Minimum Distance Matched Sampling With Fine Balance in an Observational Study of Treatment for Ovarian Cancer

How well can fine balance work for covariate balancing

Fine balance is a matching technique to improve covariate balance in observational studies. It constrains a match to have identical distributions for some covariates without restricting who is matched to whom. However, despite its wide application and excellent performance in practice, there is very little theory indicating when the method is likely to succeed or fail and to what extent it can remove covariate imbalance. In order to answer these questions, this paper studies the limits of what is possible for covariate balancing using fine balance and near-fine balance. The investigations suggest that given the distributions of the treated and control groups, in large samples, the maximum achievable balance by using fine balance only depends on the matching ratio (ie, the ratio of the sample size of the control group to that of the treated group). In addition, the results indicate how to estimate this matching ratio threshold without knowledge of the true distributions in finite samples. The findings are also illustrated by numerical studies in this paper.

An overview of propensity score matching methods for clustered data

Propensity score matching is commonly used in observational studies to control for confounding and estimate the causal effects of a treatment or exposure. Frequently, in observational studies data are clustered, which adds to the complexity of using propensity score techniques. In this article, we give an overview of propensity score matching methods for clustered data, and highlight how propensity score matching can be used to account for not just measured confounders, but also unmeasured cluster level confounders. We also consider using machine learning methods such as generalized boosted models to estimate the propensity score and show that accounting for clustering when using these methods can greatly reduce the performance, particularly when there are a large number of clusters and a small number of subjects per cluster. In order to get around this we highlight scenarios where it may be possible to control for measured covariates using propensity score matching, while using fixed effects regression in the outcome model to control for cluster level covariates. Using simulation studies we compare the performance of different propensity score matching methods for clustered data across a number of different settings. Finally, as an illustrative example we apply propensity score matching methods for clustered data to study the causal effect of aspirin on hearing deterioration using data from the conservation of hearing study.

Examining sources of post-acute care inequities with layered target matching

OBJECTIVE

To examine factors associated with racial inequities in discharge location, skilled nursing facility (SNF) utilization, and readmissions.

DATA SOURCES

A 20% sample of longitudinal Medicare claims from 2016 to 2018.

STUDY DESIGN

We present layered target matching, a method for studying sources of inequities. Layered target matching examines a fixed target population profile representing any race, ethnicity, or vulnerable population, sequentially adjusting for sets of characteristics that may contribute to inequities these groups endure. We use the method to study racial inequities in post-acute care use and readmissions.

DATA COLLECTION/EXTRACTION METHODS

We studied Black and non-Hispanic White fee-for-service Medicare beneficiaries aged 66+ admitted to short-term acute-care hospitals for qualifying diagnoses or procedures between January 1, 2016 and November 30, 2018.

PRINCIPAL FINDINGS

Admitted Black patients tended to be younger, had significantly higher rates of risk factors such as diabetes, stroke, or renal disease, and were much more frequently admitted to large or academic hospitals. Relative to demographically similar White patients, Black patients were significantly more likely to be discharged to SNFs (21.8% vs. 19.3%, difference = 2.5%, p < 0.0001) and to receive any SNF care within 30 days of discharge (25.3% vs. 22.4%, difference = 2.9%, p < 0.0001). Black patients were also significantly more likely to experience 30-day readmission (18.7% vs. 14.5%, difference = 4.2%, p < 0.0001). Differences in reasons for hospitalization and risk factors explained most of the differences in discharge location, post-acute care use, and readmission rates, while additional adjustment for differences in hospital characteristics and complications made little difference for any of the measures studied.

CONCLUSIONS

We found significant Black-White differences in discharge to SNFs, SNF utilization, and readmission rates. Using layered target matching, we found that differences in risk factors and reasons for hospitalization explained most of these differences, while differences in hospitals did not materially impact the differences.

Testing Biased Randomization Assumptions and Quantifying Imperfect Matching and Residual Confounding in Matched Observational Studies

One central goal of design of observational studies is to embed non-experimental data into an approximate randomized controlled trial using statistical matching. Despite empirical researchers' best intention and effort to create high-quality matched samples, residual imbalance due to observed covariates not being well matched often persists. Although statistical tests have been developed to test the randomization assumption and its implications, few provide a means to quantify the level of residual confounding due to observed covariates not being well matched in matched samples. In this article, we develop two generic classes of exact statistical tests for a biased randomization assumption. One important by-product of our testing framework is a quantity called residual sensitivity value (RSV), which provides a means to quantify the level of residual confounding due to imperfect matching of observed covariates in a matched sample. We advocate taking into account RSV in the downstream primary analysis. The proposed methodology is illustrated by re-examining a famous observational study concerning the effect of right heart catheterization (RHC) in the initial care of critically ill patients. Code implementing the method can be found in the supplementary materials.

Association of Intraoperative Transesophageal Echocardiography and Clinical Outcomes After Open Cardiac Valve or Proximal Aortic Surgery

IMPORTANCE

Intraoperative transesophageal echocardiography (TEE) is used frequently in cardiac valve and proximal aortic surgical procedures, but there is a lack of evidence associating TEE use with improved clinical outcomes.

OBJECTIVE

To test the association between intraoperative TEE use and clinical outcomes following cardiac valve or proximal aortic surgery.

DESIGN, SETTING, AND PARTICIPANTS

This matched, retrospective cohort study used national registry data from the Society of Thoracic Surgeon (STS) Adult Cardiac Surgery Database (ACSD) to compare clinical outcomes among patients undergoing cardiac valve or proximal aortic surgery with vs without intraoperative TEE. Statistical analyses used optimal matching within propensity score calipers to conduct multiple matched comparisons including within-hospital and within-surgeon matches, a negative control outcome analysis, and sensitivity analyses. STS ACSD data encompasses more than 90% of all hospitals that perform cardiac surgery in the US. The study cohort consisted of all patients aged at least 18 years undergoing open cardiac valve repair or replacement surgery and/or proximal aortic surgery between 2011 and 2019. Statistical analysis was performed from October 2020 to April 2021.

EXPOSURES

The exposure was receipt of intraoperative TEE during the cardiac valve or proximal aortic surgery.

MAIN OUTCOMES AND MEASURES

The primary outcome was death within 30 days of surgery. The secondary outcomes were (1) a composite outcome of stroke or 30-day mortality and (2) a composite outcome of reoperation or 30-day mortality.

RESULTS

Of the 872 936 patients undergoing valve or aortic surgery, 540 229 (61.89%) were male; 63 565 (7.28%) were Black and 742 384 (85.04%) were White; 711 326 (81.5%) received TEE and 161 610 (18.5%) did not receive TEE; the mean (SD) age was 65.61 years (13.17) years. After matching, intraoperative TEE was significantly associated with a lower 30-day mortality rate compared with no TEE: 3.81% vs 5.27% (odds ratio [OR], 0.69 [95% CI, 0.67-0.72]; P < .001), a lower incidence of stroke or 30-day mortality: 5.56% vs 7.01% (OR, 0.77 [95% CI, 0.74-0.79]; P < .001), and a lower incidence of reoperation or 30-day mortality: 7.18% vs 8.87% (OR, 0.78 [95% CI, 0.76-0.80]; P < .001). Results were similar across all matched comparisons (including within-hospital, within-surgeon matched analyses) and were robust to a negative control and sensitivity analyses.

