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Declining Length of Stay for Patients Hospitalized with AMI: Impact on Mortality and Readmissions

      Abstract

      Background

      Length of hospital stay after acute myocardial infarction decreased significantly in the 1980s and 1990s. Whether length of stay has continued to decrease during the 2000s, and the impact of decreasing length of stay on rehospitalization and mortality, is unclear. We describe decade-long (1995-2005) trends in length of stay after acute myocardial infarction, and examine whether declining length of stay has impacted early rehospitalization and postdischarge mortality in a population-based sample of hospitalized patients.

      Methods

      The study sample consisted of 4184 patients hospitalized with acute myocardial infarction in a central New England metropolitan area during 6 annual periods (1995, 1997, 1999, 2001, 2003, 2005).

      Results

      The average age of the study sample was 71 years, and 54% were men. The average length of stay decreased by nearly one third over the 10-year study period, from 7.2 days in 1995 to 5.0 days in 2005 (P <.001). Younger patients (<65 years), men, and patients with an uncomplicated hospital stay had significantly shorter lengths of stay than respective comparison groups. Lengths of stay shorter than the median were not associated with significantly higher odds of hospital readmission at 7 or 30 days postdischarge, or with mortality in the year after discharge. In contrast, longer lengths of stay were associated with significantly higher odds of short-term mortality. These findings did not vary by year under study.

      Conclusions

      Length of stay in patients hospitalized for acute myocardial infarction decreased significantly between 1995 and 2005. Declining length of stay is not associated with an increased risk for early readmission or all-cause mortality.

      Keywords

      Length of hospital stay in patients with acute myocardial infarction has decreased significantly over the past two decades from an average duration of more than 10 days in the 1980s to between 6 and 8 days in the 1990s.
      • Baker D.W.
      • Einstadter D.
      • Husak S.S.
      • Cebul R.D.
      Trends in postdischarge mortality and readmissions: has length of stay declined too far?.
      • Berger A.K.
      • Duval S.
      • Jacobs Jr, D.R.
      • et al.
      Relation of length of hospital stay in acute myocardial infarction to postdischarge mortality.
      • Spencer F.A.
      • Lessard D.
      • Gore J.M.
      • Yarzebski J.
      • Goldberg R.J.
      Declining length of hospital stay for acute myocardial infarction and postdischarge outcomes: a community-wide perspective.
      Declining length of stay potentially results in a greater number of patients at risk for early hospital readmission and for dying in the weeks following hospital discharge.
      • Over the 10-year period under study (1995-2005), there was a nearly one-third decrease in the average and median length of stay in patients hospitalized with acute myocardial infarction.
      • Shorter lengths of stay did not adversely affect the risk of hospital readmission 7 and 30 days after hospital discharge or mortality in the 30 and 90 days following discharge.
      • Younger patients (<65 years), men, and patients with an uncomplicated hospital stay had significantly shorter lengths of stay than respective comparison groups.
      While post discharge mortality rates after hospitalization for acute myocardial infarction have decreased over the past 2 decades, it remains unclear whether shorter lengths of stay are associated with higher death and rehospitalization rates after hospital discharge for acute myocardial infarction.
      • Botkin N.F.
      • Spencer F.A.
      • Goldberg R.J.
      • Lessard D.
      • Yarzebski J.
      • Gore J.M.
      Changing trends in the long-term prognosis of patients with acute myocardial infarction: a population-based perspective.
      • Parikh N.I.
      • Gona P.
      • Larson M.G.
      • et al.
      Long-term trends in myocardial infarction incidence and case fatality in the National Heart, Lung, and Blood Institute's Framingham Heart Study.
      • Masoudi F.A.
      • Foody J.M.
      • Havranek E.P.
      • et al.
      Trends in acute myocardial infarction in 4 US states between 1992 and 2001: clinical characteristics, quality of care, and outcomes.
      In a study of more than 8600 Medicare patients hospitalized with acute myocardial infarction between 1991 and 1997, significant decreases in length of stay were associated with increases in hospital readmissions within 30 days of the index event.
      • Baker D.W.
      • Einstadter D.
      • Husak S.S.
      • Cebul R.D.
      Trends in postdischarge mortality and readmissions: has length of stay declined too far?.
      In addition, while declining length of stay was not associated with higher 30-day death rates in all patients, increased postdischarge mortality was observed in patients hospitalized for acute myocardial infarction who had early do-not-resuscitate (DNR) orders, suggesting that certain groups may be at risk for poorer outcomes following shorter hospital stays.
      While the economic benefit and safety of “early” hospital discharge in patients with an uncomplicated acute myocardial infarction has been noted in previous clinical trials carried out during the 1990s,
      • Desideri A.
      • Fioretti P.M.
      • Cortigiani L.
      • et al.
      Cost of strategies after myocardial infarction (COSTAMI): a multicentre, international, randomized trial for cost-effective discharge after uncomplicated myocardial infarction.
      • Topol E.J.
      • Burek K.
      • O'Neill W.W.
      • et al.
      A randomized controlled trial of hospital discharge three days after myocardial infarction in the era of reperfusion.
      • Newby L.K.
      • Eisenstein E.L.
      • Califf R.M.
      • et al.
      Cost effectiveness of early discharge after uncomplicated acute myocardial infarction.
      • Mark D.B.
      • Sigmon K.
      • Topol E.J.
      • et al.
      Identification of acute myocardial infarction patients suitable for early hospital discharge after aggressive interventional therapy Results from the Thrombolysis and Angioplasty in Acute Myocardial Infarction Registry.
      there remains uncertainty about the optimal timing of discharge after acute myocardial infarction, particularly from a contemporary, population-based perspective. The objectives of this study were to describe decade-long (1995-2005) trends in length of stay after acute myocardial infarction and examine whether declining length of stay was associated with an increased risk of early rehospitalization and postdischarge all-cause mortality among residents of a large metropolitan area in New England.

