Kidney Function and Physical Performance Decline: The Brain in Kidney Disease (BRINK) Cohort Study.

Rationale & Objective: Patients with kidney failure have poor physical performance, but its trajectory is less clear. We examined physical function over the course of kidney disease, including the transition to dialysis. Study Design: Observational cohort. Setting & Participants: Community-dwelling adults aged ≥45 years in the Brain in Kidney Disease (BRINK) cohort study. Predictors: Estimated glomerular filtration rate (eGFR) and urine albumin to creatinine ratio (UACR). Outcomes: Change in physical performance using the Short Physical Performance Battery (SPPB) (primary) and gait speed (secondary). Analytical Approach: Linear mixed effects regression models. Results: The analytical cohort included 562 participants with mean age of 69.3 (SD, 9.8) years followed for up to 63 months. In total, 49.8% were women. In addition, 79.9% self-identified as White, and 15.3% self-identified as Black. In total, 48.8% had diabetes. Mean eGFR at baseline was 48.1 (SD, 24.3) mL/min/1.73 m2. In unadjusted analysis, lower eGFR was associated with greater decline in SPPB score (P trend < 0.001). The decline in SPPB score was larger among participants with lower eGFR, with a gradient from -0.15 (95% CI, -0.23 to -0.07) points per year for participants with eGFR ≥60 mL/min/1.73 m2 to -0.56 (95% CI, -0.84 to -0.27) for participants with eGFR <15 mL/min/1.73 m2 and -0.61 (95% CI, -0.90 to -0.33) after dialysis initiation. In covariate-adjusted models, SPPB did not continue to decline after dialysis initiation. In secondary analyses evaluating change in gait speed, gait speed continued to decline after dialysis initiation. Higher UACR was also associated with a greater decline in SPPB score and gait speed in unadjusted and adjusted models. Limitations: Small number of participants started dialysis. Conclusions: We found a graded association of chronic kidney disease stage and albuminuria with decline in physical performance. The decline in SPPB was not accelerated after dialysis initiation in covariate-adjusted models, whereas gait speed continued to decline.

Physical function is an important patient-centered outcome in chronic kidney disease (CKD), but whether physical performance changes as kidney disease progresses or when patients start dialysis is not well understood. We found that measures of physical performance, like strength and walking speed, worsened as kidney disease worsened. However, 1 combination of physical performance tests appeared stable (rather than getting worse) after starting dialysis compared to those with very advanced CKD who had not yet started dialysis, while gait speed continued to get worse. This information may help counsel patients who are learning about CKD and considering treatment options. It may also help guide research on interventions to improve physical function in patients with CKD.

Development and validation of a risk model for hospital-acquired venous thrombosis: the Medical Inpatients Thrombosis and Hemostasis study.

BACKGROUND: Regulatory organizations recommend assessing hospital-acquired (HA) venous thromboembolism (VTE) risk for medical inpatients. OBJECTIVES: To develop and validate a risk assessment model (RAM) for HA-VTE in medical inpatients using objective and assessable risk factors knowable at admission. METHODS: The development cohort included people admitted to medical services at the University of Vermont Medical Center (Burlington, Vermont) between 2010 and 2019, and the validation cohorts included people admitted to Hennepin County Medical Center (Minneapolis, Minnesota), University of Michigan Medical Center (Ann Arbor, Michigan), and Harris Health Systems (Houston, Texas). Individuals with VTE at admission, aged <18 years, and admitted for <1 midnight were excluded. We used a Bayesian penalized regression technique to select candidate HA-VTE risk factors for final inclusion in the RAM. RESULTS: The development cohort included 60 633 admissions and 227 HA-VTE, and the validation cohorts included 111 269 admissions and 651 HA-VTE. Seven HA-VTE risk factors with t statistics ≥1.5 were included in the RAM: history of VTE, low hemoglobin level, elevated creatinine level, active cancer, hyponatremia, increased red cell distribution width, and malnutrition. The areas under the receiver operating characteristic curve and calibration slope were 0.72 and 1.10, respectively. The areas under the receiver operating characteristic curve and calibration slope were 0.70 and 0.93 at Hennepin County Medical Center, 0.70 and 0.87 at the University of Michigan Medical Center, and 0.71 and 1.00 at Harris Health Systems, respectively. The RAM performed well stratified by age, sex, and race. CONCLUSION: We developed and validated a RAM for HA-VTE in medical inpatients. By quantifying risk, clinicians can determine the potential benefits of measures to reduce HA-VTE.