CONCLUSIONS AND RELEVANCE

Among adults undergoing cardiac valve or proximal aortic surgery, intraoperative TEE use was associated with improved clinical outcomes in this cohort study. These findings support routine use of TEE in these procedures.

Core concepts in pharmacoepidemiology: Violations of the positivity assumption in the causal analysis of observational data: Consequences and statistical approaches

In the causal analysis of observational data, the positivity assumption requires that all treatments of interest be observed in every patient subgroup. Violations of this assumption are indicated by nonoverlap in the data in the sense that patients with certain covariate combinations are not observed to receive a treatment of interest, which may arise from contraindications to treatment or small sample size. In this paper, we emphasize the importance and implications of this often-overlooked assumption. Further, we elaborate on the challenges nonoverlap poses to estimation and inference and discuss previously proposed methods. We distinguish between structural and practical violations and provide insight into which methods are appropriate for each. To demonstrate alternative approaches and relevant considerations (including how overlap is defined and the target population to which results may be generalized) when addressing positivity violations, we employ an electronic health record-derived data set to assess the effects of metformin on colon cancer recurrence among diabetic patients.

Estimation of causal effect in integrating randomized clinical trial and observational data - An example application to cardiovascular outcome trial

Safety evaluation of drug development is a comprehensive process across the product lifecycle. While a randomized clinical trial (RCT) can provide high-quality data to assess the efficacy and safety of a new intervention, the pre-marketing trials are limited in statistical power to detect causal elevation of rare but potentially serious adverse events. On the other hand, real-world data (RWD) sources play a critical role in further understanding the safety profile of the new intervention. Bringing together the breadth and strength of RWD and RCT data, we can maximize the utility of RWD and answer broader questions. In this manuscript, we propose a three-step statistical framework to corroborate findings from both RCT and RWD for evaluating important safety concerns identified in the pre-marketing setting. By the proposed approach, we first match the observational study to RCT, then the causal estimation is validated via the matched observational study with the target RCT by targeted maximum likelihood estimation (TMLE) method, and lastly the evidence from RCT and RWD can be combined in an integrative analysis. A potential application to cardiovascular outcome trials for type 2 diabetes mellitus is illustrated. Finally, simulation results suggest that the heterogeneity of patient population from RCT and RWD can lead to varying degrees of treatment effect estimation and the proposed approach may be able to mitigate such difference in the integrative analysis.

Multi-agent neoadjuvant chemotherapy improves survival in early-stage pancreatic cancer: A National Cancer Database analysis

PURPOSE

To compare overall survival (OS) in patients who underwent surgery for early-stage pancreatic adenocarcinoma (rPca) based on sequence (NAT, neoadjuvant therapy and/or AT, adjuvant therapy) and type (SA, single-agent or MA, multi-agent) of chemotherapy received.

METHODS

Using the National Cancer Database, patients with clinical stage I/II rPca diagnosed between 2010 and 2014 were identified and five comparison matches (1: NAT vs. upfront resection (UR); 2: multi-agent neoadjuvant (MA NAT) vs. single-agent adjuvant therapy (SA AT), single-agent neoadjuvant therapy (SA NAT), multi-agent adjuvant therapy (MA AT); 3: MA NAT vs. MA AT; 4: NAT + AT vs NAT; 5: NAT + AT vs AT) were constructed using minimum distance matching strategy. Median OS (mOS) was analysed using Kaplan-Meier method, log-rank test and Cox proportional hazard model.

RESULTS

A total of 18,470 patients with stage I/II rPca were eligible for analysis. NAT showed a 5 month (mo.) improved OS compared with UR (3271 patients/group, 28.1 vs 23.2 mo. P < 0.0001 hazard ratio [HR]: 0.79). MA-NAT was shown to be superior to other chemotherapy approaches SA AT, SA NAT, and MA AT (1349 patients/group: 30 vs. 25.9 mo., P = 0.0001 [HR: 0.82]). MA NAT showed a survival advantage over MA-AT (1349 patients/group, 30 vs 26.1 mo., P = 0.0008 [HR: 0.86]). The combination of NAT and AT showed a better outcome when compared with NAT alone (1128 patients/group, 31.6 vs 27.4 mo., P = 0.0011 [HR: 0.81]) or AT alone (1128 patients/group, 31.6 vs. 25.2 mo., P < 0.0001 [HR: 0.76]).

CONCLUSIONS

In patients with stage I/II rPca, MA NAT showed improved mOS compared to UR and all other chemotherapy sequences except both NAT plus AT. These findings support the use of MA NAT in stage I/II rPca patients and warrant prospective trials evaluating MA NAT and post-resection maintenance therapies.

Impact of COVID-19 Restrictions on Demographics and Outcomes of Patients Undergoing Medically Necessary Non-Emergent Surgeries During the Pandemic

Background

The COVID-19 pandemic has resulted in large-scale healthcare restrictions to control viral spread, reducing operating room censuses to include only medically necessary surgeries. The impact of restrictions on which patients undergo surgical procedures and their perioperative outcomes is less understood.

Methods

Adult patients who underwent medically necessary surgical procedures at our institution during a restricted operative period due to the COVID-19 pandemic (March 23-April 24, 2020) were compared to patients undergoing procedures during a similar time period in the pre-COVID-19 era (March 25-April 26, 2019). Cardinal matching and differences in means were utilized to analyze perioperative outcomes.

Results

857 patients had surgery in 2019 (pre-COVID-19) and 212 patients had surgery in 2020 (COVID-19). The COVID-19 era cohort had a higher proportion of patients who were male (61.3% vs. 44.5%, P < 0.0001), were White (83.5% vs. 68.7%, P < 0.001), had private insurance (62.7% vs. 54.3%, p 0.05), were ASA classification 4 (10.9% vs. 3%, P < 0.0001), and underwent oncologic procedures (69.3% vs. 42.7%, P < 0.0001). Following 1:1 cardinal matching, COVID-19 era patients (N = 157) had a decreased likelihood of discharge to a nursing facility (risk difference-8.3, P < 0.0001) and shorter median length of stay (risk difference-0.6, p 0.04) compared to pre-COVID-19 era patients. There was no difference between the two patient cohorts in overall morbidity and 30-day readmission.

Conclusions

COVID-19 restrictions on surgical operations were associated with a change in the racial and insurance demographics in patients undergoing medically necessary surgical procedures but were not associated with worse postoperative morbidity. Further study is necessary to better identify the causes for patient demographic differences.

Supplementary Information

The online version contains supplementary material available at (10.1007/s00268-021-05958-z).

Evaluating the Costs and Outcomes of Hospital Nursing Resources: a Matched Cohort Study of Patients with Common Medical Conditions

BACKGROUND

Nursing resources, such as staffing ratios and skill mix, vary across hospitals. Better nursing resources have been linked to better patient outcomes but are assumed to increase costs. The value of investments in nursing resources, in terms of clinical benefits relative to costs, is unclear.

OBJECTIVE

To determine whether there are differential clinical outcomes, costs, and value among medical patients at hospitals characterized by better or worse nursing resources.

