The impact of cardiovascular disease and risk factor treatment on ethnic disparities in kidney transplant

Racial Differences in Medication Utilization for Secondary Prevention of Cardiovascular Disease in Kidney Transplant Recipients: A Post Hoc Analysis of the FAVORIT Trial Cohort

Rationale & Objective

Black kidney transplant recipients have higher prevalences of cardiovascular disease (CVD) risk factors and less intensive risk factor control than White kidney transplant recipients. Our objective was to evaluate racial disparities in receipt of statins and aspirin for secondary CVD prevention among kidney transplant recipients in the Folic Acid for Vascular Outcome Reduction in Transplantation (FAVORIT) trial.

Study Design

Cohort study.

Setting & Participants

FAVORIT participants of White, Black, and Other races from the United States and Canada with a history of CVD at study entry or who experienced a nonfatal CVD event during follow-up.

Predictor

Race.

Outcome

Receipt of statins and aspirin for secondary CVD prevention.

Analytical Approach

We used parametric (Weibull), proportional-hazards, interval-censored survival models to evaluate the independent association of race with receipt of statins and aspirin for secondary CVD prevention.

Results

Of the 4,110 kidney transplant recipients enrolled in FAVORIT trial, 978 met the inclusion criteria (78% White, 17% Black, and 6% Other race). Compared with the White race, Black and Other races were associated with lower hazards of receiving statins (Black race: adjusted HR, 0.76 [95% CI, 0.60-0.97]; Other race: adjusted HR, 0.87 [95% CI, 0.60-1.27]) and aspirin (Black race: adjusted HR, 0.85 [95% CI, 0.67-1.08]; Other race: adjusted HR, 0.63 [95% CI, 0.43-0.94]).

Limitations

Lack of granular information on potential indications or contraindications for aspirin or statin use for secondary CVD prevention.

Conclusions

Post hoc findings from the FAVORIT trial demonstrated that Black race was associated with a lower likelihood of receiving statins and Other race was associated with a lower likelihood of receiving aspirin for secondary CVD prevention. This represents a potential target to improve CVD care in non-White kidney transplant recipients.

Pharmacist-Led, Technology-Assisted Study to Improve Medication Safety, Cardiovascular Risk Factor Control, and Racial Disparities in Kidney Transplant Recipients

Introduction

Health disparities in African-American (AA) kidney transplant recipients compared with non-AA recipients are well established. Cardiovascular disease (CVD) risk control is a significant mediator of this disparity.

Objective

To assess the efficacy of improved medication safety, CVD risk control, and racial disparities in kidney transplant recipients.

Methods

Prospective, pharmacist-led, technology-aided, 6-month interventional clinical trial. A total of 60 kidney recipients with diabetes and hypertension were enrolled. Patients had to be at least one-year post transplant with stable graft function. Primary outcome measured included hypertension, diabetes, and lipid control using intent-to-treat analyses, with differences assessed between AA and non-AA recipients.

Results

The participants mean age was 59 years, with 42% being female and 68% being AA. Overall, patients demonstrated improvements in blood pressure <140/90 mmHg (baseline 50% vs. end of study 68%, p=0.054) and hemoglobin A1c <7% (baseline 33% vs. end of study 47%, p=0.061). AAs demonstrated a significant reduction from baseline in systolic blood pressure (-0.86 mmHg per month, p=0.026), which was not evident in non-AAs (-0.13 mmHg per month, p=0.865). Mean HgbA1c decreased from baseline in the overall group (-0.12% per month, p=0.003), which was similar within AAs (-0.11% per month, p=0.004) and non-AAs (-0.14% per month, p=0.029). There were no changes in low-density lipoproteins, triglycerides, or high-density lipoproteins over the course of the study. Medication errors were significantly reduced and self-reported medication adherence significantly improved over the course of the study.

Conclusion

These results demonstrate the potential efficacy of a pharmacist-led, technology-aided, educational intervention in improving medication safety, diabetes, and hypertension and reducing racial disparities in AA kidney transplant recipients. (ClinicalTrials.gov NCT02763943).