Symptom Trajectories in the Electronic Health Record during the Transition to Maintenance Dialysis.

How symptoms recorded in the electronic health record change during the transition to dialysis has not been fully explored. We used the Optum deidentified Integrated Claims-Clinical dataset to identify individuals with CKD stages 4 or 5 who transitioned to dialysis. We searched structured data elements from clinical notes, identified by natural language processing, for symptoms recorded across weekly intervals in the 6 months before and after dialysis initiation and estimated changes in the odds of a symptom being recorded with an interrupted time series analysis using segmented logistic regression. The cohort comprised 728 individuals (aged 68±13 years, 44% women, 56% White, 30% Black). Before dialysis initiation, 83% were recorded as having pain, 68% fatigue/weakness, 66% shortness of breath, 61% nausea/vomiting, and 37% difficulty concentrating. Before dialysis initiation, odds of pain being recorded increased (slope: odds ratio [OR] 1.02 per week, 95% confidence interval [CI], 1.01 to 1.03); initiation was associated with a decrease (intercept change: OR 0.70, 95% CI, 0.59 to 0.82). After initiation, odds of pain were unchanged (postdialysis slope: OR 1.00 per week, 95% CI, 0.99 to 1.01), although this represented an improved trajectory relative to the predialysis period (change in slope: OR 0.98 per week, 95% CI, 0.96 to 0.99). For fatigue/weakness, odds increased before initiation (OR 1.03 per week, 95% CI, 1.02 to 1.04) but decreased on initiation (OR 0.62, 95% CI, 0.51 to 0.75) and thereafter (OR 0.98 per week, 95% CI, 0.97 to 0.99), representing a reduction in slope (OR 0.95 per week, 95% CI, 0.94 to 0.97). Patterns for shortness of breath, nausea/vomiting, and difficulty concentrating were similar to those of pain. Thus, the odds of five key symptoms being recorded in the electronic health record increased over time in the 6 months before dialysis initiation, decreased immediately on initiation, and, generally, remained unchanged in the 6 months thereafter.

Development of a computable phenotype using electronic health records for venous thromboembolism in medical inpatients: the Medical Inpatient Thrombosis and Hemostasis study.

Background: Accurate and efficient methods to identify venous thromboembolism (VTE) events in hospitalized people are needed to support large-scale studies. Validated computable phenotypes using a specific combination of discrete, searchable elements in electronic health records to identify VTE and distinguish between hospital-acquired (HA)-VTE and present-on-admission (POA)-VTE would greatly facilitate the study of VTE, obviating the need for chart review. Objectives: To develop and validate computable phenotypes for POA- and HA-VTE in adults hospitalized for medical reasons. Methods: The population included admissions to medical services from 2010 to 2019 at an academic medical center. POA-VTE was defined as VTE diagnosed within 24 hours of admission, and HA-VTE as VTE identified more than 24 hours after admission. Using discharge diagnosis codes, present-on-admission flags, imaging procedures, and medication administration records, we iteratively developed computable phenotypes for POA-VTE and HA-VTE. We assessed the performance of the phenotypes using manual chart review and survey methodology. Results: Among 62,468 admissions, 2693 had any VTE diagnosis code. Using survey methodology, 230 records were reviewed to validate the computable phenotypes. Based on the computable phenotypes, the incidence of POA-VTE was 29.4 per 1000 admissions and that of HA-VTE was 3.6 per 1000 admissions. The POA-VTE computable phenotype had positive predictive value and sensitivity of 88.8% (95% CI, 79.8%-94.0%) and 99.1% (95% CI, 94.0%- 99.8%), respectively. Corresponding values for the HA-VTE computable phenotype were 84.2% (95% CI, 60.8%-94.8%) and 72.3% (95% CI, 40.9%-90.8%). Conclusion: We developed computable phenotypes for HA-VTE and POA-VTE with adequate positive predictive value and sensitivity. This phenotype can be used in electronic health record data-based research.

Association of Nondihydropyridine Calcium Channel Blockers Versus ß-Adrenergic Receptor Blockers With Risk of Heart Failure Hospitalization.

