P-Blocker Therapy in Acute Myocardial Infarction: Evidence for Underutilization in the Elderly JERRYH. GURWITZ,M.D., ROBERTJ. GOLDBERG,Ph.D., ZUOYAOCHEN, M.D., M.P.H., JOELM. GORE,M.D., JOSEPHS. ALPERT,M.D., BOS~O~, /&ssachusetts
PURPOSE To assess the impact of patient age on the ~88 of @blocker therapy in the management of acute myocardial infarction. PATIENTS AND MlYEIOD& The population studied consisted of 4,762 patients hospitalized with validated acpte myocdial infarction in 16 hospitals iu the Worcester, Massachusetts, Standard Metropolitan St&&al Area during the years 1976,1978,1981,1984,1986, and 1988. Logistic regression an&&3 was employed to control for relevant demographic and cliuical variables in evaluatiug the independent effect of patient age asadete rminant of receipt of p-blocker therapy during the hospitalization. RIBUL.T&A consi&ent trend toward reduced use of o-blocker therapy in older patients was demonstrated. After adjustment for demographic and clinical variables (gender; prior history of aneina, hypertdxwio~ or diabetes mellitug myocardial infarction characterieticq complications including congestive heart failure and shoclr; and uae of digoxh~ and diuretics), odds ratioa for receipt of /I-blocker therapy relative to patients less than 66 years of age were 0.61 for those 66 to s4,0.62 for those 65 to 74; 026 for those 75 to 84, and 0.26 for those 86 or older. Amdyses performed for each study year demonstrated results consistent with those for the overall study populatiolL CONCLUSION: The resuh of this popuhttionbased study suggetst that there are substantial opportunities for expanded ~88 of &blocker therapy in elderly patients who have sustained an acute myocardhd infarction.
From the Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts; the Program for the Analysis of Clinical Strategies, Gerontology Division, Brigham and Women’s Hospital and Harvard Medical School; and the Hebrew Rehabilitation Center for Aged Research and Training Institute. Boston, Massachusetts. This project was supported by NHLBI Grant ROl HL-35434 from the National Heart, Lung, and Blood Institute. Bethesda, Maryland. Dr. Gurwitz is the recipient of a Clinical Investigator Award (KOB AGO0510) from the National Institute on Aging, Bethesda, Maryland. Requests for reprints should be addressed to Jerry H. Gurwitz. M.D., Program for the Analysis of Clinical Strategies, Brigham and Women’s Hospital, 221 Long-wood Avenue, 3rd floor, Boston, Massachusetts 02115. Manuscript submitted December 30, 1991, and accepted in revised form June 16, 1992.
I
n contrast to many pharmacotherapeutic interventions used in patients with acute myocardial infarction whose efficacy is unproven or limited to selected patient subgroups (e.g., lidocaine and calcium channel blockers), the benefits of early treatment with p-blocker therapy have been suggested by several large randomized controlled trials [l-3] and by analyses of pooled data from multiple studies [4]. The survival advantages of @-blocker therapy are thought to derive from the antiarrhythmic properties of these agents, prevention of cardiac rupture, and possibly from a reduction in infarct size [5,6]. Although the benefits of p-blocker therapy in acute infarction are accepted by many physicians, we suspect that there is often a reluctance to administer B blockade to certain “high-risk” groups (e.g., the elderly and those with a history of congestive heart failure) during evolving infarction [7]. Ischemic heart disease is the leading cause of death among the elderly [a]. Eighty percent of all deaths due to acute myocardial infarction occur in individuals over the age of 65; of these, 60% occur in patients 75 years of age or older [Q]. The risk of inhospital death for patients with acute myocardial infarction over 75 years of age ranges from 20% to 30% far exceeding that for younger patients [N-12]. These disappointing results underscore the need not only to examine the benefits of new interventional strategies in elderly patients, but also to examine utilization patterns for existing treatments for which benefits have been established. To assess the impact of advancing patient age on the use of p-blocker therapy in acute myocardial infarction, we analyzed data collected as part of an ongoing community-wide study of patients hospitalized with acute myocardial infarction in the 16 hospitals in the Worcester, Massachusetts, metropolitan area during 6 selected years spanning a 14year period (1975 through 1988).
