Randomised controlled trial and economic evaluation of a chest pain observation unit compared with routine care
http://www.100md.com
《英国医生杂志》
1 School of Health and Related Research, University of Sheffield, Sheffield S1 4DA, 2 Emergency Department, Northern General Hospital, Sheffield S5 7AU, 3 Department of Cardiology, Northern General Hospital, 4 Department of Public Health, University of Liverpool, Liverpool L69 3GB
Correspondence to: S Goodacre s.goodacre@sheffield.ac.uk
Abstract
Patients with acute chest pain present a common challenge to acute medical services. Rapid and accurate assessment for an acute coronary syndrome is essential,1 yet clinical assessment, electrocardiography, and chest radiography have well recognised limitations.2 Many patients are therefore admitted to hospital for observation.3 Despite this, inadvertent discharge of patients with possible acute coronary syndrome remains common.4 5
The concept of the chest pain observation unit has been developed to address these problems.6 7 Patients with chest pain for which no definite diagnosis has been made after clinical assessment, electrocardiogram, and chest radiograph, receive several hours of observation, electrocardiography, and measurement of biochemical cardiac markers, followed by provocative cardiac testing where appropriate. Patients with positive tests are admitted to hospital, whereas those with negative tests may safely be discharged home. This approach aims to improve care by providing a more rigorous diagnostic assessment while reducing costs to the health service by avoiding unnecessary admissions to hospital.
We aimed to evaluate the effectiveness and cost effectiveness of care in a chest pain observation unit. The specific objectives were to measure the effect of care in the chest pain observation unit on admission to hospital for undifferentiated chest pain, inappropriate discharge home with acute coronary syndrome, health utility, major adverse cardiac events, and reattendance at and readmission to hospital; and to measure the cost effectiveness of care in the chest pain observation unit compared with routine care.
Methods
We randomised 442 days in equal numbers (221 each) to care in the chest pain observation unit and routine care. Screening identified 6957 attendances with chest pain or a related complaint (6% of all attendances to the emergency department). Of these 1631 (23.5%) were potentially eligible for care in the chest pain observation unit, 1118 (16.1%) were asked to participate, and 972 (14%) agreed. Figure 1 shows the CONSORT diagram, and table 1 shows the application of exclusion criteria. The study groups are outlined in table 2. Source of referral, smoking status, and electrocardiogram at presentation showed significant baseline imbalance between the study groups. Hence adjusted analyses included these covariates, along with age, sex, and past history of coronary heart disease.
Fig 1 Flow of participants through the trial
Table 1 Application of each exclusion criterion by group. Values are numbers (percentages) unless otherwise indicated
Table 2 Baseline characteristics of the study groups. Values are numbers (percentages) unless otherwise indicated
The proportion admitted was 36.7% (176/479) of patients receiving care in the chest pain observation unit and 53.8% (265/493) receiving routine care (odds ratio 0.5, 95% confidence interval 0.39 to 0.65, P < 0.001, intraclass correlation coefficient = 0.001). Adjustment for confounding did not alter this result (adjusted odds ratio 0.49, 0.36 to 0.65, P < 0.001). The 146 patients who were eligible for the study but declined to consent were also less likely to be admitted if they attended when the chest pain observation unit was open (22.1% v 40.0%, odds ratio 0.43, P = 0.02).
Seventy patients had a raised concentration of troponin T at follow up (mean concentration 0.65 ng/ml, median concentration 0.29 ng/ml, 57/70 (81.4%) > 0.1 ng/ml). Seven (10%) had been discharged home: 2/34 (5.9%) who received care in the chest pain observation unit and 5/36 (13.9%) who received routine care (difference 8.0%, -7.3% to 23.4%, P = 0.264).
