Understanding medical care of transplant recipients through integrated registry and pharmacy claims data

Statins in Kidney Transplant Recipients: Usage, All-Cause Mortality, and Interactions with Maintenance Immunosuppressive Agents

SIGNIFICANCE STATEMENT

Cardiovascular diseases account for 32% of deaths among kidney transplant recipients. Statin therapy is common in this population. However, its effect on mortality prevention remains unclear among kidney transplant recipients, whose clinical risk profile might be unique because of concomitant immunosuppressive therapy. In this national study of 58,264 single-kidney transplant recipients, statin use was associated with a 5% decrease in mortality. More importantly, this protective association was stronger among those who used a mammalian target of rapamycin (mTOR) inhibitor for immunosuppression (27% decrease in mTOR inhibitor users versus 5% in nonusers). Our results suggest that statin therapy may reduce mortality in kidney transplant recipients and that the strength of this protective association may vary by immunosuppression regimen.

BACKGROUND

Cardiovascular diseases are the leading cause of mortality in kidney transplant (KT) recipients, accounting for 32% of deaths. Statins are widely used in KT recipients, but effectiveness for preventing mortality remains unclear in this population, especially because of interaction between statins and immunosuppressive agents. We analyzed a national cohort to assess the real-world effectiveness of statins for reducing all-cause mortality in KT recipients.

METHODS

We studied statin use and mortality among 58,264 adults (18 years or older) who received single kidneys between 2006 and 2016 and had Medicare part A/B/D. Statin use was ascertained from Medicare prescription drug claims and deaths from Center for Medicare and Medicaid Services records. We estimated the association of statin use with mortality using multivariable Cox models, with statin use as a time-varying exposure and immunosuppression regimen as effect modifiers.

RESULTS

Statin use increased from 45.5% at KT to 58.2% at 1-year post-KT to 70.9% at 5-year post-KT. We observed 9785 deaths over 236,944 person-years. Overall, statin use was significantly associated with lower mortality (adjusted hazard ratio [aHR], 0.95; 95% confidence interval [CI], 0.90 to 0.99). The strength of this protective association varied by calcineurin inhibitor use (among tacrolimus users, aHR, 0.97; 95% CI, 0.92 to 1.03 versus among calcineurin nonusers, aHR, 0.72; 95% CI, 0.60 to 0.87; interaction P =0.002), mammalian target of rapamycin (mTOR) inhibitor use (among mTOR inhibitor users, aHR, 0.73; 95% CI, 0.57 to 0.92 versus among nonusers, aHR, 0.95; 95% CI, 0.91 to 1.00; interaction P =0.03), and mycophenolate use (among mycophenolate users, aHR, 0.96; 95% CI, 0.91 to 1.02 versus among nonusers, aHR, 0.76; 95% CI, 0.64 to 0.89; interaction P =0.002).

CONCLUSION

Real-world evidence supports statin therapy for reducing all-cause mortality in KT recipients. Effectiveness might be greater when combined with mTOR inhibitor-based immunosuppression.

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.

Use of Statins in Kidney Transplant Recipients in Norway

Kidney transplant recipients (KTRs) experience increased risk of cardiovascular disease. Guidelines recommend HMG-CoA reductase inhibitor (statin) therapy when tolerated. We aimed to study changes in the prescription of statins and patients’ adherence to treatment over time. A population-based observational study utilizing linked data from the Norwegian Renal Registry (national coverage of 99.9%) and the Norwegian Prescription Database was performed. Data from a total of 2250 first KTRs were included (mean age—54 years, 69% men). Dispensed prescriptions of statins and immunosuppressants for the period 2004–2016 for all first KTRs engrafted in the period 2005–2015 were analyzed. Seventy-two percent received statins the first year after kidney transplantation and the proportion increased with age. The proportion receiving a statin varied according to the time frame of transplantation (77% in 2005–2010 vs. 66% in 2012–2015). Among new users of statins, 82% of the patients were adherent both the second and third year after kidney transplantation, while the corresponding figure for those already receiving statins before transplantation was 97%. Statin continuation rates in KTRs were high. In conclusion, our findings show a slightly lower overall proportion of patients receiving statins after kidney transplants than the national target level of 80%. The proportion of statin users increased with the age of the KTRs but showed a decreasing trend as time progressed.

