HIVAN as a cause of end stage renal disease (ESRD) and its impact on mortality during the study period, adjusted for potential confounders.

RESULTS

Of the 3374 patients who started dialysis, 36 (1.1%) had ESRD as a result of HIVAN. Only 22 (61%) of patients with HIVAN received antiretroviral agents, and only nine patients (25%) received combination antiretroviral therapy, and only 14% received ACE inhibitors. Neither the use of multiple antiretroviral drugs (AHR, 0.62, 95% CI, 0.10, 3.86, p = 0.60), or ACE inhibitors were associated with a survival advantage. Patients with HIVAN had an increased risk of mortality (adjusted hazard ratio, 4.74, 95% Confidence Interval, 3.12, 7.32, p < 0.01) compared to patients with other causes of ESRD.

CONCLUSIONS

Medications known to improve outcomes in HIV infected patients were underutilized in patients with HIVAN. Adjusted for other factors, a primary diagnosis of HIVAN was associated with increased mortality compared with other causes of ESRD.

Renal cell carcinoma as a cause of end-stage renal disease in the United States: patient characteristics and survival

BACKGROUND

The patient characteristics and mortality associated with renal cell carcinoma (RCC) as a cause of end-stage renal disease (ESRD) have not been characterized for a national population.

METHODS

An historical cohort study of renal cell carcinoma (RCC) was conducted from April 1, 1995, to December 31, 1999. Included were 360,651 patients in the United States Renal Data System (USRDS) who were initiated on ESRD therapy with valid causes of ESRD.

RESULTS

Of the study population, 1646 patients (0.5%) had RCC. The mean age of patients with RCC was 66.8 +/- 14.6 years versus 61.3 +/- 16.4 years for patients with other causes of ESRD (P < 0.01 by Student t test). The unadjusted 3-year survival (censored at the date of renal transplantation) of patients with RCC during the study period was 23% versus 36% in all other patients [adjusted hazard ratio (AHR), 1.10, 95% confidence interval (CI) 1.02-1.19, P = 0.019 by Cox regression]. However, patients with RCC who underwent nephrectomy (bilateral or unilateral) had significantly better survival compared to RCC patients who did not (AHR, 0.73, 95% CI, 0.63-0.85, P < 0.01), and their survival was not significantly different in comparison with nondiabetic ESRD patients. Bilateral nephrectomy (vs. unilateral) was not associated with any difference in adjusted mortality.

CONCLUSION

Among patients with ESRD, the demographics of those with RCC were similar to those of patients with RCC in the general population. Overall, patients with RCC had decreased survival compared to patients with other causes of ESRD; those who underwent nephrectomy had significantly better survival than those who did not, with survival comparable to patients with nondiabetic ESRD.

The rationale and design of the AASK cohort study

Hypertensive kidney disease commonly progresses. The primary objective of the AASK (African American Study of Kidney Disease and Hypertension) Cohort Study is to determine prospectively the course of kidney function and risk factors for kidney disease progression in African Americans with hypertensive kidney disease who receive recommended anti-hypertensive therapy. The AASK Cohort Study is a prospective, observational study that is an extension of the AASK trial. The AASK trial tested the effects of three medications used as initial anti-hypertensive therapy (ramipril, metoprolol, and amlodipine) and two levels of BP control. Of the 1094 trial participants, approximately 650 to 700 individuals who have not reached ESRD will likely enroll in the Cohort Study. Risk factors to be studied include environmental, genetic, physiologic, and socioeconomic variables. The primary renal outcome is a composite clinical outcome defined by doubling of serum creatinine, ESRD, or death. Medication treatment for hypertension, beginning with the angiotensin converting enzyme inhibitor ramipril, is offered to all participants. In this fashion, the study directly controls two of the major determinants of kidney disease progression: treatment of hypertension and use of renoprotective, anti-hypertensive medication. The minimum duration of follow-up in the Cohort Study is 5 yr (total of 9 to 12 yr, including the period of the AASK trial). Ultimately, data from the AASK Cohort Study should enhance our understanding of the risk factors and processes that determine the progression of kidney disease. Such results might eventually lead to new strategies that delay or prevent ESRD.