Two participants in each group died during follow up, two from cardiac causes and two from non-cardiac causes. Nine other patients had serious, but non-fatal, cardiac events during follow up (all non-fatal myocardial infarction), four from the group receiving care in the chest pain observation unit and five from the group receiving routine care. Another 24 participants underwent a revascularisation procedure during follow up, which makes a total of 35 patients categorised as having a major adverse cardiac event during follow up (3.6%): 18 (3.8%) from the group receiving care in the chest pain observation unit and 17 (3.4%) from the group receiving routine care (difference 0.4%, -2.0 to 2.7, P = 0.796).
Table 3 shows the EQ-5D scores. The mean area under the curve for health utility was 0.3936 QALYs after care in the chest pain observation unit and 0.3799 QALYs after routine care (difference 0.0137 QALYs, 95% confidence interval 0.0030 to 0.0254, P = 0.022; adjusted difference 0.0143 QALYs, 0.0031 to 0.0255, P = 0.012). The intraclass correlation coefficient was zero for all health utility analyses. The results were robust to sensitivity analysis according to the method of handling missing data.
Table 3 Health utility over six months for groups receiving care in the chest pain observation unit and routine care
Over the six month follow up period, 61 participants (12.7%) in the group receiving care in the chest pain observation unit and 85 (17.2%) in the group receiving routine care reattended the emergency department (odds ratio for reattendance after chest pain observation unit care 0.65, P = 0.05; adjusted odds ratio 0.66, P = 0.061). Over the same time, 37 participants (7.7%) in the chest pain observation unit group and 52 (10.5%) in the routine care group were readmitted to hospital (odds ratio 0.67, P = 0.122; adjusted odds ratio 0.65, P = 0.126).
The mean cost per patient for chest pain related care over six months was ￡478 for the chest pain observation unit group and ￡556 for the routine care group (difference ￡78 per patient, -￡56 to ￡210, P = 0.252; intraclass correlation coefficient = 0.046; adjusted difference ￡53 per patient, -￡88 to +￡194, P = 0.462). Table 4 shows the breakdown of resource use for each group and table 5 shows the breakdown of costs. Higher initial costs for care in the chest pain observation unit were offset by lower costs for hospital admission and follow up.
Table 4 Breakdown of average resource use per patient. Values are numbers (percentages) of patients receiving the intervention unless otherwise indicated
Table 5 Breakdown of costs over six months for groups receiving care in the chest pain observation unit and routine care
Figure 2 shows the cost effect pairs plotted on the cost effectiveness plane.19 Each represents a bootstrap estimate of the difference in mean cost (Y axis) and mean effect (X axis) of care in the chest pain observation unit compared with routine care (positive values indicate that the chest pain observation unit is more effective and more expensive). This shows that, although care in the chest pain observation unit is very likely to be more effective than routine care, considerable uncertainty prevails regarding comparative costs, with the 95% confidence interval including the possibility of the chest pain observation unit being more expensive. However, if we are willing to pay ￡2750 per QALY gained by care in the chest pain observation unit then the probability that the chest pain observation unit will be considered cost effective is 95%.20
Fig 2 Cost effectiveness plane for care in the chest pain observation unit compared with routine care based on 1000 bootstrap estimates of the difference in costs and QALYs. The vertical and horizontal bars indicate the 95% confidence intervals for cost and effect differences. The ellipse indicates the 95% confidence interval for cost effectiveness
Discussion
Department of Health. The national service framework for coronary heart disease. London, DoH, 2000.
Panju AA, Hemmelgarn BR, Guyatt GH, Simel DL. The rational clinical examination. Is this patient having a myocardial infarction? JAMA 1998;280: 1256-63.
Capewell S, McMurray JJV. "Chest pain—please admit," is there an alternative? BMJ 2000;320: 951-2.
Collinson PO, Premachandram S, Hashemi K. Prospective audit of incidence of prognostically important myocardial damage in patients discharged from the emergency department. BMJ 2000;320: 1702-5.
Pope JH, Aufderheide TP, Ruthazer R, Woolard RH, Feldman JA, Beshansky JR, et al. Missed diagnosis of acute cardiac ischaemia in the emergency department. N Engl J Med 2000;342: 1163-70.