DESIGN

Matched cohort study of patients in 306 acute care hospitals.

PATIENTS

A total of 74,045 matched pairs of fee-for-service Medicare beneficiaries admitted for common medical conditions (25,446 sepsis pairs; 16,332 congestive heart failure pairs; 12,811 pneumonia pairs; 10,598 stroke pairs; 8858 acute myocardial infarction pairs). Patients were also matched on hospital size, technology, and teaching status.

MAIN MEASURES

Better (n = 76) and worse (n = 230) nursing resourced hospitals were defined by patient-to-nurse ratios, skill mix, proportions of bachelors-degree nurses, and nurse work environments. Outcomes included 30-day mortality, readmission, and resource utilization-based costs.

KEY RESULTS

Patients in hospitals with better nursing resources had significantly lower 30-day mortality (16.1% vs 17.1%, p < 0.0001) and fewer readmissions (32.3% vs 33.6%, p < 0.0001) yet costs were not significantly different ($18,848 vs 18,671, p = 0.133). The greatest outcomes and cost advantage of better nursing resourced hospitals were in patients with sepsis who had lower mortality (25.3% vs 27.6%, p < 0.0001). Overall, patients with the highest risk of mortality on admission experienced the greatest reductions in mortality and readmission from better nursing at no difference in cost.

CONCLUSIONS

Medicare beneficiaries with common medical conditions admitted to hospitals with better nursing resources experienced more favorable outcomes at almost no difference in cost.

Patients With a History of a Cardiac Implantable Electronic Device Have a Higher Likelihood of 90-Day Cardiac Events After Total Joint Arthroplasty: A Matched Cohort Study

INTRODUCTION

We sought to identify the incidence of new 90-day cardiac events, 90-day mortality, 90-day unplanned readmissions, and 30-day emergency department (ED) visits after total joint arthroplasty (TJA) in patients with a history of a cardiac implantable electronic device (CIED) and compare these outcomes in TJA patients without a CIED.

METHODS

Kaiser Permanente's Cardiac Device and Total Joint Replacement Registries were used to identify elective primary TJA performed for osteoarthritis. TJA with a CIED was matched with TJA without a CIED (n = 365 pairs) on patient characteristics, demographics, and procedure type. A McNemar test was used to evaluate categorical outcomes.

RESULTS

Of the TJA with a CIED, there were 24 cardiac events (6.6%), 1 mortality (0.3%), 30 readmissions (8.2%), and 39 ED visits (10.7%). TJA patients with a CIED had a higher likelihood of cardiac events (odds ratio [OR] = 3.14, 95% confidence interval [CI] = 1.28 to 8.08). No difference was observed in mortality (OR = 0.50, 95% CI = 0.02 to 6.98), readmissions (OR = 1.26, 95% CI = 0.71 to 2.25), or ED visits (OR = 1.15, 95% CI = 0.71 to 1.88).

CONCLUSION

In our matched cohort study, TJA patients with a history of a CIED had a higher likelihood of incident 90-day cardiac events when compared with patients without a CIED without a difference observed for 90-day mortality, unplanned readmission, and 30-day ED visit.

LEVEL OF EVIDENCE

Level III.

Developing a template matching algorithm for benchmarking hospital performance in a diverse, integrated healthcare system

Template matching is a proposed approach for hospital benchmarking, which measures performance based on matching a subset of comparable patient hospitalizations from each hospital. We assessed the ability to create the required matched samples and thus the feasibility of template matching to benchmark hospital performance in a diverse healthcare system.Nationwide Veterans Affairs (VA) hospitals, 2017.Observational cohort study.We used administrative and clinical data from 668,592 hospitalizations at 134 VA hospitals in 2017. A standardized template of 300 hospitalizations was selected, and then 300 hospitalizations were matched to the template from each hospital.There was substantial case-mix variation across VA hospitals, which persisted after excluding small hospitals, hospitals with primarily psychiatric admissions, and hospitalizations for rare diagnoses. Median age ranged from 57 to 75 years across hospitals; percent surgical admissions ranged from 0.0% to 21.0%; percent of admissions through the emergency department, 0.1% to 98.7%; and percent Hispanic patients, 0.2% to 93.3%. Characteristics for which there was substantial variation across hospitals could not be balanced with any matching algorithm tested. Although most other variables could be balanced, we were unable to identify a matching algorithm that balanced more than ∼20 variables simultaneously.We were unable to identify a template matching approach that could balance hospitals on all measured characteristics potentially important to benchmarking. Given the magnitude of case-mix variation across VA hospitals, a single template is likely not feasible for general hospital benchmarking.

Infections Associated with Resterilized Pacemakers and Defibrillators

BACKGROUND

Access to pacemakers and defibrillators is problematic in places with limited resources. Resterilization and reuse of implantable cardiac devices obtained post mortem from patients in wealthier nations have been undertaken, but uncertainty around the risk of infection is a concern.

METHODS

A multinational program was initiated in 1983 to provide tested and resterilized pacemakers and defibrillators to underserved nations; a prospective registry was established in 2003. Patients who received reused devices in this program were matched in a 1:3 ratio with control patients who received new devices implanted in Canada. The primary outcome was infection or device-related death, with mortality from other causes modeled as a competing risk.

RESULTS

Resterilized devices were implanted in 1051 patients (mean [±SD] age, 63.2±18.5 years; 43.6% women) in Mexico (36.0%), the Dominican Republic (28.1%), Guatemala (26.6%), and Honduras (9.3%). Overall, 85% received pacemakers and 15% received defibrillators, with one (55.5%), two (38.8%), or three (5.7%) leads. Baseline characteristics did not differ between these patients and the 3153 matched control patients. At 2 years of follow-up, infections had occurred in 21 patients (2.0%) with reused devices and in 38 (1.2%) with new devices (hazard ratio, 1.66; 95% confidence interval, 0.97 to 2.83; P = 0.06); there were no device-related deaths. The most common implicated pathogens were Staphylococcus aureus and S. epidermidis.

CONCLUSIONS

Among patients in underserved countries who received a resterilized and reused pacemaker or defibrillator, the incidence of infection or device-related death at 2 years was 2.0%, an incidence that did not differ significantly from that seen among matched control patients with new devices in Canada.

Valuing hospital investments in nursing: multistate matched-cohort study of surgical patients

BACKGROUND

There are known clinical benefits associated with investments in nursing. Less is known about their value.

AIMS

To compare surgical patient outcomes and costs in hospitals with better versus worse nursing resources and to determine if value differs across these hospitals for patients with different mortality risks.

METHODS

Retrospective matched-cohort design of patient outcomes at hospitals with better versus worse nursing resources, defined by patient-to-nurse ratios, skill mix, proportions of bachelors-degree nurses and nurse work environments. The sample included 62 715 pairs of surgical patients in 76 better nursing resourced hospitals and 230 worse nursing resourced hospitals from 2013 to 2015. Patients were exactly matched on principal procedures and their hospital's size category, teaching and technology status, and were closely matched on comorbidities and other risk factors.

