Publications

Background Mortality prediction in critically ill patients with cardiogenic shock can guide triage and selection of potentially high-risk treatment options. Methods and Results We developed and externally validated a checklist risk score to predict in-hospital mortality among adults admitted to the cardiac intensive care unit with Society for Cardiovascular Angiography & Interventions Shock Stage C or greater cardiogenic shock using 2 real-world data sets and Risk-Calibrated Super-sparse Linear Integer Modeling (RiskSLIM). We compared this model to those developed using conventional penalized logistic regression and published cardiogenic shock and intensive care unit mortality prediction models. There were 8815 patients in our training cohort (in-hospital mortality 13.4%) and 2237 patients in our validation cohort (in-hospital mortality 22.8%), and there were 39 candidate predictor variables. The final risk score (termed BOS,MA2) included maximum blood urea nitrogen ≥25 mg/dL, minimum oxygen saturation <88%, minimum systolic blood pressure <80 mm Hg, use of mechanical ventilation, age ≥60 years, and maximum anion gap ≥14 mmol/L, based on values recorded during the first 24 hours of intensive care unit stay. Predicted in-hospital mortality ranged from 0.5% for a score of 0 to 70.2% for a score of 6. The area under the receiver operating curve was 0.83 (0.82-0.84) in training and 0.76 (0.73-0.78) in validation, and the expected calibration error was 0.9% in training and 2.6% in validation. Conclusions Developed using a novel machine learning method and the largest cardiogenic shock cohorts among published models, BOS,MA2 is a simple, clinically interpretable risk score that has improved performance compared with existing cardiogenic-shock risk scores and better calibration than general intensive care unit risk scores.

IMPORTANCE: Recent studies have produced inconsistent findings regarding the outcomes of the percutaneous microaxial left ventricular assist device (LVAD) during acute myocardial infarction with cardiogenic shock (AMICS).

OBJECTIVE: To compare the percutaneous microaxial LVAD vs alternative treatments among patients presenting with AMICS using observational analyses of administrative data.

DESIGN, SETTING, AND PARTICIPANTS: This comparative effectiveness research study used Medicare fee-for-service claims of patients admitted with AMICS undergoing percutaneous coronary intervention from October 1, 2015, through December 31, 2019. Treatment strategies were compared using (1) inverse probability of treatment weighting to estimate the effect of different baseline treatments in the overall population; (2) instrumental variable analysis to determine the effectiveness of the percutaneous microaxial LVAD among patients whose treatment was influenced by cross-sectional institutional practice patterns; (3) an instrumented difference-in-differences analysis to determine the effectiveness of treatment among patients whose treatment was influenced by longitudinal changes in institutional practice patterns; and (4) a grace period approach to determine the effectiveness of initiating the percutaneous microaxial LVAD within 2 days of percutaneous coronary intervention. Analysis took place between March 2021 and December 2022.

INTERVENTIONS: Percutaneous microaxial LVAD vs alternative treatments (including medical therapy and intra-aortic balloon pump).

MAIN OUTCOMES AND MEASURES: Thirty-day all-cause mortality and readmissions.

RESULTS: Of 23 478 patients, 14 264 (60.8%) were male and the mean (SD) age was 73.9 (9.8) years. In the inverse probability of treatment weighting analysis and grace period approaches, treatment with percutaneous microaxial LVAD was associated with a higher risk-adjusted 30-day mortality (risk difference, 14.9%; 95% CI, 12.9%-17.0%). However, patients receiving the percutaneous microaxial LVAD had a higher frequency of factors associated with severe illness, suggesting possible confounding by measures of illness severity not available in the data. In the instrumental variable analysis, 30-day mortality was also higher with percutaneous microaxial LVAD, but patient and hospital characteristics differed across levels of the instrumental variable, suggesting possible confounding by unmeasured variables (risk difference, 13.5%; 95% CI, 3.9%-23.2%). In the instrumented difference-in-differences analysis, the association between the percutaneous microaxial LVAD and mortality was imprecise, and differences in trends in characteristics between hospitals with different percutaneous microaxial LVAD use suggested potential assumption violations.

CONCLUSIONS: In observational analyses comparing the percutaneous microaxial LVAD to alternative treatments among patients with AMICS, the percutaneous microaxial LVAD was associated with worse outcomes in some analyses, while in other analyses, the association was too imprecise to draw meaningful conclusions. However, the distribution of patient and institutional characteristics between treatment groups or groups defined by institutional differences in treatment use, including changes in use over time, combined with clinical knowledge of illness severity factors not captured in the data, suggested violations of key assumptions that are needed for valid causal inference with different observational analyses. Randomized clinical trials of mechanical support devices will allow valid comparisons across candidate treatment strategies and help resolve ongoing controversies.