Clancy M. Chest pain units. BMJ 2002;325: 116-7.
Goodacre SW. Should we establish chest pain observation units in the United Kingdom? A systematic review and critical appraisal of the literature. J Accid Emerg Med 2000;17: 1-6.
Goodacre S, Morris FP, Campbell S, Angelini K, Arnold J. A prospective, observational study and cost analysis of a chest pain observation unit. Emerg Med J 2002;19: 117-21.
Goldman L, Cook EF, Brand DA, Lee TH, Rouan GW, Weisberg MC, et al. A computer protocol to predict myocardial infarction in emergency department patients with chest pain. N Engl J Med 1988;318: 797-803.
Pozen MW, D'Agostino RB, Selker HP, Sytkowski PA, Hood WB. A predictive instrument to improve coronary-care-unit admission practices in acute ischaemic heart disease. A prospective multicenter study. N Engl J Med 1984;310: 1273-8.
Fesmire FM, Percy RF, Bardoner JB, Wharton DR, Calhoun FB. Usefulness of automated serial 12-lead ECG monitoring during the initial emergency department evaluation of patients with chest pain. Ann Emerg Med 1998;31: 3-11.
Fesmire FM, Percy RF, Bardoner JB, Wharton DR, Calhoun FB. Serial creatinine kinase (CK) MB testing during the emergency department evaluation of chest pain: utility of a 2-hour deltaCK-MB of +1.6ng/ml. Am Heart J 1998;136: 237-44.
Hamm CW, Goldman BW, Heeschen C, Kreymann G, Berger J, Meinertz T. Emergency room triage of patients with acute chest pain by means of rapid testing for cardiac troponin T or troponin I. N Engl J Med 1997;337: 1648-53.
Kirk JD, Turnipseed S, Lewis RL, Amsterdam EA. Evaluation of chest pain in low-risk patients presenting to the emergency department: the role of immediate exercise testing. Ann Emerg Med 1998;32: 1-7.
Ohman EM, Armstrong PW, Christenson RH, Granger CB, Katus HA, Hamm CW, et al. Cardiac troponin T levels for risk stratification in acute myocardial ischaemia. N Engl J Med 1996;335: 1333-41.
Lindahl B, Venge P, Wallentin L. The FRISC experience with troponin T. Use as a decision tool and comparison with other prognostic markers. Eur Heart J 1998;19: N51-58.
Department of Health. National schedule of reference costs. London: DoH, 2002. www.doh.gov.uk/nhsexec/refcosts.htm (accessed 15 Dec 2002).
Netten A, Rees T, Harrison, G. Unit costs of health and social care. Canterbury: Personal Social Services Research Unit, University of Kent, 2001.
Briggs A, Fenn P. Confidence intervals or surfaces? Uncertainty of the cost-effectiveness plane. Health Econ 1998;7: 723-40.
Raftery J. NICE: faster access to modern treatments? Analysis of guidance on health technologies. BMJ 2001;323: 1300-3.
Farkouh ME, Smars PA, Reeder GS, Zinsmeister AR, Evans RW, Meloy TD, et al. A clinical trial of a chest pain observation unit for patients with unstable angina. N Engl J Med 1998;339: 1882-8.
Roberts RR, Zalenski RJ, Mensah EK, Rydman RJ, Ciavarella G, Gussow L, et al. Costs of an emergency department-based accelerated diagnostic protocol vs hospitalization in patients with chest pain. A randomized controlled trial. JAMA 1997;278: 1670-6.
Gomez MA, Anderson JL, Karagounis LA, Muhlestein JB, Mooers FB. An emergency department-based protocol for rapidly ruling out myocardial ischaemia reduces hospital time and expense: results of a randomized study (ROMIO). J Am Coll Cardiol 1996;28: 25-33.