The impact of time-varying clinical surrogates on disparities in African-American kidney transplant recipients - a retrospective longitudinal cohort study

An improved understanding of the impact of clinical surrogates on disparities in African-American (AA) kidney transplantation (KTX) is needed. We conducted a 10-year retrospective longitudinal cohort study of electronically abstracted clinical data assessing the impact of surrogates on disparities in KTX. Clinical surrogates were assessed by posttransplant year (1, 2, 3 or 4) and defined as acute rejection (Banff ≥1A), mean SBP >140 mmHg, tacrolimus variability (CV) >40%, mean glucose >160 mg/dl and mean hemoglobin <10 g/dl. We utilized landmark methodology to minimize immortal time bias and logistic and survival regression to assess outcomes; 1610 KTX were assessed (54.2% AAs), with 1000, 468, 368 and 303 included in the year 1, 2, 3 and 4 complete case analyses, respectively. AAs had significantly higher odds of developing a clinical surrogate, which increased in posttransplant years three and four [OR year 1 1.99 (1.38-2.88), year 2 1.77 (1.20-2.62), year 3 2.35 (1.49-3.71), year 4 2.85 (1.72-4.70)]. Adjusting for the five clinical surrogates in survival models explained a significant portion of the higher risks of graft loss in AAs in post-transplant years three and four. Results suggest focusing efforts on improving late clinical surrogate management within AAs may help mitigate racial disparities in KTX.

Overall Graft Loss Versus Death-Censored Graft Loss: Unmasking the Magnitude of Racial Disparities in Outcomes Among US Kidney Transplant Recipients

BACKGROUND

Black kidney transplant recipients experience disproportionately high rates of graft loss. This disparity has persisted for 40 years, and improvements may be impeded based on the current public reporting of overall graft loss by US regulatory organizations for transplantation.

METHODS

Longitudinal cohort study of kidney transplant recipients using a data set created by linking Veterans Affairs and US Renal Data System information, including 4918 veterans transplanted between January 2001 and December 2007, with follow-up through December 2010. Multivariable analysis was conducted using 2-stage joint modeling of random and fixed effects of longitudinal data (linear mixed model) with time to event outcomes (Cox regression).

RESULTS

Three thousand three hundred six non-Hispanic whites (67%) were compared with 1612 non-Hispanic black (33%) recipients with 6.0 ± 2.2 years of follow-up. In the unadjusted analysis, black recipients were significantly more likely to have overall graft loss (hazard ratio [HR], 1.19; 95% confidence interval [95% CI], 1.07-1.33), death-censored graft loss (HR, 1.67; 95% CI, 1.45-1.92), and lower mortality (HR, 0.83; 95% CI, 0.72-0.96). In fully adjusted models, only death-censored graft loss remained significant (HR, 1.38; 95% CI, 1.12-1.71; overall graft loss [HR, 1.08; 95% CI, 0.91-1.28]; mortality [HR, 0.84; 95% CI, 0.67-1.06]). A composite definition of graft loss reduced the magnitude of disparities in blacks by 22%.

CONCLUSIONS

Non-Hispanic black kidney transplant recipients experience a substantial disparity in graft loss, but not mortality. This study of US data provides evidence to suggest that researchers should focus on using death-censored graft loss as the primary outcome of interest to facilitate a better understanding of racial disparities in kidney transplantation.

Outcome disparities between African Americans and Caucasians in contemporary kidney transplant recipients

BACKGROUND

Racial disparities in African-American (AA) kidney transplant have persisted for nearly 40 years, with limited data available on the scope of this issue in the contemporary era of transplantation.

METHODS

Descriptive retrospective cohort study of US registry data including adult solitary kidney transplants between Jan 1, 2005 to Dec 31, 2009.

