Relation of Smoking Status to Outcomes After Cardiopulmonary Resuscitation for In-Hospital Cardiac Arrest
2014; Elsevier BV; Volume: 114; Issue: 2 Linguagem: Inglês
10.1016/j.amjcard.2014.04.021
ISSN1879-1913
AutoresTanush Gupta, Dhaval Kolte, Sahil Khera, Wilbert S. Aronow, Chandrasekar Palaniswamy, Marjan Mujib, Diwakar Jain, Sachin Sule, Ali Ahmed, Sei Iwai, Paul Eugenio, Seth Lessner, William H. Frishman, Julio A. Panza, Gregg C. Fonarow,
Tópico(s)Mechanical Circulatory Support Devices
ResumoIn-hospital cardiac arrest (IHCA) is common and is associated with poor prognosis. Data on the effect of smoking on outcomes after IHCA are limited. We analyzed the Nationwide Inpatient Sample databases from 2003 to 2011 for all patients aged ≥18 years who underwent cardiopulmonary resuscitation (CPR) for IHCA to examine the differences in survival to hospital discharge and neurologic status between smokers and nonsmokers. Of the 838,464 patients with CPR for IHCA, 116,569 patients (13.9%) were smokers. Smokers were more likely to be younger, Caucasian, and male. They had a greater prevalence of dyslipidemia, coronary artery disease, hypertension, chronic pulmonary disease, obesity, and peripheral vascular disease. Atrial fibrillation, heart failure, and diabetes mellitus with complications were less prevalent in smokers. Smokers were more likely to have a primary diagnosis of acute myocardial infarction (14.8% vs 9.1%, p <0.001) and ventricular tachycardia or ventricular fibrillation as the initial cardiac arrest rhythm (24.3% vs 20.5%, p <0.001). Smokers had a higher rate of survival to hospital discharge compared with nonsmokers (28.2% vs 24.1%, adjusted odds ratio 1.06, 95% confidence interval 1.05 to 1.08, p <0.001). Smokers were less likely to have a poor neurologic status after IHCA compared with nonsmokers (3.5% vs 3.9%, adjusted odds ratio 0.92, 95% confidence interval 0.89 to 0.95, p <0.001). In conclusion, among patients aged ≥18 years who underwent CPR for IHCA, we observed a higher rate of survival in smokers than nonsmokers—consistent with the "smoker's paradox." Smokers were also less likely to have a poor neurologic status after IHCA. In-hospital cardiac arrest (IHCA) is common and is associated with poor prognosis. Data on the effect of smoking on outcomes after IHCA are limited. We analyzed the Nationwide Inpatient Sample databases from 2003 to 2011 for all patients aged ≥18 years who underwent cardiopulmonary resuscitation (CPR) for IHCA to examine the differences in survival to hospital discharge and neurologic status between smokers and nonsmokers. Of the 838,464 patients with CPR for IHCA, 116,569 patients (13.9%) were smokers. Smokers were more likely to be younger, Caucasian, and male. They had a greater prevalence of dyslipidemia, coronary artery disease, hypertension, chronic pulmonary disease, obesity, and peripheral vascular disease. Atrial fibrillation, heart failure, and diabetes mellitus with complications were less prevalent in smokers. Smokers were more likely to have a primary diagnosis of acute myocardial infarction (14.8% vs 9.1%, p <0.001) and ventricular tachycardia or ventricular fibrillation as the initial cardiac arrest rhythm (24.3% vs 20.5%, p <0.001). Smokers had a higher rate of survival to hospital discharge compared with nonsmokers (28.2% vs 24.1%, adjusted odds ratio 1.06, 95% confidence interval 1.05 to 1.08, p <0.001). Smokers were less likely to have a poor neurologic status after IHCA compared with nonsmokers (3.5% vs 3.9%, adjusted odds ratio 0.92, 95% confidence interval 0.89 to 0.95, p <0.001). In conclusion, among patients aged ≥18 years who underwent CPR for IHCA, we observed a higher rate of survival in smokers than nonsmokers—consistent with the "smoker's paradox." Smokers were also less likely to have a poor neurologic status after IHCA. Smoking is the leading preventable cause of morbidity and mortality in the United States.1Ockene I.S. Miller N.H. Cigarette smoking, cardiovascular disease, and stroke: a statement for healthcare professionals from the American Heart Association. American Heart Association Task Force on Risk Reduction.Circulation. 