Goodacre S, Nicholl J, Beahan J, Quinney D, Capewell S. National survey of emergency department management of patients with acute, undifferentiated chest pain. Br J Cardiol 2003;10: 50-4.(Steve Goodacre, senior le)
Correspondence to: S Goodacre s.goodacre@sheffield.ac.uk
Abstract
Patients with acute chest pain present a common challenge to acute medical services. Rapid and accurate assessment for an acute coronary syndrome is essential,1 yet clinical assessment, electrocardiography, and chest radiography have well recognised limitations.2 Many patients are therefore admitted to hospital for observation.3 Despite this, inadvertent discharge of patients with possible acute coronary syndrome remains common.4 5
The concept of the chest pain observation unit has been developed to address these problems.6 7 Patients with chest pain for which no definite diagnosis has been made after clinical assessment, electrocardiogram, and chest radiograph, receive several hours of observation, electrocardiography, and measurement of biochemical cardiac markers, followed by provocative cardiac testing where appropriate. Patients with positive tests are admitted to hospital, whereas those with negative tests may safely be discharged home. This approach aims to improve care by providing a more rigorous diagnostic assessment while reducing costs to the health service by avoiding unnecessary admissions to hospital.
We aimed to evaluate the effectiveness and cost effectiveness of care in a chest pain observation unit. The specific objectives were to measure the effect of care in the chest pain observation unit on admission to hospital for undifferentiated chest pain, inappropriate discharge home with acute coronary syndrome, health utility, major adverse cardiac events, and reattendance at and readmission to hospital; and to measure the cost effectiveness of care in the chest pain observation unit compared with routine care.
Methods
We randomised 442 days in equal numbers (221 each) to care in the chest pain observation unit and routine care. Screening identified 6957 attendances with chest pain or a related complaint (6% of all attendances to the emergency department). Of these 1631 (23.5%) were potentially eligible for care in the chest pain observation unit, 1118 (16.1%) were asked to participate, and 972 (14%) agreed. Figure 1 shows the CONSORT diagram, and table 1 shows the application of exclusion criteria. The study groups are outlined in table 2. Source of referral, smoking status, and electrocardiogram at presentation showed significant baseline imbalance between the study groups. Hence adjusted analyses included these covariates, along with age, sex, and past history of coronary heart disease.
Fig 1 Flow of participants through the trial
Table 1 Application of each exclusion criterion by group. Values are numbers (percentages) unless otherwise indicated
Table 2 Baseline characteristics of the study groups. Values are numbers (percentages) unless otherwise indicated
The proportion admitted was 36.7% (176/479) of patients receiving care in the chest pain observation unit and 53.8% (265/493) receiving routine care (odds ratio 0.5, 95% confidence interval 0.39 to 0.65, P < 0.001, intraclass correlation coefficient = 0.001). Adjustment for confounding did not alter this result (adjusted odds ratio 0.49, 0.36 to 0.65, P < 0.001). The 146 patients who were eligible for the study but declined to consent were also less likely to be admitted if they attended when the chest pain observation unit was open (22.1% v 40.0%, odds ratio 0.43, P = 0.02).
Seventy patients had a raised concentration of troponin T at follow up (mean concentration 0.65 ng/ml, median concentration 0.29 ng/ml, 57/70 (81.4%) > 0.1 ng/ml). Seven (10%) had been discharged home: 2/34 (5.9%) who received care in the chest pain observation unit and 5/36 (13.9%) who received routine care (difference 8.0%, -7.3% to 23.4%, P = 0.264).
Two participants in each group died during follow up, two from cardiac causes and two from non-cardiac causes. Nine other patients had serious, but non-fatal, cardiac events during follow up (all non-fatal myocardial infarction), four from the group receiving care in the chest pain observation unit and five from the group receiving routine care. Another 24 participants underwent a revascularisation procedure during follow up, which makes a total of 35 patients categorised as having a major adverse cardiac event during follow up (3.6%): 18 (3.8%) from the group receiving care in the chest pain observation unit and 17 (3.4%) from the group receiving routine care (difference 0.4%, -2.0 to 2.7, P = 0.796).