      Methods

      Data for this study were derived from the Worcester Heart Attack Study.
      • Goldberg R.J.
      • Gore J.M.
      • Alpert J.S.
      • Dalen J.E.
      Recent changes in attack and survival rates of acute myocardial infarction (1975 through 1981) The Worcester Heart Attack Study.
      • Goldberg R.J.
      • Gore J.M.
      • Alpert J.S.
      • Dalen J.E.
      Incidence and case fatality rates of acute myocardial infarction (1975-1984): The Worcester Heart Attack Study.
      • Goldberg R.J.
      • Yarzebski J.
      • Lessard D.
      • Gore J.M.
      A two-decades (1975 to 1995) long experience in the incidence, in-hospital and long-term case-fatality rates of acute myocardial infarction: a community-wide perspective.
      This is an ongoing population-based investigation that is examining long-term trends in the incidence, hospital, and postdischarge case-fatality rates of acute myocardial infarction among residents of the Worcester (MA) metropolitan area hospitalized at all area medical centers. The details of this study have been described previously.
      • Goldberg R.J.
      • Gore J.M.
      • Alpert J.S.
      • Dalen J.E.
      Incidence and case fatality rates of acute myocardial infarction (1975-1984): The Worcester Heart Attack Study.
      • Goldberg R.J.
      • Yarzebski J.
      • Lessard D.
      • Gore J.M.
      A two-decades (1975 to 1995) long experience in the incidence, in-hospital and long-term case-fatality rates of acute myocardial infarction: a community-wide perspective.
      In brief, the medical records of area residents (2000 census estimate=478,000) hospitalized for possible acute myocardial infarction at all area medical centers were individually reviewed and a diagnosis of acute myocardial infarction was validated according to predefined criteria. Patients who developed acute myocardial infarction secondary to an interventional procedure or surgery were excluded from the study sample.
      A total of 4184 patients who satisfied the diagnostic criteria for acute myocardial infarction during the 6 annual periods examined (1995, 1997, 1999, 2001, 2003, 2005), and were discharged alive during the years under study, constituted the population of this report. Patients with a hospital stay longer than 1 month, transfers (in or out of study hospitals), and those undergoing coronary artery bypass graft surgery were excluded due to extremely long average lengths of stay in these patients.

      Data Collection

      Demographic, medical history, and clinical data were abstracted from hospital medical records by trained study physicians and nurses. Information was collected about patients' age, sex, body mass index, comorbidities (eg, hypertension, heart failure, stroke), acute myocardial infarction order (initial vs prior), location (anterior vs inferior/posterior), and type (Q wave vs non-Q wave), hospital treatment approaches, and hospital discharge status. Information also was collected about the occurrence of in-hospital complications including stroke,
      • Saczynski J.S.
      • Spencer F.A.
      • Gore J.M.
      • et al.
      Twenty-year trends in the incidence of stroke complicating acute myocardial infarction: Worcester Heart Attack Study.
      atrial fibrillation,
      • Saczynski J.
      • McManus D.
      • Zhou Z.
      • et al.
      Trends in atrial fibrillation complicating acute myocardial infarction.
      heart failure,
      • Spencer F.A.
      • Meyer T.E.
      • Goldberg R.J.
      • et al.
      Twenty year trends (1975-1995) in the incidence, in-hospital and long-term death rates associated with heart failure complicating acute myocardial infarction: a community-wide perspective.
      and cardiogenic shock.
      • Goldberg R.J.
      • Spencer F.A.
      • Gore J.M.
      • Lessard D.
      • Yarzebski J.
      Thirty-year trends (1975 to 2005) in the magnitude of, management of, and hospital death rates associated with cardiogenic shock in patients with acute myocardial infarction: a population-based perspective.
      Information about the use of DNR orders was collected through the review of hospital records and physicians' progress notes. Survival status after hospital discharge was ascertained through a review of the medical records for additional hospitalizations and statewide and national searches of death records for area residents.