PATIENTSAND METHODS Study hpulation The population studied consisted of patients hospitalized with a primary or secondary discharge diagnosis of acute myocardial infarction (code 410 in the International Classification of Diseases) in the 16 acute general hospitals in the Worcester, Massa-
December 1992 The American Journal of Medicine
Volume 93
605
/T-BLOCKERTHERAPY IN THE ELDERLY / GURWITZ ET AL
chusetts, Standard Metropolitan Statistical Area wasemployed [15]. Variables were selectedfor induring calendaryears 1975,1978,1981,1984,1986, clusion in logistic models basedon univariate assoand 1988[ 13,141.The medical recordsof all patients ciationsand/or the a priori expectationof relevance with dischargediagnosesof acute myocardial in- to the decision to employ p-blocker therapy. The farction from thesehospitals were individually re- following variableswereincluded in theseanalyses: viewed and validated according to preestablished the patient’s age(lessthan 55 years,55to 64 years, diagnosticcriteria. Thesecriteria includeda clinical 65 to 74 years, 75 to 84 years,and greaterthan or history of prolongedchestpain not relieved by rest equalto 85 years)and gender;prior history of angior nitrates; elevation of the serum level of creatine na, hypertension,or diabetesmellitus; myocardial kinase and its isoenxymesubfraction, or of lactic infarction order (initial versusrecurrent); myocardehydrogenase; and serial electrocardiographic dial infarction type (Q wave versus non-Q wave); tracings obtained during hospitalization showing myocardial infarction location (anterior versus ST-segmentchangesor Q waves(or both) typical of inferior/posterior); peak serum creatinekinaselevacute myocardial infarction. Enzyme levels were el; development of various complications at any consideredelevatedif they exceededthe upper lim- time during hospitalization (congestiveheart failit of normal as specified by the laboratory at each ure, shock, atrial fibrillation, ventricular tachycarparticipating hospital during the selected study dia, ventricular fibrillation, and complete heart years.At least two of thesethree criteria neededto block); use of selectedmedical therapies (digoxin be satisfied for inclusion in the study. and diuretics as therapeutic indicators of congestive heart failure); performanceof an exercisetolerData Collection ance test during the hospitalization; and hospital The medical records of patients with validated survival. Final modelswereconstructedby sequenacutemyocardial infarction wereabstractedfor de- tially deleting variablesfrom the initial models on mographic and clinical data, including age, sex, the basisof lack of significant changein the likelimedical history, occurrenceof selectedcomplica- hood ratio. Models were also produced for each tions during hospitalization (e.g.,congestiveheart study year (1975,1978,1981,1984,1986,1988). To failure, cardiogenic shock), myocardial infarction control for the pre-hospitaluse of B-blockertheratype (Q waveor non-Qwave),myocardialinfarction py, an additional model was constructed for paorder (initial or recurrent), infarct location (anteri- tients hospitalizedin 1986and 1988,which excludor or inferior/posterior), peak enzyme levels, and ed patients who had utilized /3 blockers prior to survival status at the time of hospital discharge. hospitalization. The in-hospital use of selectedmedications, including anticoagulants; antiplatelet agents, fl RESULTS blockers,calcium channel blockers (1986and 1988 Trends in @Blocker Utilization Patterns only); digoxin, diuretics; lidocaine; other antiarA total of 4,762 patients with validated acute rhythmic agents;nitrates; and thrombolytic agents myocardial infarction wereidentified over the 6 pe(1986and 1988only), wasalso ascertainedfrom the riods studied.The study populationhad a meanage review of the medical records.Information on pre- of 66.9(& 12.8)years,and 61.4%were male. Of the hospitalization useof medicationswasavailablefor overallstudy population,39.8%(n = 1,897)received study years 1986 and 1988 only. Information on &blocker therapy at sometime during their hospiroute of administration, timing of therapy in the talization for acute myocardial infarction. context of the hospitalization, and duration of therThe proportionsof patients with acutemyocardiapy was not abstractedfrom the medical record. al infarction who received P-blocker therapy for eachof the six study yearsaresummarizedin Table Data Analysis I. An overall comparison among the study years x2 tests wereusedto evaluatedifferencesin pro- revealedsignificant differencesin use (group comportions of acute myocardial infarction patients parison p