Hospitalized psychoses after renal transplantation in the United States: incidence, risk factors, and prognosis

Although it is recommended that renal transplant (RT) candidates routinely undergo screening for mental health-related conditions, national statistics for psychoses after RT have not been reported. This is a historical cohort study of 39,628 renal transplant recipients in the United States Renal Data System between July 1, 1994, and June 30, 1998, and followed until December 31, 1999. Adjusted hazard ratios (AHR) for time to hospitalization for both a primary and secondary discharge diagnosis of psychoses (ICD-9 codes 290.x-299.x) after RT and mortality/graft loss after psychosis were assessed by Cox Regression. In addition, rates of psychosis were compared with 178,986 patients with Medicare as their primary payer who started chronic dialysis from April 1, 1995, to June 29, 1999. The incidence of psychoses was 7.5/1000 person-years (PY) after RT compared with 7.2/1000 PY for all patients on chronic dialysis and 9.6/1000 PY for dialysis patients aged 65 yr or younger. Among RT recipients, graft loss (AHR, 2.97; 95% CI, 2.19 to 4.02), allograft rejection, and cadaveric donation were independently associated with psychosis, which was associated with an increased risk of both death (AHR, 2.09; 95% CI, 1.71 to 2.56; P < 0.001) and graft loss (AHR, 1.79; 95% CI, 1.15 to 2.78; P = 0.01). Graft loss due to noncompliance was significantly more common after psychosis (9.0% versus 3.7% in patients not hospitalized for psychosis; P < 0.001). The incidence of hospitalized psychosis was not substantially higher after RT compared with chronic dialysis patients. Psychoses were independently associated with increased risk of death and graft loss after renal transplantation, possibly mediated through medical non-adherence.

Heart failure as a cause for hospitalization in chronic dialysis patients

BACKGROUND

Risk factors for heart failure (HF) have not been reported previously in a nationally representative sample of dialysis patients.

METHODS

We conducted a historic cohort study of 1,995 patients enrolled in the US Renal Data System Dialysis Morbidity and Mortality Study Wave 2 who were Medicare eligible at the study start and were followed up until December 31, 1999, or receipt of a renal transplant. Cox regression analysis was used to model associations with time to first hospitalization for both recurrent and de novo HF (International Classification of Diseases, Ninth Revision code 428.x), defined as patients with and without a history of HF, respectively.

RESULTS

The incidence density of HF was 71/1,000 person-years. Angiotensin-converting enzyme inhibitors and beta-blockers were each used in less than 25% of patients with a known history of HF. A history of coronary heart disease was associated with an increased total risk for HF, as were hemodialysis (versus peritoneal dialysis), aspirin use, and a history of diabetes. However, hemodialysis and aspirin use were the only factors associated with both de novo and recurrent HF. Widened pulse pressure was associated with de novo HF. The mortality rate after HF was 83% at 3 years (adjusted hazard ratio for mortality, 2.10; 95% confidence interval, 1.80 to 2.45; P < 0.0001).

CONCLUSION

In chronic dialysis patients, hemodialysis and aspirin use were associated with increased risk for both total and de novo HF. Hospitalized HF was associated with a significantly increased risk for death.

Hospitalized atrial fibrillation after renal transplantation in the United States

Renal transplant recipients have a high incidence of hypertension, a known risk factor for atrial fibrillation (AF), as well as factors that could increase their risk of AF. However, the incidence of, risk factors for, and mortality associated with AF after renal transplantation have not been reported. We present a historical cohort study of 39 628 renal transplant recipients in the United States Renal Data System between 1 July 1994 and 30 June 1998.

DATA SOURCE

USRDS files through May 2000. Associations with hospitalizations for a primary diagnosis of AF (ICD-9 codes 427.31) after renal transplant were assessed by Cox Regression analysis. Tacrolimus was not approved for use by the FDA during the time-frame of the study. The incidence of AF after renal transplantation was 5.8 episodes/1000 person-years. In Cox Regression analysis, recipients who were older age, experienced graft loss, rejection, had higher body mass index, renal failure due to hypertension, and cyclosporine use (vs. tacrolimus use) were associated with increased risk of hospitalized AF. Atrial fibrillation was not uncommon after renal transplantation, and was associated with increased risk of mortality, primarily from cardiovascular disease. The strongest risk factors for AF after renal transplantation were older age, allograft rejection, graft loss and obesity.