1997; 96: 3243-3247Crossref PubMed Scopus (390) Google Scholar Although cigarette smokers have higher rates of acute myocardial infarction (AMI) than nonsmokers, multiple studies have shown a lower mortality rate after AMI in smokers.2Kelly T.L. Gilpin E. Ahnve S. Henning H. Ross Jr., J. Smoking status at the time of acute myocardial infarction and subsequent prognosis.Am Heart J. 1985; 110: 535-541Abstract Full Text PDF PubMed Scopus (99) Google Scholar, 3Gourlay S.G. Rundle A.C. Barron H.V. Smoking and mortality following acute myocardial infarction: results from the National Registry of Myocardial Infarction 2 (NRMI 2).Nicotine Tob Res. 2002; 4: 101-107Crossref PubMed Scopus (71) Google Scholar This phenomenon, termed the "smoker's paradox,"4Aune E. Roislien J. Mathisen M. Thelle D.S. Otterstad J.E. The "smoker's paradox" in patients with acute coronary syndrome: a systematic review.BMC Med. 2011; 9: 97Crossref PubMed Scopus (103) Google Scholar, 5Helmers C. Short and long-term prognostic indices in acute myocardial infarction. A study of 606 patients initially treated in a coronary care unit.Acta Med Scand Suppl. 1973; 555: 7-26PubMed Google Scholar has largely been attributed to younger age of and fewer co-morbidities in smokers.6Barbash G.I. Reiner J. White H.D. Wilcox R.G. Armstrong P.W. Sadowski Z. Morris D. Aylward P. Woodlief L.H. Topol E.J. Evaluation of paradoxic beneficial effects of smoking in patients receiving thrombolytic therapy for acute myocardial infarction: mechanism of the "smoker's paradox" from the GUSTO-I trial, with angiographic insights. Global Utilization of Streptokinase and Tissue-Plasminogen Activator for Occluded Coronary Arteries.J Am Coll Cardiol. 1995; 26: 1222-1229Abstract Full Text PDF PubMed Scopus (218) Google Scholar, 7Grines C.L. Topol E.J. O'Neill W.W. George B.S. Kereiakes D. Phillips H.R. Leimberger J.D. Woodlief L.H. Califf R.M. Effect of cigarette smoking on outcome after thrombolytic therapy for myocardial infarction.Circulation. 1995; 91: 298-303Crossref PubMed Google Scholar However, some studies have shown that the association between smoking and improved survival after AMI persists even after adjustment for these variables.8Barbash G.I. White H.D. Modan M. Diaz R. Hampton J.R. Heikkila J. Kristinsson A. Moulopoulos S. Paolasso E.A. Van der Werf T. Perhrsson K. Sandoe E. Simes J. Wilcox R.G. Verstraete M. Von der Lippe G. Van de Werf F. Acute myocardial infarction in the young—the role of smoking. The Investigators of the International Tissue Plasminogen Activator/Streptokinase Mortality Trial.Eur Heart J. 1995; 16: 313-316PubMed Google Scholar, 9Kirtane A.J. Martinezclark P. Rahman A.M. Ray K.K. Karmpaliotis D. Murphy S.A. Giugliano R.P. Cannon C.P. Antman E.M. Roe M.T. Harrington R.A. Ohman E.M. Braunwald E. Gibson C.M. Association of smoking with improved myocardial perfusion and the angiographic characterization of myocardial tissue perfusion after fibrinolytic therapy for ST-segment elevation myocardial infarction.J Am Coll Cardiol. 2005; 45: 321-323Abstract Full Text Full Text PDF PubMed Scopus (27) Google Scholar Smoking has also been found to be associated with lower risk-adjusted in-hospital mortality in patients with acute heart failure and patients with acute ischemic stroke.10Ali S.F. Smith E.E. Bhatt D.L. Fonarow G.C. Schwamm L.H. Paradoxical association of smoking with in-hospital mortality among patients admitted with acute ischemic stroke.J Am Heart Assoc. 