RESULTS

Patients in hospitals with better nursing resources had lower 30-day mortality: 2.7% vs 3.1% (p<0.001), lower failure-to-rescue: 5.4% vs 6.2% (p<0.001), lower readmissions: 12.6% vs 13.5% (p<0.001), shorter lengths of stay: 4.70 days vs 4.76 days (p<0.001), more intensive care unit admissions: 17.2% vs 15.4% (p<0.001) and marginally higher nurse-adjusted costs (which account for the costs of better nursing resources): $20 096 vs $19 358 (p<0.001), as compared with patients in worse nursing resourced hospitals. The nurse-adjusted cost associated with a 1% improvement in mortality at better nursing hospitals was $2035. Patients with the highest mortality risk realised the greatest value from nursing resources.

CONCLUSION

Hospitals with better nursing resources provided better clinical outcomes for surgical patients at a small additional cost. Generally, the sicker the patient, the greater the value at better nursing resourced hospitals.

The Association Between Tibial Slope and Revision Anterior Cruciate Ligament Reconstruction in Patients ≤21 Years Old: A Matched Case-Control Study Including 317 Revisions

BACKGROUND

There is evidence that tibial slope may play a role in revision risk after anterior cruciate ligament reconstruction (ACLR); however, prior studies are inconsistent.

PURPOSE

To determine (1) whether there is a difference in lateral tibial posterior slope (LTPS) or medial tibial posterior slope (MTPS) between patients undergoing revised ACLR and those not requiring revision and (2) whether the medial-to-lateral slope difference is different between these 2 groups.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

We conducted a matched case-control study (2006-2015). Cases were patients aged ≤21 years who underwent revision surgery after primary unilateral ACLR; controls were patients aged ≤21 years without revision who were identified from the same source population. Controls were matched to cases by age, sex, body mass index, race, graft type, femoral fixation device, and post-ACLR follow-up time. Tibial slope measurements were made by a single blinded reviewer using magnetic resonance imaging. The Wilcoxon signed rank test and McNemar test were used for continuous and categorical variables, respectively.

RESULTS

No difference was observed between revised and nonrevised ACLR groups for LTPS (median: 6° vs 6°, P = .973) or MTPS (median: 4° vs 5°, P = .281). Furthermore, no difference was found for medial-to-lateral slope difference (median: -1 vs -1, P = .289). A greater proportion of patients with revised ACLR had an LTPS ≥12° (7.6% vs 3.8%) and ≥13° (4.7% vs 1.3%); however, this was not statistically significant after accounting for multiple testing.

CONCLUSION

We failed to observe an association between revision ACLR surgery and LTPS, MTPS, or medial-to-lateral slope difference. However, there was a greater proportion of patients in the revision ACLR group with an LTPS ≥12°, suggesting that a minority of patients who have more extreme values of LTPS have a higher revision risk after primary ACLR. A future cohort study evaluating the angle that best differentiates patients at highest risk for revision is needed.

National Trends in Utilization and 1-Year Outcomes with Transplantation of HCV-Viremic Kidneys

BACKGROUND

Recent pilot trials have demonstrated the safety of transplanting HCV-viremic kidneys into HCV-seronegative recipients. However, it remains unclear if allograft function is impacted by donor HCV-viremia or recipient HCV-serostatus.

METHODS

We used national United States registry data to examine trends in HCV-viremic kidney use between 4/1/2015 and 3/31/2019. We applied advanced matching methods to compare eGFR for similar kidneys transplanted into highly similar recipients of kidney transplants.

RESULTS

Over time, HCV-seronegative recipients received a rising proportion of HCV-viremic kidneys. During the first quarter of 2019, 200 HCV-viremic kidneys were transplanted into HCV-seronegative recipients, versus 69 into HCV-seropositive recipients, while 105 HCV-viremic kidneys were discarded. The probability of HCV-viremic kidney discard has declined over time. Kidney transplant candidates willing to accept a HCV-seropositive kidney increased from 2936 to 16,809 from during this time period. When transplanted into HCV-seronegative recipients, HCV-viremic kidneys matched to HCV-non-viremic kidneys on predictors of organ quality, except HCV, had similar 1-year eGFR (66.3 versus 67.1 ml/min per 1.73 m², P=0.86). This was despite the much worse kidney donor profile index scores assigned to the HCV-viremic kidneys. Recipient HCV-serostatus was not associated with a clinically meaningful difference in 1-year eGFR (66.5 versus 71.1 ml/min per 1.73 m², P=0.056) after transplantation of HCV-viremic kidneys.

CONCLUSIONS

By 2019, HCV-seronegative patients received the majority of kidneys transplanted from HCV-viremic donors. Widely used organ quality scores underestimated the quality of HCV-viremic kidneys based on 1-year allograft function. Recipient HCV-serostatus was also not associated with worse short-term allograft function using HCV-viremic kidneys.

Comparing Resource Use in Medical Admissions of Children With Complex Chronic Conditions

BACKGROUND

Children with complex chronic conditions (CCCs) utilize a disproportionate share of hospital resources.

OBJECTIVE

We asked whether some hospitals display a significantly different pattern of resource utilization than others when caring for similar children with CCCs admitted for medical diagnoses.

RESEARCH DESIGN

Using Pediatric Health Information System data from 2009 to 2013, we constructed an inpatient Template of 300 children with CCCs, matching these to 300 patients at each hospital, thereby performing a type of direct standardization.

SUBJECTS

Children with CCCs were drawn from a list of the 40 most common medical principal diagnoses, then matched to patients across 40 Children's Hospitals.

MEASURES

Rate of intensive care unit admission, length of stay, resource cost.

RESULTS

For the Template-matched patients, when comparing resource use at the lower 12.5-percentile and upper 87.5-percentile of hospitals, we found: intensive care unit utilization was 111% higher (6.6% vs. 13.9%, P<0.001); hospital length of stay was 25% higher (2.4 vs. 3.0 d/admission, P<0.001); and finally, total cost per patient varied by 47% ($6856 vs. $10,047, P<0.001). Furthermore, some hospitals, compared with their peers, were more efficient with low-risk patients and less efficient with high-risk patients, whereas other hospitals displayed the opposite pattern.

CONCLUSIONS

Hospitals treating similar patients with CCCs admitted for similar medical diagnoses, varied greatly in resource utilization. Template Matching can aid chief quality officers benchmarking their hospitals to peer institutions and can help determine types of their patients having the most aberrant outcomes, facilitating quality initiatives to target these patients.

Ascorbic Acid, Thiamine, and Steroids in Septic Shock: Propensity Matched Analysis

INTRODUCTION

We aimed to study the use of ascorbic acid, thiamine, and steroids (ATS) in patients with septic shock (SS).

METHODS

Data on 62 patients with SS were collected from Acute Physiologic and Chronic Health Evaluation (APACHE) Outcome database and medical records. The ATS group received full doses of intravenous (IV) ATS (ascorbic acid [1.5 g every 6 hours for 4 days], hydrocortisone [50 mg every 6 hours for 7 days], and thiamine [200 mg every 12 hours for 4 days]). Data included age, gender, APACHE III, acute physiologic score (APS), mechanical ventilation (MV), lactic acid (LA), serum creatinine (Cr), duration of vasopressors (VP, days, median: interquartile ranges [IQR]: [Q1, Q3]), MV-free days (median: IQR [Q1-Q3]), percentage of patients requiring renal replacement therapy (RRT) for acute kidney injury (AKI), and mortality. Propensity analysis was used to match patients on age, gender, MV, APACHE III, APS, LA, and Cr.