Survival by time of day of hemodialysis: analysis of United States Renal Data System Dialysis Morbidity and Mortality Waves III/IV

BACKGROUND

Whether morning shift hemodialysis is associated with improved survival in comparison to patients receiving afternoon shift hemodialysis has not been shown for a representative sample of US chronic hemodialysis patients.

METHODS

We conducted a historical cohort study of a national database (US Renal Data System Dialysis Morbidity and Mortality Waves III/IV) of 6,939 patients who started hemodialysis therapy from January 1, 1990, through December 31, 1993. Patients were followed up through April 9, 2000, and censored at the time of change to a different modality, including transplantation. We estimated the adjusted hazard ratio for all-cause mortality based on the time of day of hemodialysis (0500 to 1200 for morning shift, 1200 to 1800 for afternoon shift, 1800 to midnight for evening shift). Cox regression analysis was used to adjust for other factors associated with survival.

RESULTS

For patients aged 60 years and older, the unadjusted 4-year survival rate for patients on morning shift hemodialysis was 28.8% versus 24.1% for patients on afternoon shift hemodialysis and 38.7% for patients on evening shift hemodialysis (P < 0.01 by log-rank test for both versus afternoon shift hemodialysis). Both morning shift (adjusted hazard ratio, 0.90; 95% confidence interval [CI], 0.83 to 0.98; P = 0.02) and evening shift hemodialysis (adjusted hazard ratio, 0.62; 95% CI, 0.48 to 0.80; P < or = 0.001) were independently associated with a lower risk for mortality compared with afternoon shift hemodialysis. No such differences were seen for patients younger than 60 years. Both morning shift and evening shift hemodialysis were independently associated with improved survival compared with afternoon shift hemodialysis in elderly chronic hemodialysis patients. No such association was found for younger patients.

Hospitalized nephrolithiasis after renal transplantation in the United States

The national incidence of and risk factors for hospitalized nephrolithiasis (NEP) in renal transplant (RT) recipients has not been reported. We conducted a historical cohort study of 42 096 RT recipients in the United States Renal Data System between 1 July 1994 and 30 June 1998. The 1-year incidence of NEP (ICD-9 codes 592.x) after RT in 1997 was compared to the rate of NEP in the general population using the National Hospital Discharge Survey. Associations with time to hospitalizations for a primary diagnosis of nephrolithiasis were assessed by Cox Regression. NEP was uncommon after RT (104 cases per 100 000 person years in 1997). However, females, but not males, had a statistically significant increased risk of NEP compared to the general population (rate ratio for females, 2.84, 95% confidence interval, 2.35-3.58). Kidney stones were more common than ureteral stones, and percutaneous procedures were more common than ureteroscopy or extracorporeal shock wave lithotripsy (ESWL). The only risk factor identified for NEP was renal failure due to stone disease (only one case). NEP was uncommon after RT, but was still more common than in the general population. We identified differences in the presentation and management of NEP after RT in comparison to the general population.

Diabetic ketoacidosis and hyperglycemic hyperosmolar syndrome after renal transplantation in the United States