BACKGROUND: Frailty is increasingly recognized as a useful measure of vulnerability in older adults. Multiple claims-based frailty indices (CFIs) can readily identify individuals with frailty, but whether 1 CFI improves prediction over another is unknown. We sought to assess the ability of 5 distinct CFIs to predict long-term institutionalization (LTI) and mortality in older Veterans.

METHODS: Retrospective study conducted in U.S. Veterans ≥65 years without prior LTI or hospice use in 2014. Five CFIs were compared: Kim, Orkaby (Veteran Affairs Frailty Index [VAFI]), Segal, Figueroa, and the JEN-FI, grounded in different theories of frailty: Rockwood cumulative deficit (Kim and VAFI), Fried physical phenotype (Segal), or expert opinion (Figueroa and JFI). The prevalence of frailty according to each CFI was compared. CFI performance for the coprimary outcomes of any LTI or mortality from 2015 to 2017 was examined. Because Segal and Kim include age, sex, or prior utilization, these variables were added to regression models to compare all 5 CFIs. Logistic regression was used to calculate model discrimination and calibration for both outcomes.

RESULTS: A total of 3 million Veterans were included (mean age 75, 98% male participants, 80% White, and 9% Black). Frailty was identified for between 6.8% and 25.7% of the cohort with 2.6% identified as frail by all 5 CFIs. There was no meaningful difference between CFIs in the area under the receiver operating characteristic curve for LTI (0.78-0.80) or mortality (0.77-0.79).

CONCLUSIONS: Based on different frailty constructs, and identifying different subsets of the population, all 5 CFIs similarly predicted LTI or death, suggesting each could be used for prediction or analytics.

PURPOSE: The value of intravascular ultrasound (IVUS) guidance during peripheral vascular revascularization procedures is incompletely understood. Moreover, data on long-term clinical outcomes and costs are limited. The objective of this study was to compare outcomes and costs between IVUS and contrast angiography alone in patients undergoing peripheral revascularization procedures in Japan.

MATERIALS AND METHODS: This retrospective comparative analysis was performed using the Japanese Medical Data Vision insurance claims database. All patients undergoing revascularization for peripheral artery disease (PAD) between April 2009 and July 2019 were included. Patients were followed until July 2020, death, or a subsequent revascularization procedure for PAD. Two patient groups were compared: one undergoing IVUS imaging or the other contrast angiography alone. The primary end point was major adverse cardiac and limb events, including all-cause-mortality, endovascular thrombolysis, subsequent revascularization procedures for PAD, stroke, acute myocardial infarction, and major amputations. Total health care costs were documented over the follow-up and compared between groups, using a bootstrap method.

RESULTS: The study included 3956 patients in the IVUS group and 5889 in the angiography alone group. Intravascular ultrasound was significantly associated with reduced risk of a subsequent revascularization procedure (adjusted hazard ratio: 0.25 [0.22-0.28]) and major adverse cardiac and limb events (0.69 [0.65-0.73]). The total costs were significantly lower in the IVUS group, with a mean cost saving over follow-up of $18 173 [$7 695-$28 595] per patient.

CONCLUSION: The use of IVUS during peripheral revascularization provides superior long-term clinical outcomes at lower costs compared with contrast angiography alone, warranting wider adoption and fewer barriers to IVUS reimbursement for patients with PAD undergoing routine revascularization.

CLINICAL IMPACT: Intravascular ultrasound (IVUS) guidance during peripheral vascular revascularization has been introduced to improve the precision of the procedure. However, questions over the benefit of IVUS in terms of long-term clinical outcome and over cost have limited its use in everyday clinical practice. This study, performed in a Japanese health insurance claims database, demonstrates that use of IVUS provides a superior clinical outcome over the long term at a lower cost compared to angiography alone. These findings should encourage clinicians to use IVUS in routine peripheral vascular revascularization procedures and encourage providers to reduce barriers to use.