RESULTS

The ATS group had longer duration of VP (4.5: 4.0-6.0 vs 2.0: 1.0-2.0, P = .001), similar RRT for AKI (26% vs 29%, P = .8), similar MV-free days (10.2: 5.0-15.0 vs 10.2: 1.6-18.0, P > .9), lower intensive care unit mortality (9.6% vs 42%, P = .004), and a trend toward lower hospital mortality (29% vs 45%, P = .2) compared to the NO ATS group.

CONCLUSIONS

The use of IV ascorbic acid, thiamine, and hydrocortisone might be beneficial in patients with SS.

A method to reduce imbalance for site-level randomized stepped wedge implementation trial designs

BACKGROUND

Controlled implementation trials often randomize the intervention at the site level, enrolling relatively few sites (e.g., 6-20) compared to trials that randomize by subject. Trials with few sites carry a substantial risk of an imbalance between intervened (cases) and non-intervened (control) sites in important site characteristics, thereby threatening the internal validity of the primary comparison. A stepped wedge design (SWD) staggers the intervention at sites over a sequence of times or time waves until all sites eventually receive the intervention. We propose a new randomization method, sequential balance, to control time trend in site allocation by minimizing sequential imbalance across multiple characteristics. We illustrate the new method by applying it to a SWD implementation trial.

METHODS

The trial investigated the impact of blended internal-external facilitation on the establishment of evidence-based teams in general mental health clinics in nine US Department of Veterans Affairs medical centers. Prior to randomization to start time, an expert panel of implementation researchers and health system program leaders identified by consensus a series of eight facility-level characteristics judged relevant to the success of implementation. We characterized each of the nine sites according to these consensus features. Using a weighted sum of these characteristics, we calculated imbalance scores for each of 1680 possible site assignments to identify the most sequentially balanced assignment schemes.

RESULTS

From 1680 possible site assignments, we identified 34 assignments with minimal imbalance scores, and then randomly selected one assignment by which to randomize start time. Initially, the mean imbalance score was 3.10, but restricted to the 34 assignments, it declined to 0.99.

CONCLUSIONS

Sequential balancing of site characteristics across groups of sites in the time waves of a SWD strengthens the internal validity of study conclusions by minimizing potential confounding.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov as clinical trials # NCT02543840 ; entered 9/4/2015.

Multiple listing in lung transplant candidates: A cohort study

Lung transplant candidates can be waitlisted at more than one transplant center, a practice known as multiple listing. The factors associated with multiple listing and whether multiple listing modifies waitlist mortality or likelihood of lung transplant is unknown. US lung transplant waitlist candidates were identified as either single or multiple listed using data from the Scientific Registry of Transplant Recipients. Characteristics of single and multiple listed candidates were compared and multivariable logistic regression was used to estimate associations with multiple listing. Multiple listed candidates were matched to single listed candidates using a combination of exact and propensity score matching methods. Cox proportional hazard models were used to estimate the relationship of multiple listing on waitlist mortality and receiving a transplant. Multiple listing occurred in 2.3% of lung transplant waitlist candidates. Younger age, female gender, white race, short stature, high antibody sensitization, college or postcollege education, lower lung allocation score, and a cystic fibrosis diagnosis were independently associated with multiple listing. Multiple listing was associated with an increased likelihood of lung transplant (adjusted hazard ratio [aHR] 2.74, 95% CI 2.37 to 3.16) but was not associated with waitlist mortality (aHR 0.99, 95% CI 0.68 to 1.44).

Practice Style Variation in Medicaid and Non-Medicaid Children With Complex Chronic Conditions Undergoing Surgery

OBJECTIVES

With differential payment between Medicaid and Non-Medicaid services, we asked whether style-of-practice differs between similar Medicaid and Non-Medicaid children with complex chronic conditions (CCCs) undergoing surgery.

SUMMARY OF BACKGROUND DATA

Surgery in children with CCCs accounts for a disproportionately large percentage of resource utilization at major children's hospitals.

METHODS

A matched cohort design, studying 23,582 pairs of children with CCCs undergoing surgery (Medicaid matched to Non-Medicaid within the same hospital) from 2009 to 2013 in 41 Children's Hospitals. Patients were matched on age, sex, principal procedure, CCCs, and other characteristics.

RESULTS

Median cost in Medicaid patients was $21,547 versus $20,527 in Non-Medicaid patients (5.0% higher, P < 0.001). Median paired difference in cost (Medicaid minus Non-Medicaid) was $320 [95% confidence interval (CI): $208, $445], (1.6% higher, P < 0.001). 90th percentile costs were $133,640 versus $127,523, (4.8% higher, P < 0.001). Mean paired difference in length of stay (LOS) was 0.50 days (95% CI: 0.36, 0.65), (P < 0.001). ICU utilization was 2.8% higher (36.7% vs 35.7%, P < 0.001). Finally, in-hospital mortality pooled across all pairs was higher in Medicaid patients (0.38% vs 0.22%, P = 0.002). After adjusting for multiple testing, no individual hospital displayed significant differences in cost between groups, only 1 hospital displayed significant differences in LOS and 1 in ICU utilization.

CONCLUSIONS

Treatment style differences between Medicaid and Non-Medicaid children were small, suggesting little disparity with in-hospital surgical care for patients with CCCs operated on within Children's Hospitals. However, in-hospital mortality, although rare, was slightly higher in Medicaid patients and merits further investigation.

Sequential matched analysis of racial disparities in breast cancer hospitalization outcomes among African American and White patients

BACKGROUND

The purpose of this study is to determine if racial disparities in inpatient outcomes persist among hospitalized patients comparing African American and White breast cancer patients matched on demographics, presentation and treatment.

METHODS

A total of 136,211 African American and White breast cancer patients from the Healthcare Cost and Utilization Project - Nationwide Inpatient Sample (HCUP-NIS) database, matched on demographics alone, demographics and presentation or demographics, presentation and treatment were studied. Conditional logistic regression was conducted to evaluate post-surgical complications, length of stay and in-hospital mortality outcomes. Analysis was further stratified by age (≤65 years and >65years) to evaluate whether disparities were larger in younger or older patients. All analysis was conducted using SAS 9.3.

RESULTS

White women had significantly shorter hospital length of stay when matched on demographics (β=-0.87, p-value=<0.0001), demographics and presentation (β=-0.63, p-value=<0.0001), and demographics, presentation and treatment (β=-0.51, p-value=<0.0001) compared with African Americans. White women also had lower odds of mortality compared with African American women when matched on demographics (OR: 0.72, 95% CI: 0.65-0.79), demographics and presentation (OR: 0.77, 95% CI: 0.71-0.85), or matched on demographics, presentation and treatment (OR: 0.80, 95% CI: 0.73-0.88). The racial difference observed in length of stay and mortality was larger in the age group ≤65 years compared with >65years CONCLUSION: African American women experienced higher odds of inpatient mortality and longer length of stay compared with White women even after accounting for differences in demographics, presentation and treatment characteristics.