BACKGROUND: The incidence and risk factors for diabetic ketoacidosis (diabetic ketoacidosis) and hyperglycemic hyperosmolar syndrome (hyperglycemic hyperosmolar syndrome, previously called non-ketotic hyperosmolar coma) have not been reported in a national population of renal transplant (renal transplantation) recipients. METHODS: We performed a historical cohort study of 39,628 renal transplantation recipients in the United States Renal Data System between 1 July 1994 and 30 June 1998, followed until 31 Dec 1999. Outcomes were hospitalizations for a primary diagnosis of diabetic ketoacidosis (ICD-9 code 250.1x) and hyperglycemic hyperosmolar syndrome (code 250.2x). Cox Regression analysis was used to calculate adjusted hazard ratios for time to hospitalization for diabetic ketoacidosis or hyperglycemic hyperosmolar syndrome. RESULTS: The incidence of diabetic ketoacidosis and hyperglycemic hyperosmolar syndrome were 33.2/1000 person years (PY) and 2.7/1000 PY respectively for recipients with a prior diagnosis of diabetes mellitus (DM), and 2.0/1000 PY and 1.1/1000 PY in patients without DM. In Cox Regression analysis, African Americans (AHR, 2.71, 95 %CI, 1.96-3.75), females, recipients of cadaver kidneys, patients age 33-44 (vs. >55), more recent year of transplant, and patients with maintenance TAC (tacrolimus, vs. cyclosporine) had significantly higher risk of diabetic ketoacidosis. However, the rate of diabetic ketoacidosis decreased more over time in TAC users than overall. Risk factors for hyperglycemic hyperosmolar syndrome were similar except for the significance of positive recipient hepatitis C serology and non-significance of female gender. Both diabetic ketoacidosis (AHR, 2.44, 95% CI, 2.10-2.85, p < 0.0001) and hyperglycemic hyperosmolar syndrome (AHR 1.87, 95% CI, 1.22-2.88, p = 0.004) were independently associated with increased mortality. CONCLUSIONS: We conclude that diabetic ketoacidosis and hyperglycemic hyperosmolar syndrome were associated with increased risk of mortality and were not uncommon after renal transplantation. High-risk groups were identified.

Factors associated with improved short term survival in obese end stage renal disease patients

PURPOSE

In contrast to its role in the general population, obesity, defined as body mass index (BMI) > or = 30 kg/m(2), has been associated with improved survival in patients with end stage renal disease (ESRD). This apparent benefit has not been explained.

METHODS

Using the United States Renal Data System (USRDS), we performed an historical cohort study on 151,027 patients initiated on ESRD therapy between January 1, 1995 and June 30, 1997, who never received renal transplants, and who had information sufficient to calculate BMI. We explored the association of various comorbidities present at the time of dialysis initiation (from HCFA Form 2728) with the presence of obesity by logistic regression, and the association of obesity with patient survival, including specific causes of death, by Cox regression adjusting for factors known to be associated with survival in this population.

RESULTS

Obese patients had an unadjusted two-year survival of 68% compared with 58% for non obese patients. Obesity was independently associated with a reduced risk of mortality among chronic dialysis patients (adjusted hazard ratio (AHR) 0.75, 95% confidence interval, 0.72-0.78), after controlling for all comorbidities and risk factors. However, there were significantly adverse interactions among whites (AHR 1.22, 1.14-1.30, across all causes of death) and females (AHR 1.12, 1.04-1.20, entirely due to an increased risk of infectious death).

CONCLUSIONS

Obesity in patients presenting with ESRD is associated independently with reduced all cause mortality; however, the relationship is complex and is stronger in African Americans. In addition, subgroup analysis suggests that obesity is associated with increased risk of infectious death in females.

Atrial fibrillation in chronic dialysis patients in the United States: risk factors for hospitalization and mortality

BACKGROUND

The incidence and risk factors for hospitalized atrial fibrillation have not been previously assessed in a national population of dialysis patients.

METHODS

We analyzed the United States Renal Data System (USRDS) Dialysis Morbidity and Mortality Study (DMMS) Wave II in a historical cohort study of hospitalized atrial fibrillation. Data from 3374 patients who started dialysis in 1996 with valid follow-up times were available for analysis, censored at the time of renal transplantation and followed until November 2000. Cox Regression analysis was used to model factors associated with time to first hospitalization for atrial fibrillation (ICD9 code 427.31x) adjusted for comorbidities, demographic factors, baseline laboratory values, blood pressures, dialysis modality, and cardioprotective medications.

RESULTS

The incidence density of atrial fibrillation was 12.5/1000 person years. Factors associated with atrial fibrillation were older age (> or = 71 years vs. <48 years), extremes (both high and low) of pre-dialysis systolic blood pressure, dialysis modality (hemodialysis vs. peritoneal dialysis), and digoxin use. Baseline use of coumadin was associated with reduced mortality in patients later hospitalized for atrial fibrillation.