Heart failure (HF) with preserved ejection fraction (HFpEF) and atrial fibrillation (AF) are interrelated and often coexisting conditions in older adults. Although equally recommended, nondihydropyridine calcium channel blockers (non-DHP CCBs), such as diltiazem and verapamil, are less often used than ß blockers. Because recent studies suggested that ß-blocker use in both HFpEF and AF may increase the risk for HF, we tested whether non-DHP CCBs were associated with lower HF hospitalization risk than ß blockers. We examined fee-for-service Medicare beneficiaries who were aged ≥66 years, had HFpEF or AF, and newly initiated a ß blocker (n = 83,458) or non-DHP CCB (n = 18,924) from 2014 to 2018. The outcomes of HF hospitalization and all-cause mortality were analyzed using multivariable-adjusted Cox regression in the full cohort and, separately, in the subset without a recent hospital or skilled nursing discharge. Follow-up was analyzed using 2 frameworks: intention-to-treat and censored-at-drug-switch-or-discontinuation. There was a modestly protective association of non-DHP CCBs for the risk of HF hospitalization. Before drug switch or discontinuation, the use of diltiazem or verapamil was associated with decreased risk of HF hospitalization in the full cohort (hazard ratio [HR] 0.90, 95% confidence interval [CI] 0.81 to 1.00, p = 0.05) and in the subgroup (HR 0.70, 95% CI 0.56 to 0.89, p = 0.003). However, the association with all-cause mortality tended to favor ß blockers, including in the intention-to-treat analysis (HR 1.21, 95% CI 1.17 to 1.25, p <0.001). In conclusion, compared with ß blockers, the initiation of diltiazem or verapamil in patients with HFpEF or AF may be associated with fewer HF hospitalization events but also with more all-cause deaths.

Hemodialysis Access Type and Access Patency Loss: An Observational Cohort Study.

Rationale & Objective: Access patency outcomes for arteriovenous fistulas (AVFs) as compared with arteriovenous grafts (AVGs) in patients receiving hemodialysis (HD) who have achieved a functioning permanent access are not fully explored. Study Design: Observational cohort study. Setting & Population: Fee-for-service Medicare beneficiaries aged ≥18 years with kidney failure who were newly using a permanent access for maintenance HD from the United States Renal Data System (2010-2015). Patients using an oral anticoagulant were excluded. Exposure: AVG or AVF. Outcomes: Loss of primary unassisted, primary assisted, and secondary patency. Analytical Approach: Outcomes were characterized using cumulative incidence curves, and HRs adjusted for sociodemographic and clinical factors were estimated for the comparison of AVF versus AVG. Results: The cohort included 60,329 and 17,763 patients newly using an AVF and AVG, respectively, for HD. Over 3 years of follow-up, AVG users, compared to AVF users, had a higher cumulative incidence of loss of primary unassisted patency (87% vs 69%; HR, 1.56; 95% CI, 1.52-1.60), loss of primary assisted patency (69% vs 25%; HR, 3.79; 95% CI, 3.67-3.92), and loss of secondary patency (22% vs 10%; HR, 2.03; 95% CI, 1.92-2.16). Stratified analyses revealed differences by subgroups; in particular, incidence of patency loss was higher among patients who underwent prior interventions to maintain prefunctional access patency and Black patients. Limitations: This analysis focused on outcomes occurring after first successful use of a permanent access and thus does not inform about risk of patency loss during access maturation. Conclusions: Among patients with kidney failure who successfully used a permanent access for HD, patency loss was consistently substantially higher in those using AVGs compared with AVFs. New interventions, such as prophylactic drugs, are needed to improve access longevity and reduce the need for invasive interventions, particularly among patients unable to receive a fistula.

The relative risk of bleeding after medical hospitalization: the medical inpatient thrombosis and hemorrhage study.

BACKGROUND: Clinically relevant bleeding risk in discharged medical patients is underestimated and leads to rehospitalization, morbidity, and mortality. Studies assessing this risk are lacking. OBJECTIVE: The aim of this study was to develop and validate a computable phenotype for clinically relevant bleeding using electronic health record (EHR) data and quantify the relative and absolute risks of this bleeding after medical hospitalization. METHODS: We conducted an observational cohort study of people receiving their primary care at sites affiliated with an academic medical center in northwest Vermont, United States. We developed a computable phenotype using EHR data (diagnosis codes, procedure codes, laboratory, and transfusion data) and validated it by manual chart review. Cox proportional hazard models with hospitalization modeled as a time-varying covariate were used to estimate clinically relevant bleeding risk. RESULTS: The computable phenotype had a positive predictive value of 80% and a negative predictive value of 99%. The bleeding rate in individuals with no medical hospitalizations in the past 3 months was 2.9 per 1000 person-years versus 98.9 per 1000 person-years in those who were discharged in the past 3 months. This translates into a hazard ratio (95% CI) of clinically relevant bleeding of 22.9 (18.9, 27.7), 13.0 (10.0, 16.9), and 6.8 (4.7, 9.8) over the first, second, and third months after discharge, respectively. CONCLUSION: We developed and validated a computable phenotype for clinically relevant bleeding and determined its relative and absolute risk in the 3 months after medical hospitalization discharge. The high rates of bleeding observed underscore the clinical importance of capturing and further studying bleeding after medical discharge.