PURPOSE To assess the impact of patient age on the ~88 of @blocker therapy in the management of acute myocardial infarction. PATIENTS AND MlYEIOD& The population studied consisted of 4,762 patients hospitalized with validated acpte myocdial infarction in 16 hospitals iu the Worcester, Massachusetts, Standard Metropolitan St&&al Area during the years 1976,1978,1981,1984,1986, and 1988. Logistic regression an&&3 was employed to control for relevant demographic and cliuical variables in evaluatiug the independent effect of patient age asadete rminant of receipt of p-blocker therapy during the hospitalization. RIBUL.T&A consi&ent trend toward reduced use of o-blocker therapy in older patients was demonstrated. After adjustment for demographic and clinical variables (gender; prior history of aneina, hypertdxwio~ or diabetes mellitug myocardial infarction characterieticq complications including congestive heart failure and shoclr; and uae of digoxh~ and diuretics), odds ratioa for receipt of /I-blocker therapy relative to patients less than 66 years of age were 0.61 for those 66 to s4,0.62 for those 65 to 74; 026 for those 75 to 84, and 0.26 for those 86 or older. Amdyses performed for each study year demonstrated results consistent with those for the overall study populatiolL CONCLUSION: The resuh of this popuhttionbased study suggetst that there are substantial opportunities for expanded ~88 of &blocker therapy in elderly patients who have sustained an acute myocardhd infarction.
From the Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts; the Program for the Analysis of Clinical Strategies, Gerontology Division, Brigham and Women’s Hospital and Harvard Medical School; and the Hebrew Rehabilitation Center for Aged Research and Training Institute. Boston, Massachusetts. This project was supported by NHLBI Grant ROl HL-35434 from the National Heart, Lung, and Blood Institute. Bethesda, Maryland. Dr. Gurwitz is the recipient of a Clinical Investigator Award (KOB AGO0510) from the National Institute on Aging, Bethesda, Maryland. Requests for reprints should be addressed to Jerry H. Gurwitz. M.D., Program for the Analysis of Clinical Strategies, Brigham and Women’s Hospital, 221 Long-wood Avenue, 3rd floor, Boston, Massachusetts 02115. Manuscript submitted December 30, 1991, and accepted in revised form June 16, 1992.
I
n contrast to many pharmacotherapeutic interventions used in patients with acute myocardial infarction whose efficacy is unproven or limited to selected patient subgroups (e.g., lidocaine and calcium channel blockers), the benefits of early treatment with p-blocker therapy have been suggested by several large randomized controlled trials [l-3] and by analyses of pooled data from multiple studies [4]. The survival advantages of @-blocker therapy are thought to derive from the antiarrhythmic properties of these agents, prevention of cardiac rupture, and possibly from a reduction in infarct size [5,6]. Although the benefits of p-blocker therapy in acute infarction are accepted by many physicians, we suspect that there is often a reluctance to administer B blockade to certain “high-risk” groups (e.g., the elderly and those with a history of congestive heart failure) during evolving infarction [7]. Ischemic heart disease is the leading cause of death among the elderly [a]. Eighty percent of all deaths due to acute myocardial infarction occur in individuals over the age of 65; of these, 60% occur in patients 75 years of age or older [Q]. The risk of inhospital death for patients with acute myocardial infarction over 75 years of age ranges from 20% to 30% far exceeding that for younger patients [N-12]. These disappointing results underscore the need not only to examine the benefits of new interventional strategies in elderly patients, but also to examine utilization patterns for existing treatments for which benefits have been established. To assess the impact of advancing patient age on the use of p-blocker therapy in acute myocardial infarction, we analyzed data collected as part of an ongoing community-wide study of patients hospitalized with acute myocardial infarction in the 16 hospitals in the Worcester, Massachusetts, metropolitan area during 6 selected years spanning a 14year period (1975 through 1988).