CONCLUSIONS

Dialysis patients had a high incidence of atrial fibrillation. This risk was largely segregated among those with established risk factors for atrial fibrillation, and hemodialysis patients. Use of coumadin was associated with improved survival among patients later hospitalized for atrial fibrillation.

Body mass index and enrollment on the renal transplant waiting list in the United States

BACKGROUND

Previous studies of body mass index (BMI) and enrollment on the renal transplant waiting list have not analyzed a national population of chronic dialysis patients.

METHODS

161,265 patients in the United States Renal Data System (USRDS) initiated on end-stage renal disease (ESRD) therapy between 1 April 1995 and 30 June 1997 who had data sufficient to calculate BMI were analyzed in an historical cohort study. Cox Regression analysis was used to model the association of BMI and rates of listing for renal transplantation, censored for death and receipt of renal transplant, and adjusted for demographics, comorbidities in the Medical Evidence Form (2728) and in comparison with patient survival.

RESULTS

In univariate analysis, only patients with BMI <21.3 kg/m(2) had a statistically significant lower rate of listing compared to patients with BMI 24.5-28.6 kg/m(2) (6.1 vs. 7.5/100 person years). In Cox Regression analysis, patients with BMI <21.3 kg/m(2) had a 18% lower adjusted rate of listing and a 38% lower rate of survival, and patients with BMI >=24.5-28.7 had an 11% higher adjusted rate of listing and no significant difference in adjusted survival compared with patients with BMI>=28.7 kg/m(2). Caucasian females were disproportionately affected by high BMI.

CONCLUSIONS

Among ESRD patients, lower BMI was independently associated with reduced adjusted rates of listing. High BMI affected rates of listing disproportionately in caucasian females.

Total hip arthroplasty in chronic dialysis patients in the United States

BACKGROUND

The national incidence of and factors associated with total hip arthroplasty (THA) in chronic dialysis patients has never been reported.

METHODS

We therefore performed an historical cohort study of 375,857 chronic dialysis patients listed in the 2000 United States Renal Data System between 1 April 1995 and 31 December 1999 and followed-up until 14 May 2000. Primary outcomes were associations with hospitalizations for a primary discharge code of THA (ICD9 procedure code 81.51x) after initiation of dialysis.

RESULTS

Dialysis patients had a cumulative incidence of THA of 35 episodes/10,000 person-years, compared to 5.3/10,000 in the general population. The leading indication for THA was osteoarthritis of the hip and pelvis (58% of cases). However, the strongest risk factor for THA in dialysis patients was end-stage renal disease (ESRD) due to systemic lupus erythematosus (SLE, adjusted rate ratio (ARR), 6.80, 95% CI 4.62-10.03, in whom avascular necrosis of the hip was the most common indication, 68.4%). The database did not include information on use of corticosteroids. Diabetic recipients were significantly less likely to receive THA, as were males, and African Americans. Mortality after THA was 0.25% at thirty days and 30% at three years, not significantly different from the expected mortality of dialysis, adjusted for comorbidity.

CONCLUSIONS

The most common indication for THA in dialysis patients is osteoarthritis of the hip, similar to the general population. Patients with SLE are more likely to receive THA which is well tolerated and not associated with increased mortality in this population, perhaps reflecting selection bias due to appropriate screening for this elective procedure.

Hospitalized gastrointestinal bleeding and procedures after renal transplantation in the United States

The risk of hospitalized gastrointestinal bleeding (GIB) in renal transplant recipients has not been studied in a national renal transplant population. Therefore, 42,906 renal transplant recipients in the United States Renal Data System (USRDS) from 1 July 1994 - 30 June 1998 were analyzed in an historical cohort study of hospitalizations with a primary discharge diagnosis of GIB (ICD9 Code 578.9x) using Cox regression analysis. The 1997 National Hospital Discharge Survey was used to obtain rates of GIB for the general population. Renal transplant recipients had a cumulative incidence of hospitalizations for GIB of 334 events/100,000 person-years. In 1997, compared to the general population, renal transplant recipients had an age-adjusted rate ratio for GIB of 10.69 at one year of follow-up. The strongest risk factors for GIB in Cox regression analysis were graft loss (adjusted hazard ratio, 4.28 (2.84-6.47) and African American recipients who experienced allograft rejection (AHR, 3.04, 95% CI, 1.45-6.37). GIB was associated with increased all-cause mortality (hazard ratio 1.78, 95% CI, 1.39-2.28). GIB is significantly more common in renal transplant recipients than in the general population, and the strongest risk factors are graft loss and African Americans who experience rejection.