      Data Analysis

      We examined differences in the distribution of selected characteristics in patients with varying lengths of stay using chi-squared tests. We used multivariate logistic regression to examine the association between demographic, clinical, and treatment variables and a length of stay shorter than the median. We controlled for several variables including age, sex, insurance payer status, medical history, acute myocardial infarction-associated characteristics, hospital clinical complications, receipt of effective cardiac medications (eg, beta-blockers, angiotensin-converting enzyme [ACE] inhibitors), and receipt of cardiac procedures (cardiac catheterization or percutaneous revascularization) during the index hospitalization.
      Logistic multivariable regression was used to examine the association between length of stay and postdischarge mortality at 30 days after hospital admission and 90 days after hospital discharge. Logistic regression also was used to examine the association between length of stay and rehospitalization at 7 and 30 days after discharge, controlling for previously described potentially confounding factors. A Cox proportional hazards regression approach was used to examine differences in rehospitalization in the 12 months following hospital discharge according to length of stay while controlling for duration of follow-up and potentially confounding demographic and clinical factors.

      Results

      Length of Hospital Stay

      There have been marked changes in the distribution of length of stay for greater Worcester residents hospitalized with acute myocardial infarction during the period under study (1995-2005) (Figure). The average length of stay decreased by more than 2 days over the 10-year study period from 7.2 days in 1995 to 5.0 days in 2005, corresponding to a 30% overall decrease in length of stay over this period. In 1995, <20% of patients were hospitalized for <5 days compared with approximately 60% of patients in 2005. Extremely long lengths of stay (≥10 days) decreased from nearly one fifth of patients in 1995 to <10% in 2005.
      Figure thumbnail gr1
      FigureTrends in length of stay in patients hospitalized with acute myocardial infarction (The Worcester Heart Attack Study).