PATIENTSAND METHODS Study hpulation The population studied consisted of patients hospitalized with a primary or secondary discharge diagnosis of acute myocardial infarction (code 410 in the International Classification of Diseases) in the 16 acute general hospitals in the Worcester, Massa-
December 1992 The American Journal of Medicine
Volume 93
605
/T-BLOCKERTHERAPY IN THE ELDERLY / GURWITZ ET AL
chusetts, Standard Metropolitan Statistical Area wasemployed [15]. Variables were selectedfor induring calendaryears 1975,1978,1981,1984,1986, clusion in logistic models basedon univariate assoand 1988[ 13,141.The medical recordsof all patients ciationsand/or the a priori expectationof relevance with dischargediagnosesof acute myocardial in- to the decision to employ p-blocker therapy. The farction from thesehospitals were individually re- following variableswereincluded in theseanalyses: viewed and validated according to preestablished the patient’s age(lessthan 55 years,55to 64 years, diagnosticcriteria. Thesecriteria includeda clinical 65 to 74 years, 75 to 84 years,and greaterthan or history of prolongedchestpain not relieved by rest equalto 85 years)and gender;prior history of angior nitrates; elevation of the serum level of creatine na, hypertension,or diabetesmellitus; myocardial kinase and its isoenxymesubfraction, or of lactic infarction order (initial versusrecurrent); myocardehydrogenase; and serial electrocardiographic dial infarction type (Q wave versus non-Q wave); tracings obtained during hospitalization showing myocardial infarction location (anterior versus ST-segmentchangesor Q waves(or both) typical of inferior/posterior); peak serum creatinekinaselevacute myocardial infarction. Enzyme levels were el; development of various complications at any consideredelevatedif they exceededthe upper lim- time during hospitalization (congestiveheart failit of normal as specified by the laboratory at each ure, shock, atrial fibrillation, ventricular tachycarparticipating hospital during the selected study dia, ventricular fibrillation, and complete heart years.At least two of thesethree criteria neededto block); use of selectedmedical therapies (digoxin be satisfied for inclusion in the study. and diuretics as therapeutic indicators of congestive heart failure); performanceof an exercisetolerData Collection ance test during the hospitalization; and hospital The medical records of patients with validated survival. Final modelswereconstructedby sequenacutemyocardial infarction wereabstractedfor de- tially deleting variablesfrom the initial models on mographic and clinical data, including age, sex, the basisof lack of significant changein the likelimedical history, occurrenceof selectedcomplica- hood ratio. Models were also produced for each tions during hospitalization (e.g.,congestiveheart study year (1975,1978,1981,1984,1986,1988). To failure, cardiogenic shock), myocardial infarction control for the pre-hospitaluse of B-blockertheratype (Q waveor non-Qwave),myocardialinfarction py, an additional model was constructed for paorder (initial or recurrent), infarct location (anteri- tients hospitalizedin 1986and 1988,which excludor or inferior/posterior), peak enzyme levels, and ed patients who had utilized /3 blockers prior to survival status at the time of hospital discharge. hospitalization. The in-hospital use of selectedmedications, including anticoagulants; antiplatelet agents, fl RESULTS blockers,calcium channel blockers (1986and 1988 Trends in @Blocker Utilization Patterns only); digoxin, diuretics; lidocaine; other antiarA total of 4,762 patients with validated acute rhythmic agents;nitrates; and thrombolytic agents myocardial infarction wereidentified over the 6 pe(1986and 1988only), wasalso ascertainedfrom the riods studied.The study populationhad a meanage review of the medical records.Information on pre- of 66.9(& 12.8)years,and 61.4%were male. Of the hospitalization useof medicationswasavailablefor overallstudy population,39.8%(n = 1,897)received study years 1986 and 1988 only. Information on &blocker therapy at sometime during their hospiroute of administration, timing of therapy in the talization for acute myocardial infarction. context of the hospitalization, and duration of therThe proportionsof patients with acutemyocardiapy was not abstractedfrom the medical record. al infarction who received P-blocker therapy for eachof the six study yearsaresummarizedin Table Data Analysis I. An overall comparison among the study years x2 tests wereusedto evaluatedifferencesin pro- revealedsignificant differencesin use (group comportions of acute myocardial infarction patients parison p