Prescribing Patterns of Direct-Acting Oral Anticoagulants in Patients With Atrial Fibrillation and Chronic Kidney Disease: A Retrospective Cohort Analysis.

BACKGROUND: The association of patient and prescriber characteristics with use of warfarin versus direct-acting oral anticoagulants (DOACs) in patients with atrial fibrillation (AF) and chronic kidney disease (CKD) is not well studied. METHODS: The 20% Centers for Medicare & Medicaid Services Parts A, B, and D claims data from 2010 to 2017 were used to identify patients with stage 3, 4, or 5 CKD and AF who received a DOAC (apixaban, dabigatran, rivaroxaban) or warfarin. Prescribers were categorized as cardiologists, primary care providers (PCPs), and others. Using logistic regression, we estimated odds ratios (ORs) for the association of baseline characteristics and prescriber specialty with first use of a DOAC, relative to warfarin. RESULTS: We identified 22,739 individuals with CKD who were newly initiated on oral anticoagulation for AF. New DOAC prescriptions increased from 490 in 2011 to 3261 in 2017, and displaced warfarin over time (1849, 2011; 945, 2017). By Q4 of 2014, cardiologists prescribed DOACs as initial treatment more frequently than warfarin, but non-cardiologists did not do so until 2015. As of 2017, apixaban was the most widely prescribed anticoagulant, comprising 56% and 50% of prescriptions by cardiologists and non-cardiologists, respectively. PCPs (OR 0.54, 0.51-0.58) and other providers (OR 0.55, 0.51-0.59) were less likely than cardiologists to prescribe DOACs. CONCLUSIONS: DOAC prescriptions, particularly apixaban, increased over time and gradually displaced warfarin. The total number of patients with AF and CKD receiving anticoagulation increased over time. Cardiologists increased DOAC prescriptions more rapidly than non-cardiologists.

Hemodialysis Vascular Access and Risk of Major Bleeding, Thrombosis, and Cardiovascular Events: A Cohort Study.

Rationale & Objective: The risks of major bleeding, thrombosis, and cardiovascular events are elevated in patients receiving maintenance hemodialysis (HD). Our objective was to compare the risk of these outcomes in HD according to the permanent vascular access type. Study Design: Observational cohort study. Setting & Participants: Using data from the United States Renal Data System (2010-2015), we included patients with kidney failure who were greater than 18 years, had Medicare as the primary payer, were not using an oral anticoagulant, and were newly using an arteriovenous (AV) access for HD. Exposure: AV graft (AVG) or AV fistula (AVF). Outcomes: Major bleeding, venous thromboembolism, ischemic stroke, myocardial infarction, cardiovascular death, and critical limb ischemia. Analytical Approach: Comparing 17,763 AVG and 60,329 AVF users, we estimated the 3-year incidence rates and incidence rate ratios (IRRs) of each outcome using Poisson regression. IRRs were adjusted for sociodemographic and clinical covariates. Results: The use of an AVG, compared with that of an AVF, was associated with an increased risk of venous thromboembolism (10.8 vs 5.3 events per 100 person-years; adjusted IRR, 1.74; 95% CI, 1.63-1.85) but not with the risk of major bleeding (IRR, 1.04; 95% CI, 0.93-1.17). The use of an AVG was also potentially associated with a slightly increased risk of cardiovascular death (IRR, 1.09; 95% CI, 1.01-1.16). Limitations: This analysis focused on patients with a functioning AV access; adverse events that may occur during access maturation should also be considered when selecting a vascular access. Conclusions: The use of an AVG, relative to an AVF, in HD is associated with an increased risk of venous thromboembolism. Given recent guidelines emphasizing selection of the "right access" for the "right patient," the results of this study should potentially be considered as one additional factor when selecting the optimal access for HD.

Apixaban Dosing Patterns Versus Warfarin in Patients With Nonvalvular Atrial Fibrillation Receiving Dialysis: A Retrospective Cohort Study.