      Study Sample Characteristics

      Duration of hospitalization was categorized into 5 strata based on the distribution of our data and based on what was considered to be long and short hospital stays for patients hospitalized with acute myocardial infarction during the period under study. Patients with shorter hospital stays were younger, more likely to be men, and more likely to be enrolled in a health maintenance organization (Table 1). These patients were less likely to have a medical history of selected comorbidities and to present with an ST-segment-elevation myocardial infarction; they were less likely to present with an anterior myocardial infarction. Patients with shorter hospital stays were significantly less likely to develop each of the clinical complications examined and were less likely to have a DNR order compared with patients with longer hospitalizations.
      Table 1Characteristics of Patients with Acute Myocardial Infarction (AMI) According to Length of Hospital Stay (Worcester Heart Attack Study)
      CharacteristicLength of Hospital Stay, DaysP-Value
      <3 (n=428)3-4.9 (n=1429)5-6.9 (n=1131)7-9.9 (n=713)≥10 (n=483)
      Age, years, %
       <6543.937.927.620.121.3
       65-7418.720.222.624.326.7
       75-8420.324.328.735.336.2
       ≥8517.117.621.020.315.7<.001
      Men (%)61.759.753.946.847.0<.001
      Payer (%)
       Private payment1.91.82.01.32.3
       Private insurance2.63.62.62.82.5
       Blue Cross9.66.44.73.75.2
       Medicaid4.03.12.62.54.0
       Medicare36.839.651.457.660.0
       HMO38.938.831.128.422.8
       Other6.36.75.63.73.1<.001
      Medical history (%)
       Hypertension68.265.466.869.472.6.04
       Diabetes36.629.930.435.940.3<.001
       Stroke7.78.68.611.412.7.01
       Heart failure23.620.024.031.431.3<.001
       Angina21.720.023.326.521.3.01
      AMI-associated characteristics (%)
       Initial61.766.462.659.964.0.04
       Q Wave14.224.626.223.327.1<.001
       Anterior12.915.018.922.419.1<.001
       STEMI30.833.429.426.127.5.005
       Do not resuscitate order (%)17.318.919.924.126.7<.001
      Complications during hospitalization (%)
       Cardiogenic shock0.70.71.12.511.2<.001
       Heart failure22.225.836.348.465.0<.001
       Recurrent angina12.217.224.323.732.8<.001
       Stroke0.20.70.82.74.2<.001
       Atrial fibrillation11.511.914.019.428.6<.001
      Therapies (%)
       Aspirin94.693.993.892.892.1.48
       ACE inhibitors58.958.852.756.766.1<.001
       βeta-blockers90.689.086.986.482.0<.001
       Calcium antagonists26.422.129.430.136.9<.001
       Lipid-lowering agents62.256.442.339.038.1<.001
       Thrombolitics2.310.014.212.99.5<.001
      Procedures during hospitalization (%)
       Cardiac catheterization55.647.640.444.950.2<.001
       PTCA43.735.925.227.730.3<.001
      ACE=angiotensin-converting enzyme; HMO=health maintenance organization; PTCA=percutaneous transluminal coronary angioplasty; STEMI=ST-segment-elevation myocardial infarction.
      Patients with shorter lengths of stay were more likely to be treated with beta-blockers and lipid-lowering agents but were less likely to be treated with thrombolytic agents. Patients in the longest length of stay strata (≥10 days) were significantly more likely to be treated with ACE inhibitors than were all other patients. The use of cardiac catheterization was highest among patients at the extremes of length of stay (long and short) compared with those with more intermediate stays, while patients with shorter lengths of stay were more likely to undergo a percutaneous coronary intervention (PCI).
      We also examined whether patient characteristics stratified according to median length of stay were different across the various periods under study (Table 2). The median length of stay was 6 days for patients hospitalized in our initial 2 study years (1995/1997), 5 days for those hospitalized during 1999/2001, and 4 days for those hospitalized during 2003/2005. History of several medical comorbidities, including stroke, heart failure, and diabetes, were significantly associated with longer length of stay only during the most recent study years. In contrast, the associations between length of stay and in-hospital treatment with ACE inhibitors, cardiac catheterization, and PCI were attenuated in later study years. Fewer patients presented with Q-wave and anterior acute myocardial infarctions, whereas a greater proportion of patients presented with ST-segment-elevation myocardial infarctions during the most recent study years. Acute myocardial infarction characteristics did not vary over time according to length of stay.
      Table 2Characteristics of Patients with Acute Myocardial Infarction (AMI) According to Length of Hospital Stay (Worcester Heart Attack Study)
      Characteristic1995/1997 (n=1323)1999/2001 (n=1409)2003/2005 (n=1448)
      Length of StayLength of StayLength of Stay
      <Median≥Median<Median≥Median<Median≥Median
      Age (years)
       <6537.227.138.622.444.421.7
       65-7427.126.919.123.017.419.5
       75-8425.031.023.334.119.833.1
       ≥8510.715.119.120.618.425.7
      Men (%)62.351.258.651.262.347.2
      Medical history (%)
       Angina pectoris24.626.919.724.019.819.1
       Stroke10.510.510.214.19.014.0
       Hypertension55.365.865.269.169.479.4
       Diabetes mellitus29.632.129.232.027.540.3
       Heart failure15.920.920.832.221.632.5
      AMI-associated characteristics (%)
       Initial66.363.265.360.664.762.2
       Q-wave29.432.424.122.118.119.0
       Anterior24.727.515.814.411.012.9
       STEMI24.519.440.337.230.628.8
      Clinical complications (%)
       Heart failure22.042.526.946.223.549.8
       Cardiogenic shock0.33.60.33.91.23.5
       Recurrent angina17.134.616.328.714.223.8
       Atrial fibrillation6.412.810.020.214.225.5
       Stroke0.21.80.62.30.72.2
       Do not resuscitate order10.916.521.226.217.428.7
      Therapies (%)
       Aspirin94.793.592.890.995.194.6
       ACE inhibitors37.847.855.460.968.671.0
       βeta-blockers81.481.587.784.495.394.2
       Calcium antagonists29.631.824.130.619.128.5
       Lipid-lowering agents18.914.255.848.476.771.5
       Thrombolitics20.421.112.510.70.51.4
      Procedures during hospitalization (%)
       Cardiac catheterization26.538.243.844.468.455.5
       PTCA12.516.531.627.156.745.2
      ACE=angiotensin-converting enzyme; PTCA=percutaneous transluminal coronary angioplasty; STEMI=ST-segment-elevation myocardial infarction.

