Implications of Payment for Acute Myocardial Infarctions as a 90-Day Bundled Single Episode of Care: A Cost of Illness Analysis.

OBJECTIVES: Evaluate the cost of illness associated with the 90-day period following acute myocardial infarction (AMI) and the implication of care pathway (percutaneous coronary intervention [PCI] vs medical management [MM]), in order to assess the potential financial risk incurred by providers for AMI as an episode of care. PERSPECTIVE: Reimbursement payment systems for acute care episodes are shifting from 30-day to 90-day bundled payment models. Since follow-up care and readmissions beyond the early days/weeks post-AMI are common, financial risk may be transferred to providers. SETTING: AMI hospitalization Centers for Medicare & Medicaid Services (CMS) standard analytical files between 10/1/2015 and 9/30/2016 were reviewed. METHODS: Included patients were Medicare beneficiaries with a primary diagnosis of AMI subsequently treated with either PCI or MM. Payments were standardized to remove geographic variation and separated into reimbursements for services during the hospitalization and from discharge to 90 days post-discharge. Results were stratified by Medicare Severity Diagnosis Related Groups (MS-DRGs) individually and grouped between patients treated with MM and PCI. Risk-adjusted likelihood of utilization of post-acute nursing care and all-cause readmission was assessed by logistic regression. RESULTS: A total of 96,546 patients were included in the analysis. The highest total mean payment (US$32,714) was for MS-DRG 248 (PCI with non-drug-eluting stent with major complication or comorbidity). Total payments were similar between MM and PCI patients, but MM patients incurred the majority of costs in the post-acute period after discharge, with the converse true for PCI patients. MM without catheterization was associated with a twofold increase in risk of requiring post-acute nursing care and 90-day readmission versus PCI (odds ratio [95% confidence interval]: 2.01 [1.92-2.11] and 2.17 [2.08-2.27]). Smaller hospital size, diabetes, peripheral arterial disease, prior AMI, and multivessel disease were predictors of higher healthcare utilization. CONCLUSIONS: MS-DRGs associated with the lowest reimbursements (and presumably, lowest costs of inpatient care) incur the highest post-discharge expenditures. As the CMS Bundled Payment for Care Improvement and similar programs are implemented, there will be a need to account for heterogeneous post-discharge care costs. Video abstract (MP4 274659 KB).

Around 805,000 heart attacks occur annually in the US. With an average age over 65 years, many heart attack patients qualify for Medicare health insurance. Under Medicare, hospitals (or 'providers') receive reimbursements for the cost of care associated with 'acute care episodes' (e.g., heart attacks) as a 'bundled' payment. The bundled reimbursements are typically based on pre-defined prices, with hospitals paying the difference if actual costs exceed these. Reimbursements are typically given for care costs from the initial heart attack through to hospital discharge and care in the 30-day post-discharge period. However, recently introduced reimbursement models such as BPCI Advanced have moved to expand this to 90 days. Since follow-up care and additional cardiovascular readmissions are common beyond 30 days, extension of the reimbursement period to 90 days could increase financial risk to hospitals/providers if these additional costs are not included in reimbursements. To assess the potential impact of this, we investigated the cost of illness for heart attack and the implication of type of care: medical management (standard medication given after heart attack) vs. percutaneous coronary intervention (PCI; standard medication plus a non-surgical procedure to widen heart blood vessels). We found that 90-day costs after heart attack are substantial regardless of type of care. We found that post-discharge costs were generally high, but higher for medically managed patients than those receiving PCI. Our analysis also suggests Medicare disease classifications associated with lowest payments for heart attack (and presumably, lowest hospitalization costs) are associated with the highest post-discharge expenditures. Overall, our study suggests that new payment models should account for variable post-discharge care costs, and new therapies are needed to reduce additional events, readmissions, and associated costs in heart attack patients.

Assessment of oxygen consumption in response to progressive hypoxia.

A new method is presented for describing the rate of oxygen consumption in response to progressive hypoxia. The method consists of screening candidate functions describing the relationship between Vo2 (oxygen consumption rate) and Po2 (ambient oxygen concentration) by testing each for fit to observed data for a single curve and the function that best fits is chosen using lowest AICc value as the criterion. Descriptive statistics are then extracted from the selected function that best describes the pattern present in the curve. Several new descriptive statistics for the pattern of response are proposed which are based on the null model of simple diffusion and no regulation. The method quantifies deviation from the null model at each point on the curve and measures both positive and negative deviation which occur when the curve changes more slowly or more rapidly than the null model predicts, respectively. The new descriptive statistics generalize the traditional one used in the past, the critical oxygen tension (Pc), and allow interpretation of a variety of shapes of curves which cannot be analyzed with conventional methods. Because the method is descriptive, it does not implicate any specific mechanisms in generating the response. The method is applied to data from 68 animals in 14 different species groups reported in the literature. The overall results suggest the existence of substantial diversity in response types among animals, which requires a more complex description than has traditionally been used.

Respiratory response to temperature and hypoxia in the zebra mussel Dreissena polymorpha.

The effects of temperature acclimation, acute temperature variation and progressive hypoxia on oxygen consumption rates (VO2) were determined for the zebra mussel Dreissena polymorpha. In the first experiment, after acclimation to 5, 15 or 25 degrees C for at least 2 weeks, VO2 was determined at 5 degrees C increments from 5 to 45 degrees C. VO2 increased in all three acclimation groups from 5 to 30 degrees C, corresponding to the normal ambient temperature range for this species. Mussels displayed imperfect temperature compensation at temperatures above 15 degrees C, but exhibited little acclimatory ability below 15 degrees C. In the hypoxia experiment, VO2 was determined over the course of progressive hypoxia, from full saturation (oxygen tension [PO2]=160 Torr [21.3 kPa]) to a PO2 at which oxygen uptake ceased (<10 Torr [1.3 kPa]). Mussels were acclimated to either 5, 15 or 25 degrees C for at least 2 weeks and their respiratory response to progressive hypoxia was measured at three test temperatures (5, 15 and 25 degrees C). The degree of oxygen regulation increased with increasing test temperature, particularly from 5 to 15 degrees C, but decreased with increasing acclimation temperature. The decreased metabolic rate observed for warm-acclimated animals, particularly in the upper portion of the temperature range of the zebra mussel, may allow for conservation of organic energy stores during warm summer months. Compared to other freshwater bivalves, D. polymorpha is a relatively poor oxygen regulator, corresponding with its preference for well-oxygenated aquatic habitats. In addition, a new quantitative method for determining the degree of oxygen regulation is presented.