Hospitalized avascular necrosis after renal transplantation in the United States

BACKGROUND

The national incidence of and risk factors for hospitalized avascular necrosis (AVN) in renal transplant recipients has not been reported.

METHODS

This historical cohort study consisted of 42,096 renal transplant recipients enrolled in the United States Renal Data System (USRDS) between 1 July 1994 and 30 June 1998. The data source was USRDS files through May 2000. Associations with hospitalizations for a primary diagnosis of AVN (ICD-9 codes 733.4x) within three years after renal transplant were assessed in an intention-to-treat design by Cox regression analysis.

RESULTS

Recipients had a cumulative incidence of 7.1 episodes/1000 person-years from 1994 to 1998. The two-year incidence of AVN did not change significantly over time. Eighty-nine percent of the cases of AVN were due to AVN of the hip (733.42) and 60.2% of patients with AVN underwent total hip arthroplasty (THA); these percentages did not change significantly over time. In the Cox regression analysis, an earlier year of transplant, African American race [adjusted hazard ratio (AHR), 1.65, 95% confidence interval (CI) 1.33 to 2.03], allograft rejection (AHR 1.67, 95% CI 1.35 to 2.07), peritoneal dialysis (vs. hemodialysis; AHR 1.44, 95% CI 1.15 to 1.81), and diabetes (AHR 0.41, 95% CI 0.27 to 0.64) were the only factors independently associated with hospitalizations for AVN.

CONCLUSIONS

The incidence of AVN did not decline significantly over time in the renal transplant population. Patients with allograft rejection, African American race, peritoneal dialysis and earlier date of transplant were at the highest risk of AVN, while diabetic recipients were at a decreased risk.

Hospitalized poisonings after renal transplantation in the United States

BACKGROUND

The national incidence of and risk factors for hospitalized poisonings in renal transplant recipients has not been reported.

METHODS

Historical cohort study of 39,628 renal transplant recipients in the United States Renal Data System between 1 July 1994 and 30 June 1998. Associations with time to hospitalizations for a primary diagnosis of poisonings (ICD-9 codes 960.x-989.x) within three years after renal transplant were assessed by Cox Regression.

RESULTS

The incidence of hospitalized poisonings was 2.3 patients per 1000 person years. The most frequent causes of poisonings were immunosuppressive agents (25.3%), analgesics/antipyretics (14.1%), psychotropic agents (10.0%), and insulin/antidiabetic agents (7.1%). In Cox Regression analysis, low body mass index (BMI, <21.6 vs. >28.3 kg/m2, adjusted hazard ratio (AHR), 3.02, 95% CI, 1.45-6.28, and allograft rejection, AHR 1.83, 95% CI, 1.15-2.89, were the only factors independently associated with hospitalized poisonings. Hospitalized poisonings were independently associated with increased mortality (AHR, 1.54, 95% CI 1.22-1.92, p = 0.002).

CONCLUSIONS

Hospitalized poisonings were associated with increased mortality after renal transplantation. However, almost all reported poisonings in renal transplant recipients were due to the use of prescribed medications. Allograft rejection and low BMI were the only independent risk factors for poisonings identified in this population.