      Factors Associated with Shorter Hospital Stays

      We examined the multivariable-adjusted association between various patient demographic and clinical characteristics with hospital length of stay less than the median (5 days) using logistic regression. Patients aged <65 years were significantly more likely to have shorter hospitalizations compared with older patients (Table 3). Male sex and an uncomplicated hospital stay were associated with shorter lengths of stay. Patients presenting with a non-Q-wave or inferior/posterior acute myocardial infarction, compared with those presenting with a Q-wave or anterior acute myocardial infarction, were significantly more likely to have a hospital stay <5 days. The development of cardiogenic shock and stroke during hospitalization were strongly associated with longer lengths of stay. Compared with patients with Blue Cross/Blue Shield insurance, those who were covered under Medicare were significantly more likely to have a prolonged hospital stay. Length of stay did not vary significantly according to other payment types or treatment with effective cardiac medications or coronary interventional procedures.
      Table 3Factors Associated with Length of Stay Shorter than the Median in Patients Hospitalized with Acute Myocardial Infarction (AMI) in the Full Cohort and in Select Study Years (Worcester Heart Attack Study)
      CharacteristicTotal Cohort (n=4184) Odds Ratio (95% CI)1995/1997 (n=1323) Odds Ratio (95% CI)2003/2005 (n=1448) Odds Ratio (95% CI)
      Age (years)
       65-740.65 (0.53-0.80)0.70 (0.46-1.06)0.51 (0.36-0.73)
       75-840.59 (0.48-0.73)0.52 (0.33-0.82)0.37 (0.26-0.53)
       ≥850.78 (0.60-1.00)0.46 (0.27-0.80)0.49 (0.32-0.75)
      Women0.79 (0.68-0.91)0.73 (0.56-0.94)0.72 (0.56-0.92)
      Medical history
       Angina pectoris0.95 (0.80-1.12)1.19 (0.89-1.59)1.46 (1.08-1.98)
       Stroke0.97 (0.77-1.23)1.15 (0.72-1.85)0.90 (0.60-1.34)
       Hypertension0.94 (0.81-1.10)1.14 (0.88-1.47)1.49 (1.12-1.99)
       Diabetes mellitus0.97 (0.83-1.13)0.97 (0.74-1.26)0.72 (0.55-0.93)
       Heart failure1.03 (0.86-1.23)1.02 (0.72-1.45)1.13 (0.82-1.55)
      AMI associated characteristics
       Initial0.99 (0.85-1.15)1.18 (0.89-1.57)0.84 (0.65-1.10)
       Q-wave0.72 (0.61-0.85)0.84 (0.64-1.12)0.60 (0.43-0.85)
       Anterior0.71 (0.60-0.85)0.96 (0.73-1.27)0.92 (0.63-1.35)
      Clinical complications
       Heart failure0.43 (0.67-0.50)0.42 (0.31-0.55)0.38 (0.30-0.51)
       Cardiogenic shock0.29 (0.16-0.53)0.12 (0.03-0.53)0.52 (0.21-1.30)
       Recurrent angina0.41 (0.35-0.49)0.41 (0.30-0.54)0.39 (0.28-0.53)
       Atrial fibrillation0.75 (0.62-0.91)0.67 (0.43-1.03)0.71 (0.52-1.00)
       Stroke0.31 (0.16-0.62)0.09 (0.01-0.73)0.41 (0.13-1.26)
       Do not resuscitate order0.82 (0.67-1.00)1.16 (0.77-1.73)1.07 (0.76-1.49)
      Payer
       Private payment0.58 (0.34-1.02)1.11 (0.40-3.04)0.52 (0.20-1.32)
       Private insurance0.84 (0.53-1.34)0.42 (0.16-1.12)0.71 (0.36-1.38)
       Medicaid0.70 (0.45-1.11)0.94 (0.36-2.46)0.70 (0.35-1.41)
       Medicare0.59 (0.45-0.79)0.86 (0.42-1.77)0.88 (0.60-1.30)
       HMO0.96 (0.72-1.27)0.85 (0.42-1.73)0.90 (0.61-1.31)
       Other0.98 (0.66-1.43)1.11 (0.46-2.65)0.88 (0.43-1.77)
      Therapies
       Effective cardiac medications1.68 (0.87-3.23)0.73 (0.28-1.92)999.99 (0.01->999.99)
       Any intervention procedures1.04 (0.89-1.21)0.45 (0.34-0.61)1.07 (0.78-1.45)
      CI=confidence interval; HMO=health maintenance organization.
      Note: Respective referent categories=age <65 years, male sex, absence of selected medical history variables, prior AMI, non-Q-wave AMI, inferior or posterior AMI, absence of selected clinical complications, absence of a do not resuscitate order, Blue Cross Blue Shield insurance, not receiving cardiac medications, and not undergoing cardiac procedures. Effective cardiac medications: aspirin, beta-blockers, angiotensin-converting enzyme inhibitors, lipid-lowering agents, and thrombolytics.
      We also examined whether factors associated with shorter length of stay varied during the period under study using multivariable-adjusted logistic regression analyses (Table 3). After adjusting for previously described covariates, demographic factors associated with a length of stay shorter than the median (younger age and male sex) did not differ over these 3 time periods. With the exception of diabetes, which was associated with a longer length of stay in 2003/2005, none of the medical comorbidities were associated with length of stay during the time periods examined. Patients whose hospitalizations were not complicated by the development of heart failure, recurrent angina, or atrial fibrillation were significantly more likely to have a shorter length of stay during all periods under study. In contrast, the associations between the development of cardiogenic shock and stroke with length of stay were attenuated in the most recent study years (Table 3).
      The association between in-hospital cardiac procedures (eg, PCI, cardiac catheterization) and length of stay also was attenuated in later study years (Table 3). Other factors associated with prolonged hospital stays (payer and absence of treatment with effective cardiac medications) did not vary according to the period under study (data not shown).