Estimating the likelihood of urgent mechanical circulatory support (MCS) can facilitate procedural planning and clinical decision-making in chronic total occlusion (CTO) percutaneous coronary intervention (PCI). We analyzed 2,784 CTO PCIs performed between 2012 and 2021 at 12 centers. The variable importance was estimated by a bootstrap applying a random forest algorithm to a propensity-matched sample (a ratio of 1:5 matching cases with controls on center). The identified variables were used to predict the risk of urgent MCS. The performance of the risk model was assessed in-sample and on 2,411 out-of-sample procedures that did not require urgent MCS. Urgent MCS was used in 62 (2.2%) of cases. Patients who required urgent MCS were older (70 [63 to 77] vs 66 [58 to 73] years, p = 0.003) compared with those who did not require urgent MCS. Technical (68% vs 87%, p <0.001) and procedural success (40% vs 85%, p <0.001) was lower in the urgent MCS group compared with cases that did not require urgent MCS. The risk model for urgent MCS use included retrograde crossing strategy, left ventricular ejection fraction, and lesion length. The resulting model demonstrated good calibration and discriminatory capacity with the area under the curve (95% confidence interval) of 0.79 (0.73 to 0.86) and specificity and sensitivity of 86% and 52%, respectively. In the out-of-sample set, the specificity of the model was 87%. The Prospective Global Registry for the Study of Chronic Total Occlusion Intervention CTO MCS score can help estimate the risk of urgent MCS use during CTO PCI.

Clinician payment is transitioning from fee-for-service to value-based payment, with reimbursement tied to health care quality and cost. However, the overarching goals of value-based payment-to improve health care quality, lower costs, or both-have been largely unmet. This policy statement reviews the current state of value-based payment and provides recommended best practices for future design and implementation. The policy statement is divided into sections that detail different aspects of value-based payment: (1) key program design features (patient population, quality measurement, cost measurement, and risk adjustment), (2) the role of equity during design and evaluation, (3) adjustment of payment, and (4) program implementation and evaluation. Each section introduces the topic, describes important considerations, and lists examples from existing programs. Each section includes recommended best practices for future program design. The policy statement highlights 4 key themes for successful value-based payment. First, programs should carefully weigh the incentives between lowering cost and improving quality of care and ensure that there is adequate focus on quality of care. Second, the expansion of value-based payment should be a tool for improving equity, which is central to quality of care and should be a focal point of program design and evaluation. Third, value-based payment should continue to move away from fee for service toward more flexible funding that allows clinicians to focus resources on the interventions that best help patients. Last, successful programs should find ways to channel clinicians' intrinsic motivation to improve their performance and the care for their patients. These principles should guide the future development of clinician value-based payment models.

OBJECTIVE: To examine the effects of Medicare eligibility and enrollment on the use of high-value and low-value care services.

DATA SOURCES/STUDY SETTING: The 2002-2019 Medical Expenditure Panel Survey.

STUDY DESIGN: We employed a regression discontinuity design, which exploits the discontinuity in eligibility for Medicare at age 65 and compares individuals just before and after age 65. Our primary outcomes included the use of high-value care services (eight services) and low-value care services (seven services). To examine the effects of Medicare eligibility, we conducted a regression discontinuity analysis. To examine the effects of Medicare enrollment, we used the discontinuity in the probability of having Medicare coverage around the age eligibility cutoff and conducted an instrumental variable analysis.

DATA COLLECTION/EXTRACTION METHODS: N/A.

PRINCIPAL FINDINGS: Medicare eligibility and enrollment led to statistically significant increases in the use of only two high-value services: cholesterol measurement [2.1 percentage points (95%: 0.4-3.7) (2.2% relative change) and 2.4 percentage points (95%: 0.4-4.4)] and receipt of the influenza vaccine [3.0 percentage points (95%: 0.3-5.6) (6.0% relative change) and 3.6 percentage points (95%: 0.4-6.8)]. Medicare eligibility and enrollment led to statistically significant increases in the use of two low-value services: antibiotics for acute upper respiratory infections [6.9 percentage points (95% CI: 0.8-13.0) (24.0% relative change) and 8.2 percentage points (95% CI: 0.8-15.5)] and radiographs for back pain [4.6 percentage points (95% CI: 0.1-9.2) (36.8% relative change) and 6.2 percentage points (95% CI: 0.1-12.3)]. However, there was no significant change in the use of other high-value and low-value care services.

CONCLUSION: Medicare eligibility and enrollment at age 65 years led to increases in the use of some high-value and low-value care services, but there were no changes in the use of the majority of other services. Policymakers should consider refining the Medicare program to enhance the value of care delivered.