Comparing Outcomes between Antibody Induction Therapies in Kidney Transplantation

Kidney transplant recipients often receive antibody induction. Previous studies of induction therapy were often limited by short follow-up and/or absence of information about complications. After linking Organ Procurement and Transplantation Network data with Medicare claims, we compared outcomes between three induction therapies for kidney recipients. Using novel matching techniques developed on the basis of 15 clinical and demographic characteristics, we generated 1:1 pairs of alemtuzumab-rabbit antithymocyte globulin (rATG) (5330 pairs) and basiliximab-rATG (9378 pairs) recipients. We used paired Cox regression to analyze the primary outcomes of death and death or allograft failure. Secondary outcomes included death or sepsis, death or lymphoma, death or melanoma, and healthcare resource utilization within 1 year. Compared with rATG recipients, alemtuzumab recipients had higher risk of death (hazard ratio [HR], 1.14; 95% confidence interval [95% CI], 1.03 to 1.26; P<0.01) and death or allograft failure (HR, 1.18; 95% CI, 1.09 to 1.28; P<0.001). Results for death as well as death or allograft failure were generally consistent among elderly and nonelderly subgroups and among pairs receiving oral prednisone. Compared with rATG recipients, basiliximab recipients had higher risk of death (HR, 1.08; 95% CI, 1.01 to 1.16; P=0.03) and death or lymphoma (HR, 1.12; 95% CI, 1.01 to 1.23; P=0.03), although these differences were not confirmed in subgroup analyses. One-year resource utilization was slightly lower among alemtuzumab recipients than among rATG recipients, but did not differ between basiliximab and rATG recipients. This observational evidence indicates that, compared with alemtuzumab and basiliximab, rATG associates with lower risk of adverse outcomes, including mortality.

Outcomes, ICU Use, and Length of Stay in Chronically Ill Black and White Children on Medicaid and Hospitalized for Surgery

BACKGROUND

With increasing Medicaid coverage, it has become especially important to determine whether racial differences exist within the Medicaid system. We asked whether disparities exist in hospital practice and patient outcomes between matched black and white Medicaid children with chronic conditions undergoing surgery.

STUDY DESIGN

We conducted a matched cohort study, matching 6,398 pairs within states on detailed patient characteristics using data from 25 states contributing adequate Medicaid Analytic eXtract claims for admissions of children with chronic conditions undergoing the same surgical procedures between January 1, 2009 and November 30, 2010 for ages 1 to 18 years.

RESULTS

The black patient 30-day revisit rate was 19.3% vs 19.8% in matched white patients (p = 0.61), 30-day readmission rates were 7.0% vs 6.9% (p = 0.43), and 30-day mortality rates were 0.38% vs 0.19% (p = 0.06), respectively. A higher percentage of black patients exceeded their own state's individual median length of stay (44.0% vs 39.6%; p < 0.001) and median ICU length of stay (25.9% vs 23.8%; p < 0.001). Intensive care unit use was higher in black patients (25.9% vs 23.8%; p < 0.001). After adjusting for multiple testing, only 2 states were found to differ significantly by race (New York for length of stay and New Jersey for ICU use).

CONCLUSIONS

We did not observe disparities in 30-day revisits and readmissions for chronically ill children in Medicaid undergoing surgery, and only slight differences in length of stay, ICU length of stay, and use of the ICU, where blacks displayed somewhat elevated rates compared with white controls.

Racial Disparities in Medicaid Asthma Hospitalizations

BACKGROUND AND OBJECTIVES

Black children with asthma comprise one-third of all asthma patients in Medicaid. With increasing Medicaid coverage, it has become especially important to monitor Medicaid for differences in hospital practice and patient outcomes by race.

METHODS

A multivariate matched cohort design, studying 11 079 matched pairs of children in Medicaid (black versus white matched pairs from inside the same state) admitted for asthma between January 1, 2009 and November 30, 2010 in 33 states contributing adequate Medicaid Analytic eXtract claims.

RESULTS

Ten-day revisit rates were 3.8% in black patients versus 4.2% in white patients (P = .12); 30-day revisit and readmission rates were also not significantly different by race (10.5% in black patients versus 10.8% in white patients; P = .49). Length of stay (LOS) was also similar; both groups had a median stay of 2.0 days, with a slightly lower percentage of black patients exceeding their own state's median LOS (30.2% in black patients versus 31.8% in white patients; P = .01). The mean paired difference in LOS was 0.00 days (95% confidence interval, -0.08 to 0.08). However, ICU use was higher in black patients than white patients (22.2% versus 17.5%; P < .001). After adjusting for multiple testing, only 4 states were found to differ significantly, but only in ICU use, where blacks had higher rates of use.

CONCLUSIONS

For closely matched black and white patients, racial disparities concerning asthma admission outcomes and style of practice are small and generally nonsignificant, except for ICU use, where we observed higher rates in black patients.

Effect of prophylactic CPAP in very low birth weight infants in South America

OBJECTIVE

The objective of this study was to examine the effect of prophylactic continuous positive airway pressure (CPAP) on infants born in 25 South American neonatal intensive care units affiliated with the Neocosur Neonatal Network using novel multivariate matching methods.

STUDY DESIGN

A prospective cohort was constructed of infants with a birth weight 500 to 1500 g born between 2005 and 2011 who clinically were eligible for prophylactic CPAP. Patients who received prophylactic CPAP were matched to those who did not on 23 clinical and sociodemographic variables (N=1268). Outcomes were analyzed using the McNemar's test.

RESULTS

Infants not receiving prophylactic CPAP had higher mortality rates (odds ratio (OR)=1.69, 95% confidence interval (CI) 1.17, 2.46), need for any mechanical ventilation (OR=1.68, 95% CI 1.33, 2.14) and death or bronchopulmonary dysplasia (BPD) (OR=1.47, 95% CI 1.09, 1.98). The benefit of prophylactic CPAP varied by birth weight and gender.

CONCLUSIONS

The implementation of this process was associated with a significant improvement in survival and survival free of BPD.

Practice Patterns in Medicaid and Non-Medicaid Asthma Admissions

BACKGROUND AND OBJECTIVES

With American children experiencing increased Medicaid coverage, it has become especially important to determine if practice patterns differ between Medicaid and non-Medicaid patients. Auditing such potential differences must carefully compare like patients to avoid falsely identifying suspicious practice patterns. We asked if we could observe differences in practice patterns between Medicaid and non-Medicaid patients admitted for asthma inside major children's hospitals.

METHODS

A matched cohort design, studying 17 739 matched pairs of children (Medicaid to non-Medicaid) admitted for asthma in the same hospital between April 1, 2011 and March 31, 2014 in 40 Children's Hospital Association hospitals contributing data to the Pediatric Hospital Information System database. Patients were matched on age, sex, asthma severity, and other patient characteristics.

RESULTS

Medicaid patient median cost was $4263 versus $4160 for non-Medicaid patients (P < .001). Additionally, the median cost difference (Medicaid minus non-Medicaid) between individual pairs was only $84 (95% confidence interval: 44 to 124), and the mean cost difference was only $49 (95% confidence interval: -72 to 170). The 90th percentile costs were also similar between groups ($10 710 vs $10 948; P < .07). Length of stay (LOS) was also very similar; both groups had a median stay of 1 day, with a similar percentage of patients exceeding the 90th percentile of individual hospital LOS (7.1% vs 6.7%; P = .14). ICU use was also similar (10.1% vs 10.6%; P = .12).