      Length of Hospital Stay and Post-Discharge Mortality

      We carried out a series of multivariable-adjusted models to examine the association between length of stay and postdischarge all-cause death rates. In these analyses, 5-6.9 days represented the reference category because it contained the median length of stay. We found that very long hospital stays (≥10 days) were associated with a significantly higher risk of dying during the 30 and 90 days postdischarge compared with hospital stays of 5-6.9 days (Table 4). Patients hospitalized for <5 days were no more likely to die in the 30 or 90 days following hospital discharge than were our reference group of patients. The adjusted association between 30- and 90-day mortality and length of stay did not vary according to the presence of DNR orders (data not shown).
      Table 4Likelihood of Dying after Hospital Discharge for AMI According to Length of Stay during Index Hospitalization (Worcester Heart Attack Study)
      Length of Stay, DaysNumber of DeathsPostdischarge Death Rate, %Adjusted OR
      Multivariable Odds of Dying, Model 1
      Adjusted for age, sex, payor status, history of medical comorbidities, AMI-associated characteristics, and occurrence of any acute clinical complications.
      Multivariable Odds of Dying, Model 2
      Adjusted for all variables in the previous model plus in-hospital use of any cardiac medications and coronary intervention procedures.
      30 days after discharge
       <3184.21.36 (0.76-2.42)1.25 (0.70-2.25)
       3-4.9694.81.38 (0.93-2.03)1.28 (0.87-1.89)
       5-6.9514.51.0
      Indicates reference category.
      1.0
      Indicates reference category.
       7-9.9456.31.27 (0.82-1.95)1.38 (0.89-2.12)
       ≥104910.12.38 (1.55-3.65)2.68 (1.74-4.15)
      90 days after discharge
       <3358.21.25 (0.81-1.92)1.18 (0.76-1.82)
       3-4.91268.81.22 (0.91-1.63)1.16 (0.86-1.55)
       5-6.91029.01.01.0
       7-9.910014.01.51 (1.11-2.06)1.67 (1.22-2.29)
       ≥109619.92.53 (1.83-3.50)2.88 (2.07-4.01)
      AMI=acute myocardial infarction; OR=odds ratio.
      low asterisk Adjusted for age, sex, payor status, history of medical comorbidities, AMI-associated characteristics, and occurrence of any acute clinical complications.
      Adjusted for all variables in the previous model plus in-hospital use of any cardiac medications and coronary intervention procedures.
      Indicates reference category.
      When we restricted the sample to patients with uncomplicated myocardial infarctions only (defined as the absence of all in-hospital complications [cardiogenic shock, atrial fibrillation, heart failure, stroke, recurrent angina]), and examined the association between length of stay and postdischarge mortality, findings were similar to those reported in the total study sample. Patients with length of stay shorter than the median were no more likely to die in the 30 or 90 days after discharge than were the reference group who were hospitalized for 5-6 days. Extremely long hospital stays (>10 days) were associated with significantly higher 30-day (odds ratio [OR] 4.33, 95% confidence interval [CI], 1.2-15.9) and 90-day (OR 4.01, 95% CI, 1.7-9.6) mortality.
      We also compared length of stay and postdischarge mortality in older (≥65 years) versus younger patients (<65 years). Similar to findings in the overall sample, both older and younger patients hospitalized for 7 days or longer were significantly more likely to have died in the 30 and 90 days following hospital discharge, although the association was much stronger in younger patients (Table 5).
      Table 5Likelihood of Dying after Hospital Discharge for AMI According to Length of Stay during Index Hospitalization According to Age (Worcester Heart Attack Study)
      Length of Stay, DaysAge, Years
      <65 Multivariable Odds of Dying65+ Multivariable Odds of Dying
      30 days after discharge
       <30.71 (0.6-8.93)1.29 (0.71-2.34)
       3-4.91.25 (0.19-8.19)1.25 (0.84-1.87)
       5-6.91.01.0
       7-9.92.47 (0.31-19.89)1.33 (0.86-2.06)
       ≥106.82 (1.23-41.23)2.24 (1.43-3.49)
      90 days after discharge
       <31.09 (0.21-5.49)1.18 (0.75-1.85)
       3-4.91.95 (0.56-6.89)1.09 (0.81-1.47)
       5-6.91.01.0
       7-9.92.35 (0.53-10.44)1.56 (1.13-2.14)
       ≥106.93 (1.83-26.12)2.43 (1.73-3.42)
      AMI=acute myocardial infarction.
      Adjusted for sex, payor status, history of medical comorbidities, AMI-associated characteristics, occurrence of any acute clinical complications, in-hospital use of any cardiac medications, and coronary intervention procedures.