RESULTS

60,695 recipients were included; 41,426 Caucasians (68%) and 19,269 AAs (32%). At baseline, AAs were younger, had lower college graduation rates, were more likely to be receiving public health insurance and have diabetes. At one-year post-transplant, AAs had 62% higher risk of graft loss (RR 1.62, 95% CI 1.50-1.75) which increased to 93% at five years (RR 1.93, 95% CI 1.85-2.01). Adjusted risk of graft loss, accounting for baseline characteristics, was 60% higher in AAs (HR 1.61 [1.52-1.69]). AAs had significantly higher risk of acute rejection and delayed graft function.

CONCLUSION

AAs continue to experience disproportionately high rates of graft loss within the contemporary era of transplant, which are related to a convergence of an array of socioeconomic and biologic risk factors.

Impact of Cardiovascular Risk Factors on Graft Outcome Disparities in Black Kidney Transplant Recipients

Although outcome inequalities for non-Hispanic black (NHB) kidney transplant recipients are well documented, there is paucity in data assessing the impact of cardiovascular disease (CVD) risk factors on this disparity in kidney transplantation. This was a longitudinal study of a national cohort of veteran kidney recipients transplanted between January 2001 and December 2007. Data included baseline characteristics acquired through the United States Renal Data System linked to detailed clinical follow-up information acquired through the Veterans Affairs electronic health records. Analyses were conducted using sequential multivariable modeling (Cox regression), incorporating blocks of variables into iterative nested models; 3139 patients were included (2095 non-Hispanic whites [66.7%] and 1044 NHBs [33.3%]). NHBs had a higher prevalence of hypertension (100% versus 99%; P<0.01) and post-transplant diabetes mellitus (59% versus 53%; P<0.01) with reduced control of hypertension (blood pressure <140/90 60% versus 69%; P<0.01), diabetes mellitus (A1c <7%, 35% versus 47%; P<0.01), and low-density lipoprotein (<100 mg/dL, 55% versus 61%; P<0.01). Adherence to medications used to manage CVD risk was significantly lower in NHBs. In the fully adjusted models, the independent risk of graft loss in NHBs was substantially reduced (unadjusted hazard ratio, 2.00 versus adjusted hazard ratio, 1.49). CVD risk factors and control reduced the influence of NHB race by 9% to 18%. Similar trends were noted for mortality, and estimates were robust across in sensitivity analyses. These results demonstrate that NHB kidney transplant recipients have significantly higher rates of CVD risk factors and reduced CVD risk control. These issues are likely partly related to medication nonadherence and meaningfully contribute to racial disparities for graft outcomes.

Does African American Race Impact Statin Efficacy in Renal Transplant Outcomes?

There is a lack of studies assessing if race impacts the efficacy of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) inhibitor ("statin") therapy on renal transplantation (RTx) outcomes. We examined the association between statin therapy and RTx outcomes, while concurrently quantifying the effect modification African American (AA) race has on statin efficacy.This was a retrospective longitudinal cohort study of solitary adult RTx (n = 1176) between June 2005 and May 2013. The Cox proportional hazard model was used to examine the impact of statin therapy on graft loss, death, and acute rejection and determine if significant interactions exist between statin therapy and race. Models were adjusted for demographics, socioeconomic status, cardiovascular history, medication use, and transplant characteristics.AAs (n = 624) and non-African Americans (n = 552) were equally likely to receive statin therapy (P = 0.922). Mean LDL and TGs in AA were 94 mg/dL and 133 mg/dL compared to 90 mg/dL and 163 mg/dL in non-AA, respectively. After adjusting for confounders, high statin users had 52% lower risk of developing graft loss (HR 0.48, 95% CI 0.29-0.80) and a nonstatistically significant reduction in death (HR 0.50, 95% CI 0.23-1.06) compared to low statin users. Acute rejection was not significantly influenced by statin use (HR 0.77 95% CI 0.46-1.27). There was a significant interaction between race and statin therapy for death (P = 0.007), but not for graft loss (P = 0.121) or rejection (P = 0.605). After stratifying by race, high statin use reduced the risk of death in AAs (HR 0.43, 95% CI 0.20-0.94), but not in non-AAs (HR 1.09, 95% CI 0.49-2.44).High statin use reduces the risk of graft loss in RTx, with a mortality benefit in AAs compared to non-AA, despite similar LDL levels. These results suggest a compelling reason to optimize statin therapy in renal transplant recipients (RTR), especially in AAs.

