The MHS provided a unique opportunity to examine population trends in AMI mortality and hospital care. We observed a steady decline in hospital LOS from 1985 to 2001. During this 17-year interval, there was also a decrease in 1 month post-discharge mortality.
The safety and feasibility of early discharge following an AMI has been a focus of debate spurred by increasing economic pressures within the healthcare system. Hospital LOS has steadily declined over the past half century. In the 1960s it was routine to hospitalize patients with AMI for several weeks. Decreasing LOS has paralleled a transition from passive care (bed rest, telemetry, and antiplatelet therapy) to active contemporary care (pharmacologic and mechanical reperfusion therapy, the development and utilization of combined pharmacologic agents, and rehabilitation). Ironically, decreasing hospital LOS has been associated with increasing hospital cost. The total average charge for treating a heart attack patient rose from $20,578 in 1993 to $28,663 in 2000, while the average hospital LOS fell by 26%—from 7.4 days to 5.5 days.10
These findings raised concerns that reduced hospital LOS may be compromising patient care leading to poor outcomes.
The complex interaction of factors involved in determining hospital LOS has been illustrated by several studies.11,12
Severity of patient illness, physician practice styles, patient preferences, and financial constraints imposed by hospitals and insurance carriers all play roles. In an analysis of patients undergoing CABG in the Cooperative Cardiovascular Project, Rosen observed significant variability in LOS between institutions after adjusting for both preoperative clinical characteristics and postoperative complications.12
McCormick observed similar variability among 1188 patients admitted to community hospitals with pneumonia.11
Interestingly, patients with a shorter LOS did not have any worse outcome than those with a longer hospital stay. These data support the notion that hospital LOS is driven to some extent by non-clinical factors and that there was room for improved efficiency.
Investigators have attempted to identify patients at low risk of subsequent morbidity and mortality. In the GUSTO trial, Newby defined an “uncomplicated” myocardial infarction as the absence of death, re-infarction, ischemia, stroke, shock, heart failure, bypass surgery, balloon pumping, emergency catheterization or cardioversion/defibrillation during the first 4 hospital days.7
The 30-day mortality in this group was 1% and the rates of re-infarction (1.7%), recurrent ischemia (6.7%), and stroke (0.2%) were quite low.
Several studies have prospectively evaluated hospital LOS following AMI.2–5
Grines, in the PAMI-II trial (1993–1995), randomized 462 low-risk AMI patients (age ≤ 70, left ventricular ejection fraction > 45%, 1 or 2 vessel disease, successful coronary intervention, and no persistent arrhythmias) treated with primary coronary intervention to either discharge on day 3 or to traditional care.2
At 6 months, the accelerated and traditional care groups had similar rates of mortality, unstable ischemia, re-infarction, and stroke. Van der Vlugt, in the SHORT trial (1993–1995), developed a decision rule for identifying low risk AMI patients (absence of ventricular fibrillation, heart failure, recurrent infarction, and advanced AV block during the first 3 days and absence of angina and symptomatic arrhythmias between days 3 and 7) who could be discharged on day 7.3
Among the 43% of the patients who qualified for early discharge, none died within 1 month of discharge and the readmission rate for recurrent myocardial infarction and heart failure was 1.8%. Senaratne evaluated the feasibility of discharging patients directly from the coronary care unit.4
The mean length of hospitalization of 5 days with an in-hospital mortality of 5.8%, and a 6-week post discharge mortality of 2.7%; only 2 deaths occurred within 48 hours of discharge. Most recently, Bogaty et al. randomized 120 low-risk AMI patients to a discharge on day 3 versus a standard stay. Short-stay patients had 25% fewer cardiovascular procedures with similar adverse event and rehospitalization rates at 6 months.5
Our findings in a population-based sample are consistent with the results of these clinical trials, although the mean LOS was slightly longer in this community than in the clinical trials. Our data reflect the natural course of an unselected population of patients with AMI and a diversity of care protocols in community hospitals. In contrast to selected patients enrolled in clinical trials and prospective studies, the patients in the MHS would be expected to have increased morbidity and mortality. Our observations are further supported by recently published data from the Worcester Heart Attack Study.6
Spencer et al. analyzed 4551 AMI discharges from 1986 to 1999 and found no increase in post-discharge mortality among patients with a hospital LOS less than 6 days. In contrast, 30-day and 90-day mortality was increased among patients hospitalized longer than 2 weeks.
The trend toward reduced 30-day post discharge mortality between 1985 and 2001 contrasts with our expectations given the observed reduction in LOS, leading us to reject our initial hypothesis. One explanation may stem from the increased utilization of more sensitive cardiac serum biomarkers in recent years. Patients with limited myocardial injury can now be readily identified and this group of patients may have a better prognosis than those patients with larger myocardial infarctions. A second explanation may rest within better risk stratification and treatment of patients with myocardial infarction. Technologic advances now permit early diagnosis of AMI and allow for more rapid triage of patients. Advances in medical therapy combined with the early use of coronary angiography and revascularization now ensure improved survival to a group of patients traditionally viewed as high risk. This more “streamlined” process is clearly more efficient and presumably leads to earlier discharge while avoiding increased patient risk. There also remains the possibility that the reduced LOS has been primarily driven by hospital policy and insurance carriers.
There were several limitations to our study. First, the overall post-discharge mortality was quite low for all 4 sample frames and was inadequate to permit additional modeling of hospital LOS. However, this low mortality is echoed by other AMI studies, both prospective clinical trials and retrospective observational analyses. Second, the reported mortality rates may be an underestimate of the true mortality since out-of-state mortality was not identified. For this reason, the analysis was restricted to in-state residents. We would not expect a significant relocation of Minnesota residents within a month or even 6 months of a heart attack. Third, HIPAA regulations necessitated the use of a third-party to perform the mortality follow up and prohibited us from analyzing other outcomes such as readmissions for reinfarction and heart failure. Finally, it is possible that the data derived from the MHS project may not reflect national practice and mortality trends. The fact that the MHS incorporates data from all hospitals in the Minneapolis-St. Paul metropolitan area and the similar trend between the MHS and national mortality rates following AMI would argue to the contrary.