Table 3 shows the EQ-5D scores. The mean area under the curve for health utility was 0.3936 QALYs after care in the chest pain observation unit and 0.3799 QALYs after routine care (difference 0.0137 QALYs, 95% confidence interval 0.0030 to 0.0254, P = 0.022; adjusted difference 0.0143 QALYs, 0.0031 to 0.0255, P = 0.012). The intraclass correlation coefficient was zero for all health utility analyses. The results were robust to sensitivity analysis according to the method of handling missing data.
Table 3 Health utility over six months for groups receiving care in the chest pain observation unit and routine care
Over the six month follow up period, 61 participants (12.7%) in the group receiving care in the chest pain observation unit and 85 (17.2%) in the group receiving routine care reattended the emergency department (odds ratio for reattendance after chest pain observation unit care 0.65, P = 0.05; adjusted odds ratio 0.66, P = 0.061). Over the same time, 37 participants (7.7%) in the chest pain observation unit group and 52 (10.5%) in the routine care group were readmitted to hospital (odds ratio 0.67, P = 0.122; adjusted odds ratio 0.65, P = 0.126).
The mean cost per patient for chest pain related care over six months was ￡478 for the chest pain observation unit group and ￡556 for the routine care group (difference ￡78 per patient, -￡56 to ￡210, P = 0.252; intraclass correlation coefficient = 0.046; adjusted difference ￡53 per patient, -￡88 to +￡194, P = 0.462). Table 4 shows the breakdown of resource use for each group and table 5 shows the breakdown of costs. Higher initial costs for care in the chest pain observation unit were offset by lower costs for hospital admission and follow up.
Table 4 Breakdown of average resource use per patient. Values are numbers (percentages) of patients receiving the intervention unless otherwise indicated
Table 5 Breakdown of costs over six months for groups receiving care in the chest pain observation unit and routine care
Figure 2 shows the cost effect pairs plotted on the cost effectiveness plane.19 Each represents a bootstrap estimate of the difference in mean cost (Y axis) and mean effect (X axis) of care in the chest pain observation unit compared with routine care (positive values indicate that the chest pain observation unit is more effective and more expensive). This shows that, although care in the chest pain observation unit is very likely to be more effective than routine care, considerable uncertainty prevails regarding comparative costs, with the 95% confidence interval including the possibility of the chest pain observation unit being more expensive. However, if we are willing to pay ￡2750 per QALY gained by care in the chest pain observation unit then the probability that the chest pain observation unit will be considered cost effective is 95%.20
Fig 2 Cost effectiveness plane for care in the chest pain observation unit compared with routine care based on 1000 bootstrap estimates of the difference in costs and QALYs. The vertical and horizontal bars indicate the 95% confidence intervals for cost and effect differences. The ellipse indicates the 95% confidence interval for cost effectiveness
Discussion
Department of Health. The national service framework for coronary heart disease. London, DoH, 2000.
Panju AA, Hemmelgarn BR, Guyatt GH, Simel DL. The rational clinical examination. Is this patient having a myocardial infarction? JAMA 1998;280: 1256-63.
Capewell S, McMurray JJV. "Chest pain—please admit," is there an alternative? BMJ 2000;320: 951-2.
Collinson PO, Premachandram S, Hashemi K. Prospective audit of incidence of prognostically important myocardial damage in patients discharged from the emergency department. BMJ 2000;320: 1702-5.
Pope JH, Aufderheide TP, Ruthazer R, Woolard RH, Feldman JA, Beshansky JR, et al. Missed diagnosis of acute cardiac ischaemia in the emergency department. N Engl J Med 2000;342: 1163-70.
Clancy M. Chest pain units. BMJ 2002;325: 116-7.