Significant racial differences in the key factors associated with early graft loss in kidney transplant recipients

BACKGROUND

There is continued and significant debate regarding the salient etiologies associated with graft loss and racial disparities in kidney transplant recipients.

METHODS

This was a longitudinal cohort study of all adult kidney transplant recipients, comparing patients with early graft loss (<5 years) to those with graft longevity (surviving graft with at least 5 years of follow-up) across racial cohorts [African-American (AA) and non-AA] to discern risk factors.

RESULTS

524 patients were included, 55% AA, 151 with early graft loss (29%) and 373 with graft longevity (71%). Consistent within both races, early graft loss was significantly associated with disability income [adjusted odds ratio (AOR) 2.2, 95% CI 1.1-4.5], Kidney Donor Risk Index (AOR 3.2, 1.4-7.5), rehospitalization (AOR 2.1, 1.0-4.4) and acute rejection (AOR 4.4, 1.7-11.6). Unique risk factors in AAs included Medicare-only insurance (AOR 8.0, 2.3-28) and BK infection (AOR 5.6, 1.3-25). Unique protective factors in AAs included cardiovascular risk factor control: AAs with a mean systolic blood pressure <150 mm Hg had 80% lower risk of early graft loss (AOR 0.2, 0.1-0.7), while low-density lipoprotein <100 mg/dl (AOR 0.4, 0.2-0.8), triglycerides <150 mg/dl (AOR 0.4, 0.2-1.0) and hemoglobin A1C <7% (AOR 0.2, 0.1-0.6) were also protective against early graft loss in AA, but not in non-AA recipients.

CONCLUSIONS

AA recipients have a number of unique risk factors for early graft loss, suggesting that controlling cardiovascular comorbidities may be an important mechanism to reduce racial disparities in kidney transplantation.

Are thiazide diuretics safe and effective antihypertensive therapy in kidney transplant recipients?

BACKGROUND/AIMS

There are no published studies assessing the safety and efficacy of thiazides as antihypertensives in kidney transplantation (KTX).

METHODS

This was a longitudinal retrospective cohort study conducted in adult KTX recipients. Patients were grouped based on receiving thiazides following KTX. Safety and efficacy comparisons were made between thiazide recipients and unexposed patients, as well as change in blood pressure (BP) within thiazide patients.

RESULTS

1,093 patients were included (thiazide group: 108, unexposed group: 985). Mean follow-up was 7.3 ± 4.5 years. Thiazide recipients were older (53 ± 11 vs. 48 ± 13 years, p < 0.001) and more likely to be female (52 vs. 41%, p = 0.023) and have pre-KTX hypertension (97 vs. 88%, p = 0.004) or diabetes (36 vs. 27%, p = 0.035). After controlling for baseline differences, safety analysis revealed thiazide recipients were not more likely to be readmitted to the hospital, but were at higher risk to develop hyperkalemia (56 vs. 38%, p < 0.001) or hypokalemia (28 vs. 18%, p = 0.010), with similar rates of hypotension, decreased estimated glomerular filtration rate, graft loss and death. Efficacy analysis demonstrated systolic (147 ± 17 to 139 ± 18 mm Hg, p < 0.001) and diastolic (79 ± 9 to 77 ± 11 mm Hg, p < 0.001) BPs were significantly reduced after thiazide initiation. Compared to unexposed patients, thiazide recipients had higher mean BPs during the entire follow-up (142/78 vs. 136/77, p < 0.001), with similar BPs while on thiazides and comparable rates of goal BPs (<130/80 mm Hg, 32 vs. 36%, p = 0.219).

CONCLUSIONS

In KTX, based on long-term outcomes, thiazides appear to be safe and effective antihypertensives; in the short-term, thiazides may increase the risk of developing potassium disturbances.