Hospitalizations for total hip arthroplasty after renal transplantation in the United States

The national incidence of and factors associated with total hip arthroplasty in renal transplant recipients has not been reported. We conducted an historical cohort study of 42096 renal transplant recipients in the United States between 1 July 1994 and 30 June 1998. Primary outcomes were associations with hospitalizations for a primary discharge code of total hip arthroplasty (ICD9 procedure code 81.51x) within 3 years after renal transplant using Cox regression. Renal transplant recipients had a cumulative incidence of total hip arthroplasty of 5.1 episodes/1000 person-years, which is 5-8 times higher than reported in the general population. Avascular necrosis of the hip was the most frequent primary diagnosis associated with total hip arthroplasty in this population (72% of cases). Repeat surgeries were performed in 27% of patients with avascular necrosis, vs. 15% with other diagnoses. Total hip arthroplasty was more frequent in transplant recipients who were older, African American, or who experienced allograft rejection. Mortality after total hip arthroplasty was 0.21% at 30 days and 15% at 3 years, similar to the mortality of all transplant recipients. The most common indication for total hip arthroplasty after renal transplant is avascular necrosis of the hip, in contrast to the general population. Although repeat surgeries are common, total hip arthroplasty is well tolerated and is not associated with increased mortality in this population.

Incident acute coronary syndromes in chronic dialysis patients in the United States

BACKGROUND

Patients on dialysis have a disproportionately high rate of cardiovascular disease (CVD). However, the incidence and risk factors for incident acute coronary syndromes (ACS) have not been previously assessed in dialysis patients.

METHODS

We analyzed the United States Renal Data System (USRDS) Dialysis Morbidity and Mortality Study (DMMS) Wave II in a historical cohort study of ACS. Data from 3374 patients who started dialysis in 1996 with valid follow-up times were available for analysis, censored at the time of renal transplantation and followed until March 2000. Cox regression analysis was used to model factors associated with time to first hospitalization for ACS (ICD9 code 410.x or 411.x) adjusted for comorbidities, demographic factors, baseline laboratory values, blood pressures and cholesterol levels, type of vascular access, dialysis adequacy, and cardioprotective medications (angiotensin-converting enzyme inhibitors, calcium channel blockers, HMG-CoA reductase inhibitors (statins), beta blockers, and aspirin). Follow-up was 2.19 +/- 1.14 years.

RESULTS

The incidence of ACS was 29/1000 person-years. Factors associated with ACS were older age, the extreme high and low ranges of serum cholesterol level, history of coronary heart disease (CHD), male gender, and diabetes. No cardioprotective medications including statins had a significant association with ACS in this study. However, medications known to reduce mortality after ACS were used in less than 50% of patients with known CHD at the start of the study, and statins were used in less than 10% of patients with CHD.

CONCLUSIONS

Dialysis patients had similar risk factors for ACS compared to the general population. Cardioprotective medications were not associated with a significant benefit, possibly due to their striking underutilization in this at-risk population.

Impact of HIV seropositivity on graft and patient survival after cadaveric renal transplantation in the United States in the pre highly active antiretroviral therapy (HAART) era: an historical cohort analysis of the United States Renal Data System

BACKGROUND

National statistics are presented for patient survival and graft survival in patients seropositive for the human immunodeficiency virus (HIV+) at the time of renal transplantation in the era prior to highly active antiretroviral therapy (HAART).

METHODS

Historical cohort analysis of 63, 210 cadaveric solitary renal transplant recipients with valid HIV serology entries in the United States Renal Data System (USRDS) from 1 January 1987 to 30 June 1997. The medical evidence form was also used for additional variables but, because of fewer available values, was analyzed in a separate model. Outcomes were patient characteristics and survival associated with HIV+ status.

RESULTS

Thirty-two patients (0.05%) in the study period were HIV+ at transplant. HIV+ patients were comparable to the national renal transplant population in terms of gender and ethnic distribution but were younger and had younger donors and better HLA matching than the USRDS population. Patient and graft three-year survival were significantly reduced in HIV+ recipients (53% graft, 83% patient survival) relative to the USRDS population (73% and 88%, respectively). In multivariate analysis, HIV+ status was independently associated with patient mortality and decreased graft survival in recipients of cadaveric kidney transplants.

CONCLUSIONS

This analysis was retrospective and may underestimate the number of HIV+ patients transplanted in the United States. Although the clinical details of patient selection for transplant were unknown, these results show HIV+ patients can have successful outcomes after cadaveric renal transplantation, although outcomes are significantly different from HIV- recipients.