BACKGROUND & OBJECTIVES: Comparison of clinical outcomes across anticoagulation regimens using different apixaban dosing or warfarin is not well-defined in patients with nonvalvular atrial fibrillation (AF) who are receiving dialysis. This study compared these outcomes in a US national cohort of patients with kidney failure receiving maintenance dialysis. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: Patients receiving dialysis represented in the US Renal Data System database 2013-2018 who had AF and were treated with apixaban or warfarin. EXPOSURE: First prescribed treatment with apixaban dosed according to the label, apixaban dosed below the label, or warfarin. OUTCOME: Ischemic stroke/systemic embolism, major bleeding, and all-cause mortality. ANALYTICAL APPROACH: Cox proportional hazards models with inverse probability of treatment weighting. Analyses simulating an intention-to-treat (ITT) approach as well as those incorporating censoring at drug switch or discontinuation (CAS) were also implemented. Inverse probability of censoring weighting was used to account for possible informative censoring. RESULTS: Among 17,156 individuals, there was no difference in risk of stroke/systemic embolism among the label-concordant apixaban, below-label apixaban, and warfarin treatment groups. Both label-concordant (HR, 0.67 [95% CI, 0.55-0.81]) and below-label (HR, 0.68 [95% CI, 0.55-0.84]) apixaban dosing were associated with a lower risk of major bleeding compared with warfarin in ITT analyses. Compared with label-concordant apixaban, below-label apixaban was not associated with a lower bleeding risk (HR, 1.02 [95% CI, 0.78-1.34]). In the ITT analysis of mortality, label-concordant apixaban dosing was associated with a lower risk versus warfarin (HR, 0.85 [95% CI, 0.78-0.92]) while there was no significant difference in mortality between below-label dosing of apixaban and warfarin (HR, 0.97 [95% CI, 0.89-1.05]). Overall, results were similar for the CAS analyses. LIMITATIONS: Study limited to US Medicare beneficiaries; reliance on administrative claims to ascertain outcomes of AF, stroke, and bleeding; likely residual confounding. CONCLUSIONS: Among patients with nonvalvular AF undergoing dialysis, warfarin is associated with an increased risk of bleeding compared with apixaban. The risk of bleeding with below-label apixaban was not detectably less than with label-concordant dosing. Label-concordant apixaban dosing is associated with a mortality benefit compared to warfarin. Label-concordant dosing, rather than reduced-label dosing, may offer the most favorable benefit-risk trade-off for dialysis patients with nonvalvular AF.

Apixaban versus Warfarin for Treatment of Venous Thromboembolism in Patients Receiving Long-Term Dialysis.

BACKGROUND AND OBJECTIVES: The association of apixaban compared with warfarin for the treatment of venous thromboembolism in patients receiving maintenance dialysis is not well studied. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted a retrospective cohort study of Medicare fee-for-service beneficiaries receiving dialysis using United States Renal Data System data from 2013 to 2018. The study included patients who received a new prescription for apixaban or warfarin following a venous thromboembolism diagnosis. The outcomes were recurrent venous thromboembolism, major bleeding, and death. Outcomes were analyzed using Cox proportional hazards regression for intention-to-treat and censored-at-drug-switch-or-discontinuation analyses. Models incorporated inverse probability of treatment and censoring weights to minimize confounding and informative censoring. RESULTS: In 12,206 individuals, apixaban, compared with warfarin, was associated with lower risks of both recurrent venous thromboembolism (hazard ratio [HR], 0.58; 95% confidence interval [95% CI], 0.43 to 0.77) and major bleeding (HR, 0.78; 95% CI, 0.62 to 0.98) in the intention-to-treat analysis over 6 months of follow-up. However, there was no difference between apixaban and warfarin in terms of risk of all-cause death (HR, 1.04; 95% CI, 0.94 to 1.16). Corresponding hazard ratios for the 6-month censored-at-drug-switch-or-discontinuation analysis and for corresponding analyses limited to a shorter (3-month) follow-up were all highly similar to the primary analysis. CONCLUSIONS: In a large group of US patients on dialysis with recent venous thromboembolism, we observed that apixaban was associated with lower risk of recurrent venous thromboembolism and of major bleeding than warfarin. There was no observed difference in mortality.

Venous thrombosis risk during and after medical and surgical hospitalizations: The medical inpatient thrombosis and hemostasis (MITH) study.