Goodacre SW. Should we establish chest pain observation units in the United Kingdom? A systematic review and critical appraisal of the literature. J Accid Emerg Med 2000;17: 1-6.
Goodacre S, Morris FP, Campbell S, Angelini K, Arnold J. A prospective, observational study and cost analysis of a chest pain observation unit. Emerg Med J 2002;19: 117-21.
Goldman L, Cook EF, Brand DA, Lee TH, Rouan GW, Weisberg MC, et al. A computer protocol to predict myocardial infarction in emergency department patients with chest pain. N Engl J Med 1988;318: 797-803.
Pozen MW, D'Agostino RB, Selker HP, Sytkowski PA, Hood WB. A predictive instrument to improve coronary-care-unit admission practices in acute ischaemic heart disease. A prospective multicenter study. N Engl J Med 1984;310: 1273-8.
Fesmire FM, Percy RF, Bardoner JB, Wharton DR, Calhoun FB. Usefulness of automated serial 12-lead ECG monitoring during the initial emergency department evaluation of patients with chest pain. Ann Emerg Med 1998;31: 3-11.
Fesmire FM, Percy RF, Bardoner JB, Wharton DR, Calhoun FB. Serial creatinine kinase (CK) MB testing during the emergency department evaluation of chest pain: utility of a 2-hour deltaCK-MB of +1.6ng/ml. Am Heart J 1998;136: 237-44.
Hamm CW, Goldman BW, Heeschen C, Kreymann G, Berger J, Meinertz T. Emergency room triage of patients with acute chest pain by means of rapid testing for cardiac troponin T or troponin I. N Engl J Med 1997;337: 1648-53.
Kirk JD, Turnipseed S, Lewis RL, Amsterdam EA. Evaluation of chest pain in low-risk patients presenting to the emergency department: the role of immediate exercise testing. Ann Emerg Med 1998;32: 1-7.
Ohman EM, Armstrong PW, Christenson RH, Granger CB, Katus HA, Hamm CW, et al. Cardiac troponin T levels for risk stratification in acute myocardial ischaemia. N Engl J Med 1996;335: 1333-41.
Lindahl B, Venge P, Wallentin L. The FRISC experience with troponin T. Use as a decision tool and comparison with other prognostic markers. Eur Heart J 1998;19: N51-58.
Department of Health. National schedule of reference costs. London: DoH, 2002. www.doh.gov.uk/nhsexec/refcosts.htm (accessed 15 Dec 2002).
Netten A, Rees T, Harrison, G. Unit costs of health and social care. Canterbury: Personal Social Services Research Unit, University of Kent, 2001.
Briggs A, Fenn P. Confidence intervals or surfaces? Uncertainty of the cost-effectiveness plane. Health Econ 1998;7: 723-40.
Raftery J. NICE: faster access to modern treatments? Analysis of guidance on health technologies. BMJ 2001;323: 1300-3.
Farkouh ME, Smars PA, Reeder GS, Zinsmeister AR, Evans RW, Meloy TD, et al. A clinical trial of a chest pain observation unit for patients with unstable angina. N Engl J Med 1998;339: 1882-8.
Roberts RR, Zalenski RJ, Mensah EK, Rydman RJ, Ciavarella G, Gussow L, et al. Costs of an emergency department-based accelerated diagnostic protocol vs hospitalization in patients with chest pain. A randomized controlled trial. JAMA 1997;278: 1670-6.
Gomez MA, Anderson JL, Karagounis LA, Muhlestein JB, Mooers FB. An emergency department-based protocol for rapidly ruling out myocardial ischaemia reduces hospital time and expense: results of a randomized study (ROMIO). J Am Coll Cardiol 1996;28: 25-33.
Goodacre S, Nicholl J, Beahan J, Quinney D, Capewell S. National survey of emergency department management of patients with acute, undifferentiated chest pain. Br J Cardiol 2003;10: 50-4.(Steve Goodacre, senior le)