Drivers of costs associated with reperfusion therapy in acute stroke: the Interventional Management of Stroke III Trial

Abstract

Background and purpose: The Interventional Management of Stroke (IMS) III study tested the effect of intravenous tissue-type plasminogen activator (tPA) alone when compared with intravenous tPA followed by endovascular therapy and collected cost data to assess the economic implications of the 2 therapies. This report describes the factors affecting the costs of the initial hospitalization for acute stroke subjects from the United States.

Methods: Prospective cost analysis of the US subjects was treated with intravenous tPA alone or with intravenous tPA followed by endovascular therapy in the IMS III trial. Results were compared with expected Medicare payments.

Results: The adjusted cost of a stroke admission in the study was $35 130 for subjects treated with endovascular therapy after intravenous tPA treatment and $25 630 for subjects treated with intravenous tPA alone (P<0.0001). Significant factors related to costs included treatment group, baseline National Institutes of Health Stroke Scale, time from stroke onset to intravenous tPA, age, stroke location, and comorbid diabetes mellitus. The mean cost for subjects who had routine use of general anesthesia as part of endovascular therapy was $46 444 when compared with $30 350 for those who did not have general anesthesia. The costs of embolectomy for IMS III subjects and patients from the National Inpatient Sample cohort exceeded the Medicare diagnosis-related group payment in ≥75% of patients.

Conclusions: Minimizing the time to start of intravenous tPA and decreasing the use of routine general anesthesia may improve the cost-effectiveness of medical and endovascular therapy for acute stroke.

Clinical trial registration url: http://www.clinicaltrials.gov. Unique identifier: NCT00359424.

Keywords: brain ischemic; costs and cost analysis; hospitals; reperfusion; stroke.

Figure 1. Adjusted* Present Value Costs by Treatment Group, Time of IV t-PA Administration and Stroke Severity

*adjusted for intubation

Figure 2. Mean Charges by Category

Note: Anesthesia is grouped with Operating costs, and blood products are grouped with Other costs.

Figure 3. Subject Treated with t-PA Alone and Those Treated with t-PA followed by Endovascular Therapy Using Embolectomy Devices in IMS III and NIS Cohorts

Cumulative cost curves for AIS patients receiving IV t-PA alone (red curves) included data from IMS III subjects randomized to t-PA Alone (IMS IV Alone) and HCUP National Inpatient Sample (NIS) patients who received IV t-PA but did not have an endovascular procedure code or a DRG classification indicating an endovascular intervention (NIS t-PA). Cumulative cost curves for IMS III subjects who were randomized to endovascular treatment with embolectomy devices (black solid line) and NIS patients who had both a t-PA procedure code (indicating received t-PA) and an endovascular procedure code or DRG classification indicating embolectomy (black interrupted line) are provided. Medicare 2012 payment levels (without any hospital-specific payment for teaching or regional factors) for the DRGs most relevant to IMS III are indicated by the vertical lines. DRG 61 is national payment for AIS with use of thrombolytic agent with major comorbid condition (MCC), DRG 62 is payment with comorbid condition (CC), and DRG 63 is payment without MCC or CC. To best reflect IMS III in this figure DRG 23 is payment for AIS with embolectomy (Craniotomy with major device implant or acute complex CNS PDX w MCC) and a t-PA procedure code, and DRG 24 is payment for AIS with embolectomy as defied above without MCC and a t-PA procedure code. Payment and cost of providing care is equal (on average) if the payment line crosses the cumulative cost cure at the 50% mark. Payments are inadequate for covering cost of care (on average) if the payment line crosses the cumulative cost curve at a point lower than 50%, and payment exceeds cost of care (on average) if the payment line crosses the cumulative cost curve above the 50% mark. The observed cost curves for IMS III subjects treated with IV t-PA alone appear slightly higher than the cost curve for the NIS stroke patients with an ICD-9 code of t-PA, reflecting the exclusion of mild strokes from the trial. Further, the expected Medicare payments for MS-DRGs 61, 62 and 63 fall below the 50^th percentile on the cumulative cost curves, indicating that payment for these stroke patients may be slightly less than the cost of care provided. A different pattern is observed for subjects who had embolectomy following t-PA. Here the cumulative cost curve for IMS III subjects fall to the left of the curve for NIS patients. This indicates that the IMS subjects have lower median cost than the costs estimated for the NIS patients. Furthermore, the expected payment for both groups fall far left of the median of the cost curves. This means that the typical Medicare DRG payment will be lower than what it costs a hospital to treat such a patient in a majority of cases. For the IMS III subjects, we may expect the care of 75 percent of subjects to cost more than the Medicare DRG payment will reimburse, while the expected DRG payment will not cover the cost of care for 85 percent of patients in the NIS cohort.