BACKGROUND: Thirty to seventy percent of all venous thromboembolism (VTE) events are associated with hospitalization. The absolute and relative risks during and after hospitalization are poorly characterized. OBJECTIVES: Quantify the absolute rate and relative risk of VTE during and up to 3 months after medical and surgical hospitalizations. PATIENTS/METHODS: We conducted an observational cohort study between 2010 and 2016 of patients cared for by the University of Vermont (UVM) Health Network's primary care population. Cox proportional hazard models with hospitalization modeled as a time-varying covariate were used to estimate VTE risk. RESULTS: Over 4.3 years of follow-up, 55 220 hospitalizations (156 per 1000 person-years) and 713 first venous thromboembolism events (2.0 per 1000 person-years) occurred. Among individuals not recently hospitalized, the rate of venous thromboembolism was 1.4 per 1000 person-years and 71.8 per 1000 person-years during hospitalization. During the first, second, and third months after discharge, the rates of venous thromboembolism were 35.1, 11.3, and 5.2 per 1000 person-years, respectively. Relative to those not recently hospitalized, the age- and sex-adjusted HRs of venous thromboembolism were 38.0 (95% CI 28.0, 51.5) during hospitalization, and 18.4 (95% CI 15.0, 22.6), 6.3 (95% CI 4.3, 9.0), and 3.0 (95% CI 1.7, 5.4) during the first, second, and third months after discharge, respectively. Stratified by medical versus surgical services the rates were similar. CONCLUSION: Hospitalization and up to 3 months after discharge were strongly associated with increased venous thromboembolism risk. These data quantify this risk for use in future studies.

Comparing Firearm and Stabbing Injuries in the Pediatric Trauma Population Using Propensity Matching.

OBJECTIVES: The objective of this study was to compare differences in mortality and nonhome discharge in pediatric patients with firearm and stab injuries, while minimizing bias. Our secondary objective was to assess the influence of insurance on these same outcomes. METHODS: Patients aged 0 to 17 years included in the National Trauma Data Bank (2007-2015) with firearm and stabbing injury were matched by propensity score. Logistic regression was used to assess associations of injury type and insurance with long-term care discharge and death. RESULTS: The average age was 14.8 years, 19.2% were female, 48% were African American, 58.4% had an injury severity score ≤8, and assaults accounted for 73.1% of cases. Firearm injuries were associated with a higher risk of discharge to long-term care (adjusted odds ratio [aOR], 2.07) compared with propensity-matched patients who were stabbed. Similarly, we found a higher risk of mortality in those with firearm injuries compared with stabbing injuries (aOR, 1.85). Regardless of mechanism, self-pay insurance status was associated with a higher risk of mortality (aOR, 2.41). When compared with stab wound patients with commercial insurance, self-pay firearm-injured patients were found to have an increased risk of mortality (aOR, 5.25). CONCLUSIONS: Pediatric victims of firearm violence were more likely to die or need additional care outside the home than victims of other types of penetrating injury when accounting for confounding characteristics to minimize bias.

Testing Patterns for CKD-MBD Abnormalities in a Sample US Population.

INTRODUCTION: Patterns of testing, treatment, and retesting following treatment for disorders of chronic kidney disease mineral bone disorder (CKD-MBD) have not been explored using a large electronic database. METHODS: To determine concordance with CKD-MBD management guidelines, we used 2010 to 2019 data from an electronic health record (>50 million patients) to create cohorts of incident CKD stage 3, 4, and 5 patients using diagnosis codes and estimated glomerular filtration rates. The CKD-MBD test ordering and relevant drug prescribing were assessed during follow-up. We estimated cumulative incidence of posttreatment retesting (death as competing risk). We used multivariable Cox regression to examine baseline characteristics and pretreatment test results as predictors of retesting. RESULTS: For 215,553 stage 3, 43,576 stage 4, and 11,407 stage 5 CKD patients, the mean follow-up was 2.3, 1.7, and 0.6 years, respectively. Only 46% of stage 4 and 41% of stage 5 patients underwent parathyroid hormone (PTH) testing, 74% and 73% had phosphorus testing, and 38% and 25% had 25D testing. By 1 year after vitamin D sterol treatment, only 50%, 53%, and 60% of stage 3, 4, and 5 patients had been retested for PTH. By 1 year after treatment with ergocalciferol or cholecalciferol, only 46%, 49%, and 55% had 25D reassessed. Pretreatment levels of PTH and 25D were not associated in a graded fashion with likelihood of retesting after treatment. Rates of retesting were not highest for patients with the highest and lowest pre-treatment PTH and 25D levels, respectively. CONCLUSION: Frequency of testing for CKD-MBD abnormalities and posttreatment retesting appears to be suboptimal.