Hydroxychloroquine and maintenance immunosuppression use in kidney transplant recipients: Analysis of linked US registry and claims data

Hydroxychloroquine (HCQ) is an antimalarial drug with immunomodulatory effects used to treat systemic lupus erythematosus (SLE) and scleroderma. The antiviral effects of HCQ have raised attention in the context of the COVID-19 pandemic, although safety is controversial. We examined linkages of national transplant registry data with pharmaceutical claims and Medicare billing claims to study HCQ use among Medicare-insured kidney transplant recipients with SLE or scleroderma (2008-2017; N = 1820). We compared three groups based on immunosuppression regimen 7 months-to-1 year post transplant: (a) tacrolimus (Tac) + mycophenolic acid (MPA) + prednisone (Pred) (referent group, 77.7%); (b) Tac + MPA + Pred + HCQ (16.5%); or (c) other immunosuppression + HCQ (5.7%). Compared to the referent group, recipients treated with other immunosuppression + HCQ had a 2-fold increased risk of abnormal ECG or QT prolongation (18.9% vs. 10.7%; aHR,_1.12 1.96_3.42 , p = .02) and ventricular arrhythmias (15.2% vs. 11.4%; aHR,_1.00 1.81_3.29 , p = .05) in the >1-to-3 years post-transplant. Tac + MPA + Pred + HCQ was associated with increased risk of ventricular arrhythmias (13.5% vs. 11.4%; aHR,_1.02 1.54_2.31 , p = .04) and pancytopenia (35.9% vs. 31.4%; aHR,_1.03 1.31_1.68 , p = .03) compared to triple immunosuppression without HCQ. However, HCQ-containing regimens were not associated with an increased risk of death or graft failure. HCQ may be used safely in selected kidney transplant recipients in addition to their maintenance immunosuppression, although attention to arrhythmias is warranted.

Understanding antihypertensive medication use after living kidney donation through linked national registry and pharmacy claims data

BACKGROUND

Use of antihypertensive medications (AHM) after living kidney donation is not well described.

METHODS

We examined a database wherein national transplant registry data for 4,650 living kidney donors in 1987-2007 were linked to pharmacy claims from a US private health insurer (2000-2007 claims) to identify post-donation AHM fills. Cox regression with left- and right-censoring was used to estimate the frequencies and relative likelihood (adjusted hazards ratios, aHR) of post-donation AHM fills according to donor demographic traits. Medication possession ratio (MPRs), defined as (days of AHM dispensed)/(days observed), were also compared among donors and non-donor general beneficiaries.

RESULTS

Overall, 17.8% of the sample filled at least one AHM by 5 years post-donation. As compared with White living donors, African-Americans had 37% higher relative likelihood of any AHM use after donation (aHR 1.37, p < 0.0007), including significantly higher likelihoods of filling diuretics (aHR 2.25, p < 0.0001), ACEi/ARBs (aHR 1.46, p < 0.01), calcium channel blockers (aHR 1.56, p = 0.03), and vasodilators/other agents (aHR 2.17, p = 0.03). MPRs for any AHM and subcategories were lower among donors compared with age- and sex-matched non-donors. However, AHM MPRs rose in donors with multiple hypertension diagnoses, and prescription fill exposure for all AHM classes except diuretics was similar among donors and general non-donors with ≥ 3 hypertension diagnoses.

CONCLUSIONS

While AHM requirements are lower after kidney donation than among unscreened general persons, racial variation in AHM use occurs in privately insured donors. Demonstration of pharmaceutical care needs of insured donors supports the need for long-term follow-up and healthcare access for all donors.