CONCLUSIONS

For closely matched patients within the same hospital, Medicaid status did not importantly influence costs, LOS, or ICU use.

Evaluation of subset matching methods and forms of covariate balance

This paper conducts a Monte Carlo simulation study to evaluate the performance of multivariate matching methods that select a subset of treatment and control observations. The matching methods studied are the widely used nearest neighbor matching with propensity score calipers and the more recently proposed methods, optimal matching of an optimally chosen subset and optimal cardinality matching. The main findings are: (i) covariate balance, as measured by differences in means, variance ratios, Kolmogorov-Smirnov distances, and cross-match test statistics, is better with cardinality matching because by construction it satisfies balance requirements; (ii) for given levels of covariate balance, the matched samples are larger with cardinality matching than with the other methods; (iii) in terms of covariate distances, optimal subset matching performs best; (iv) treatment effect estimates from cardinality matching have lower root-mean-square errors, provided strong requirements for balance, specifically, fine balance, or strength-k balance, plus close mean balance. In standard practice, a matched sample is considered to be balanced if the absolute differences in means of the covariates across treatment groups are smaller than 0.1 standard deviations. However, the simulation results suggest that stronger forms of balance should be pursued in order to remove systematic biases due to observed covariates when a difference in means treatment effect estimator is used. In particular, if the true outcome model is additive, then marginal distributions should be balanced, and if the true outcome model is additive with interactions, then low-dimensional joints should be balanced. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of Cancer Stage and Treatment Differences on Racial Disparities in Survival From Colon Cancer: A United States Population-Based Study

BACKGROUND & AIMS

We evaluated differences in treatment of black vs white patients with colon cancer and assessed their effects on survival, based on cancer stage.

METHODS

We collected data from the Surveillance, Epidemiology, and End Results-Medicare database and identified 6190 black and 61,951 white patients with colon cancer diagnosed from 1998 through 2009 and followed up through 2011. Three sets of 6190 white patients were matched sequentially, using a minimum distance strategy, to the same set of 6190 black patients based on demographic (age; sex; diagnosis year; and Surveillance, Epidemiology, and End Results registry), tumor presentation (demographic plus comorbidities, tumor stage, grade, and size), and treatment (presentation plus therapies) variables. We conducted sensitivity analyses to explore the effects of socioeconomic status in a subcohort that included 2000 randomly selected black patients. Racial differences in treatment were assessed using a logistic regression model; their effects on racial survival disparity were evaluated using the Kaplan-Meier method and the Cox proportional hazards model.

RESULTS

After patients were matched for demographic variables, the absolute 5-year difference in survival between black and white patients was 8.3% (white, 59.2% 5-y survival; blacks, 50.9% 5-y survival) (P < .0001); this value decreased significantly, to 5.0% (P < .0001), after patients were matched for tumor presentation, and decreased to 4.9% (P < .0001) when patients were matched for treatment. Differences in treatment therefore accounted for 0.1% of the 8.3% difference in survival between black and white patients. After patients were matched for tumor presentation, racial disparities were observed in almost all types of treatment; the disparities were most prominent for patients with advanced-stage cancer (stages III or IV, up to an 11.1% difference) vs early stage cancer (stages I or II, up to a 4.3% difference). After patients were matched for treatment, there was a greater reduction in disparity for black vs white patients with advanced-stage compared with early-stage cancer. In sensitivity analyses, the 5-year racial survival disparity was 7.7% after demographic match, which was less than the 8.3% observed in the complete cohort. This reduction likely was owing to the differences between the subcohort and the complete cohort in those variables that were not included in the demographic match. This value was reduced to 6.5% (P = .0001) after socioeconomic status was included in the demographic match. The difference decreased significantly to 2.8% (P = .090) after tumor presentation match, but was not reduced further after treatment match.

CONCLUSIONS

We observed significant disparities in treatment and survival of black vs white patients with colon cancer. The disparity in survival appears to have been affected more strongly by tumor presentation at diagnosis than treatment. The effects of treatment differences on disparities in survival were greater for patients with advanced-stage vs early-stage cancer.

Large, Sparse Optimal Matching with Refined Covariate Balance in an Observational Study of the Health Outcomes Produced by New Surgeons

Every newly trained surgeon performs her first unsupervised operation. How do the health outcomes of her patients compare with the patients of experienced surgeons? Using data from 498 hospitals, we compare 1252 pairs comprised of a new surgeon and an experienced surgeon working at the same hospital. We introduce a new form of matching that matches patients of each new surgeon to patients of an otherwise similar experienced surgeon at the same hospital, perfectly balancing 176 surgical procedures and closely balancing a total of 2.9 million categories of patients; additionally, the individual patient pairs are as close as possible. A new goal for matching is introduced, called "refined covariate balance," in which a sequence of nested, ever more refined, nominal covariates is balanced as closely as possible, emphasizing the first or coarsest covariate in that sequence. A new algorithm for matching is proposed and the main new results prove that the algorithm finds the closest match in terms of the total within-pair covariate distances among all matches that achieve refined covariate balance. Unlike previous approaches to forcing balance on covariates, the new algorithm creates multiple paths to a match in a network, where paths that introduce imbalances are penalized and hence avoided to the extent possible. The algorithm exploits a sparse network to quickly optimize a match that is about two orders of magnitude larger than is typical in statistical matching problems, thereby permitting much more extensive use of fine and near-fine balance constraints. The match was constructed in a few minutes using a network optimization algorithm implemented in R. An R package called rcbalance implementing the method is available from CRAN.

Racial disparity in breast cancer survival: the impact of pre-treatment hematologic variables

PURPOSE

A survival disparity of black versus white breast cancer patients has been extensively documented but not adequately explained. Blacks and whites also have significant differences in hematologic traits including hemoglobin (HGB). However, a link between survival disparity and hematologic differences has not been reported. We aimed to explore the effect of pre-treatment hematologic variables on this survival disparity.

METHODS

We sequentially matched 443 black patients, using a minimum distance approach, to four different sets of 443 whites on demographics (age, year of diagnosis, smoking, and drinking status), tumor presentation (all demographic variables plus tumor stage, grade, and hormone receptor status), treatment (all presentation variables plus surgery, chemotherapy, radiation therapy, and hormone therapy), and presentation plus pre-treatment hematologic variables. Racial survival for each matched dataset was analyzed by Cox proportional hazards model.

RESULTS

We found that white patients matched on demographic characteristics had more favorable survival than blacks [hazard ratio (HR) 0.57, 95 % confidence interval (CI) 0.42-0.77, p log-rank = 0.0002]. Presentation match diminished this disparity [HR 0.72 (0.54-0.95), p log-rank = 0.0199], which was not further reduced in treatment match [HR 0.73 (0.55-0.96), p log-rank = 0.0249]. However, the survival disparity was largely reduced when pre-treatment level of HGB or red blood cell distribution width was further matched in addition to presentation match [HR 0.83 (0.64-1.09), p log-rank = 0.1819 and HR 0.83 (0.64-1.09), p log-rank = 0.1760, respectively].