      Length of Stay and Hospital Readmission

      Hospital readmission data were available only for patients hospitalized with acute myocardial infarction during our 2 most recent study years of 2003 and 2005. During these years, nearly one half (46%) of all patients were rehospitalized for any cause within the ensuing 12 months. Rates of rehospitalization differed according to length of stay during the index hospitalization for acute myocardial infarction. Compared with patients hospitalized for shorter than the median length of stay during 2003 and 2005 (4 days), those who were hospitalized for 4 or more days had lower rates of rehospitalization at 7 days (5.7% vs 5.0%) but higher rates at 1 month (14.5% vs 17.9%), 3 months (24.7% vs 31.0%), and 1 year (41.3% vs 48.4%) after hospital discharge.
      Logistic regression was used to examine the association between length of stay and rehospitalization in the 7 and 30 days after hospital discharge for acute myocardial infarction. After adjusting for several potential confounding variables, the association between length of stay and rehospitalization was attenuated. At both 7 and 30 days postdischarge, the odds of rehospitalization among patients whose index hospitalization was shorter than the median number of days did not differ significantly from those with longer hospital stays (7-day OR 1.28, 95% CI, 0.79-2.08; 30-day OR 0.94, 95% CI, 0.70-1.27). We found similar results when we used a proportional hazards regression analysis to examine the association of length of stay with rehospitalization during the first year after hospital discharge. The odds of rehospitalization after a length of stay shorter than the median did not differ significantly from longer stays (adjusted OR 0.90, 95% CI, 0.74-1.08) and the association did not differ by year (2003 OR 0.91, 95% CI, 0.68-1.19; 2005 OR 0.83, 95% CI, 0.64-1.10).

      Discussion

      The results of this population-based observational study suggest that the average length of stay in patients hospitalized with validated acute myocardial infarction in a large New England community decreased between 1995 and 2005. Additionally, we found that shorter lengths of stay did not adversely affect the risk of hospital readmission 7 and 30 days after hospital discharge or mortality in the 30 and 90 days following discharge.
      A number of studies have shown that, despite the advanced age and greater frequency of comorbidities in patients hospitalized with acute myocardial infarction during recent years, length of stay has decreased significantly over the past 2 decades.
      • Baker D.W.
      • Einstadter D.
      • Husak S.S.
      • Cebul R.D.
      Trends in postdischarge mortality and readmissions: has length of stay declined too far?.
      • Berger A.K.
      • Duval S.
      • Jacobs Jr, D.R.
      • et al.
      Relation of length of hospital stay in acute myocardial infarction to postdischarge mortality.
      • Every N.R.
      • Spertus J.
      • Fihn S.D.
      • Hlatky M.
      • Martin J.S.
      • Weaver W.D.
      Length of hospital stay after acute myocardial infarction in the Myocardial Infarction Triage and Intervention (MITI) Project registry.
      • Sgura F.A.
      • Wright R.S.
      • Kopecky S.L.
      • Grill J.P.
      • Reeder G.S.
      Length of stay in myocardial infarction.
      • Harrison M.L.
      • Graff L.A.
      • Roos N.P.
      • Brownell M.D.
      Discharging patients earlier from Winnipeg hospitals: does it adversely affect quality of care?.
      A study of 8612 Medicare patients in northeast Ohio hospitalized with acute myocardial infarction reported a 25% decrease in average length of stay between 1991 and 1997;
      • Baker D.W.
      • Einstadter D.
      • Husak S.S.
      • Cebul R.D.
      Trends in postdischarge mortality and readmissions: has length of stay declined too far?.
      a recent report on 4458 patients with acute myocardial infarction in Minneapolis-St. Paul, Minnesota, found a more than 50% decrease in the median length of stay between 1985 and 2001.
      • Berger A.K.
      • Duval S.
      • Jacobs Jr, D.R.
      • et al.
      Relation of length of hospital stay in acute myocardial infarction to postdischarge mortality.
      We found a nearly one third decrease in the average and median length of stay over the 10-year period examined in the present study (1995-2005).
      Mortality rates after hospital discharge are a potential indicator of whether or not these decreases in length of stay represent optimal patient care. The 2 large, previously described cohorts of patients hospitalized with acute myocardial infarction have reported on the association between decreasing length of stay and postdischarge mortality with varying results.
      • Baker D.W.
      • Einstadter D.
      • Husak S.S.
      • Cebul R.D.
      Trends in postdischarge mortality and readmissions: has length of stay declined too far?.
      • Berger A.K.
      • Duval S.
      • Jacobs Jr, D.R.
      • et al.
      Relation of length of hospital stay in acute myocardial infarction to postdischarge mortality.
      The northeast Ohio study of Medicare patients reported that the 30-day mortality rate among patients with acute myocardial infarction increased nearly 50% between 1991 and 1997, particularly in patients with early DNR orders.
      • Baker D.W.
      • Einstadter D.
      • Husak S.S.
      • Cebul R.D.
      Trends in postdischarge mortality and readmissions: has length of stay declined too far?.
      In contrast, in the Minnesota Heart Survey, declining length of stay between 1985 and 2001 was not associated with an increased risk of dying in the 6 months after hospital discharge.
      • Berger A.K.
      • Duval S.
      • Jacobs Jr, D.R.
      • et al.
      Relation of length of hospital stay in acute myocardial infarction to postdischarge mortality.
      We found that extended lengths of stay (≥10 days) were associated with a significantly higher risk of dying at 30 and 90 days postdischarge, but that length of stay shorter than the median was not associated with poorer long-term outcomes. In addition, the association between length of stay and postdischarge mortality did not vary according to DNR status in our cohort.
      There has been concern that shorter hospital stays may result in an increased risk of rehospitalization, although several studies reported no change in rehospitalization rates over periods during which lengths of stay decreased significantly.
      • Baker D.W.
      • Einstadter D.
      • Husak S.S.
      • Cebul R.D.
      Trends in postdischarge mortality and readmissions: has length of stay declined too far?.
      • Harrison M.L.
      • Graff L.A.
      • Roos N.P.
      • Brownell M.D.
      Discharging patients earlier from Winnipeg hospitals: does it adversely affect quality of care?.
      Similarly, we found that the adjusted odds of rehospitalization in the year after hospital discharge did not differ significantly by length of stay. Our findings on rehospitalization rates must, however, be interpreted with caution because these data were available only for patients hospitalized for acute myocardial infarction during the 2 most recent years under study (2003 and 2005).
      There are a number of factors that may contribute to declining lengths of stay among patients hospitalized with acute myocardial infarction. These factors include improvements in medical management and the timing of these therapies, changing physician practices, patient preferences, and economic pressures to improve the efficiency of hospitalizations. Several effective cardiac therapies have been shown to be associated with significantly shorter hospital stays,
      • Every N.R.
      • Spertus J.
      • Fihn S.D.
      • Hlatky M.
      • Martin J.S.
      • Weaver W.D.
      Length of hospital stay after acute myocardial infarction in the Myocardial Infarction Triage and Intervention (MITI) Project registry.
      • Sgura F.A.
      • Wright R.S.
      • Kopecky S.L.
      • Grill J.P.
      • Reeder G.S.
      Length of stay in myocardial infarction.
      and increasing use of these therapies over time
      • Goldberg R.J.
      • Spencer F.A.
      • Yarzebski J.
      • et al.
      A 25-year perspective into the changing landscape of patients hospitalized with acute myocardial infarction (the Worcester Heart Attack Study).
      may account, in part, for the declining length of stay of patients that we observed. Similarly, increasing use of PCI in patients with acute myocardial infarction allows for immediate revascularization, identifies other coronary lesions, and may eliminate the need for further in-hospital risk stratification, which would also be expected to decrease length of stay.
      • Floyd K.C.
      • Yarzebski J.
      • Spencer F.A.
      • et al.
      A 30-year perspective (1975-2005) into the changing landscape of patients hospitalized with initial acute myocardial infarction: Worcester Heart Attack Study.

      Study Strengths and Limitations

      The strengths of this study include our population-based design that included all patients hospitalized for acute myocardial infarction from a well-characterized community. All cases of possible acute myocardial infarction were independently validated according to standardized criteria, and we were also able to control for a number of potentially confounding factors. The limitations of this study were that we were unable to examine physician visits and home care services that may have increased as a result of shorter hospital stays. In addition, this cohort consists largely of white patients and thus may lack generalizability to other racial/ethnic groups. While our diagnostic criteria for acute myocardial infarction have remained unchanged during the years under study, it is possible that less severely ill patients may have been hospitalized during more recent study years. Similarly, changing patient demographic and clinical characteristics, other unmeasured variables, as well as the extent of information collected and recorded in hospital medical records, may have changed during the years of this investigation, which may have affected some of the results observed.

      Conclusions

      New classifications of patients at low risk for poor outcomes (eg, uncomplicated acute myocardial infarction) may help identify patients who may benefit from early hospital discharge.
      • Newby K.
      • Califf R.M.
      • Guerci A.
      • et al.
      Early discharge in the thrombolytic era: an analysis of criteria for uncomplicated infarction from the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO) trial.
      The results of this population-based study show that shorter hospital stays are not associated with higher rates of rehospitalization or of postdischarge mortality. However, further studies are needed to identify the optimal length of hospital stay for patients who have experienced an acute myocardial infarction.

      Acknowledgment

      This research was made possible by the cooperation of participating hospitals in the Worcester metropolitan area and through funding provided by the National Institutes of Health ( RO1 HL35434 ).

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