CONCLUSIONS

We found that in our patient population, differences in tumor presentation and certain pre-treatment hematologic traits, but not treatment, were associated with the survival disparity between black and white breast cancer patients.

Erythropoiesis stimulating agents and clinical outcomes of invasive breast cancer patients receiving cytotoxic chemotherapy

The use of erythropoiesis stimulating agents (ESAs) to treat anemia in breast cancer patients who are treated with chemotherapy is a matter of ongoing debate. Several recent randomized trials challenged conventional wisdom, which holds that ESAs are contraindicated for breast cancer patients undergoing curative treatment. We aimed to perform the first large national population-based study to analyze the association between ESA use and breast cancer patient outcomes. Cytotoxic chemotherapy-treated invasive breast cancer patients were identified from the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. Non-ESA users were sequentially 1:1 matched to 2,000 randomly sampled ESA users on demographics (age, diagnosis year, race, marital status, and socioeconomic status), tumor presentation (stage, grade, and status of hormone receptors), and treatments (surgery, radiation, and sub-types of chemotherapy) using a minimum distant strategy. Breast cancer-specific survival of ESA and matched non-ESA users was compared using Fine and Gray competing risk model. Compared to ESA users, non-ESA users exhibited dramatically different baseline characteristics such as less advanced tumor, and fewer co-morbidities. Non-ESA users had a significantly more favorable breast cancer-specific survival (subdistribution hazard ratio [sHR] = 0.75, p < 0.0001). This survival disparity was progressively diminished in the sequential matching of demographics (sHR = 0.74, p = 0.0004), presentation (sHR = 0.86, p = 0.06), and treatment (sHR = 0.89, p = 0.17) variables. Stratified analyses identified subgroups of patients whose breast cancer-specific survival were not different between ESA and non-ESA users. In the SEER-Medicare database, ESA usage does not seem to be associated with unfavorable breast cancer-specific survival in breast cancer patients receiving cytotoxic chemotherapy. The ESA-breast cancer prognosis association is complex and requires more intensive investigations.

A hospital-specific template for benchmarking its cost and quality

OBJECTIVE

Develop an improved method for auditing hospital cost and quality tailored to a specific hospital's patient population.

DATA SOURCES/SETTING

Medicare claims in general, gynecologic and urologic surgery, and orthopedics from Illinois, New York, and Texas between 2004 and 2006.

STUDY DESIGN

A template of 300 representative patients from a single index hospital was constructed and used to match 300 patients at 43 hospitals that had a minimum of 500 patients over a 3-year study period.

DATA COLLECTION/EXTRACTION METHODS

From each of 43 hospitals we chose 300 patients most resembling the template using multivariate matching.

PRINCIPAL FINDINGS

We found close matches on procedures and patient characteristics, far more balanced than would be expected in a randomized trial. There were little to no differences between the index hospital's template and the 43 hospitals on most patient characteristics yet large and significant differences in mortality, failure-to-rescue, and cost.

CONCLUSION

Matching can produce fair, directly standardized audits. From the perspective of the index hospital, "hospital-specific" template matching provides the fairness of direct standardization with the specific institutional relevance of indirect standardization. Using this approach, hospitals will be better able to examine their performance, and better determine why they are achieving the results they observe.

Mortality and cardiovascular disease among older live kidney donors

Over the past two decades, live kidney donation by older individuals (≥55 years) has become more common. Given the strong associations of older age with cardiovascular disease (CVD), nephrectomy could make older donors vulnerable to death and cardiovascular events. We performed a cohort study among older live kidney donors who were matched to healthy older individuals in the Health and Retirement Study. The primary outcome was mortality ascertained through national death registries. Secondary outcomes ascertained among pairs with Medicare coverage included death or CVD ascertained through Medicare claims data. During the period from 1996 to 2006, there were 5717 older donors in the United States. We matched 3368 donors 1:1 to older healthy nondonors. Among donors and matched pairs, the mean age was 59 years; 41% were male and 7% were black race. In median follow-up of 7.8 years, mortality was not different between donors and matched pairs (p = 0.21). Among donors with Medicare, the combined outcome of death/CVD (p = 0.70) was also not different between donors and nondonors. In summary, carefully selected older kidney donors do not face a higher risk of death or CVD. These findings should be provided to older individuals considering live kidney donation.

Template matching for auditing hospital cost and quality

OBJECTIVE

Develop an improved method for auditing hospital cost and quality.

DATA SOURCES/SETTING

Medicare claims in general, gynecologic and urologic surgery, and orthopedics from Illinois, Texas, and New York between 2004 and 2006.

STUDY DESIGN

A template of 300 representative patients was constructed and then used to match 300 patients at hospitals that had a minimum of 500 patients over a 3-year study period.

DATA COLLECTION/EXTRACTION METHODS

From each of 217 hospitals we chose 300 patients most resembling the template using multivariate matching.

PRINCIPAL FINDINGS

The matching algorithm found close matches on procedures and patient characteristics, far more balanced than measured covariates would be in a randomized clinical trial. These matched samples displayed little to no differences across hospitals in common patient characteristics yet found large and statistically significant hospital variation in mortality, complications, failure-to-rescue, readmissions, length of stay, ICU days, cost, and surgical procedure length. Similar patients at different hospitals had substantially different outcomes.

CONCLUSION

The template-matched sample can produce fair, directly standardized audits that evaluate hospitals on patients with similar characteristics, thereby making benchmarking more believable. Through examining matched samples of individual patients, administrators can better detect poor performance at their hospitals and better understand why these problems are occurring.

Racial disparities in operative procedure time: the influence of obesity

BACKGROUND

Using Pennsylvania Medicare claims from 1995 to 1996, the authors previously reported that anesthesia procedure length appears longer in blacks than whites. In a new study using a different and larger data set, the authors now examine whether body mass index (BMI), not available in Medicare claims, explains this difference. The authors also examine the relative contributions of surgical and anesthesia times.

METHODS

The Obesity and Surgical Outcomes Study of 47 hospitals throughout Illinois, New York, and Texas abstracted chart information including BMI on elder Medicare patients (779 blacks and 14,596 whites) undergoing hip and knee replacement and repair, colectomy, and thoracotomy between 2002 and 2006. The authors matched all black Medicare patients to comparable whites and compared procedure lengths.

RESULTS

Mean BMI in the black and white populations was 30.24 and 28.96 kg/m, respectively (P<0.0001). After matching on age, sex, procedure, comorbidities, hospital, and BMI, mean white BMI in the comparison group was 30.1 kg/m (P=0.94). The typical matched pair difference (black-white) in anesthesia (induction to recovery room) procedure time was 7.0 min (P=0.0019), of which 6 min reflected the surgical (cut-to-close) time difference (P=0.0032). Within matched pairs, where the difference in procedure times was greater than 30 min between patients, blacks more commonly had longer procedure times (Odds=1.39; P=0.0008).

CONCLUSIONS

Controlling for patient characteristics, BMI, and hospital, elder black Medicare patients experienced slightly but significantly longer procedure length than their closely matched white controls. Procedure length difference was almost completely due to surgery, not anesthesia.