2013; 2: e000171Crossref Scopus (3) Google Scholar, 11Fonarow G.C. Abraham W.T. Albert N.M. Stough W.G. Gheorghiade M. Greenberg B.H. O'Connor C.M. Nunez E. Yancy C.W. Young J.B. A smoker's paradox in patients hospitalized for heart failure: findings from OPTIMIZE-HF.Eur Heart J. 2008; 29: 1983-1991Crossref PubMed Scopus (47) Google Scholar Although smoking is a well-defined risk factor for cardiac arrest,12Jouven X. Desnos M. Guerot C. Ducimetiere P. Predicting sudden death in the population: the Paris Prospective Study I.Circulation. 1999; 99: 1978-1983Crossref PubMed Scopus (535) Google Scholar data on the effect of smoking on outcomes after in-hospital cardiac arrest (IHCA) are limited. Given potential physiological similarities of IHCA with AMI, acute heart failure, and acute ischemic stroke, it is possible that a history of smoking may be associated with improved outcomes after cardiopulmonary resuscitation (CPR) of IHCA. The primary objective of this study was to examine the association of smoking status with outcomes after IHCA using the Nationwide Inpatient Sample databases from 2003 to 2011.MethodsData were obtained from the 2003 to 2011 Nationwide Inpatient Sample databases. The Nationwide Inpatient Sample, sponsored by the Agency for Healthcare Research and Quality as a part of Healthcare Cost and Utilization Project, is the largest publicly available all-payer inpatient care database in the United States. It contains discharge-level data from approximately 8 million hospital stays from about 1,000 hospitals designed to approximate a 20% stratified sample of all community hospitals in the United States. Criteria used for stratified sampling of hospitals include hospital ownership, patient volume, teaching status, urban or rural location, and geographic region. Discharge weights are provided for each patient discharge record, which were used to obtain national estimates.We used the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes 99.60 or 99.63 to identify all patients aged ≥18 years who underwent CPR for IHCA (n = 838,464; Figure 1). This approach has been used in previous studies using administrative databases to accurately identify patients with IHCA.13Ehlenbach W.J. Barnato A.E. Curtis J.R. Kreuter W. Koepsell T.D. Deyo R.A. Stapleton R.D. Epidemiologic study of in-hospital cardiopulmonary resuscitation in the elderly.N Engl J Med. 2009; 361: 22-31Crossref PubMed Scopus (280) Google Scholar, 14Kumar G. Nanchal R. Trends in survival after in-hospital cardiac arrest.N Engl J Med. 2013; 368: 680-681Crossref PubMed Scopus (14) Google Scholar Smokers were then identified using ICD-9-CM codes V15.82 or 305.1 (n = 116,569). Patients who did not have either of these ICD-9-CM codes were considered as nonsmokers (n = 721,895). Previous study has shown that these ICD-9-CM codes have a sensitivity of 100%, a specificity of 32%, and an accuracy of 66% to identify smokers in a general patient population with little evidence of documentation bias.15Wiley L.K. Shah A. Xu H. Bush W.S. ICD-9 tobacco use codes are effective identifiers of smoking status.J Am Med Inform Assoc. 2013; 20: 652-658Crossref PubMed Scopus (100) Google ScholarOur primary outcome of interest for this study was survival to hospital discharge. We used poor neurologic status (defined as coma [ICD-9-CM code 780.01], persistent vegetative state [ICD-9-CM code 780.03], or brain death [ICD-9-CM code 348.82]) as the secondary outcome.Baseline patient characteristics used included demographics (age, gender, and race), primary expected payer, weekday versus weekend admission, median household income for patient's zip code, 29 Elixhauser co-morbidities as defined by the Agency for Healthcare Research and Quality, other clinically relevant co-morbidities (dyslipidemia, known coronary artery disease, family history of coronary artery disease, previous myocardial infarction, previous transient ischemic attack or stroke, previous percutaneous coronary angioplasty, previous coronary artery bypass grafting, previous cardiac arrest, family history of sudden cardiac death, carotid artery disease, dementia, and atrial fibrillation), primary diagnosis of AMI, and initial cardiac arrest rhythm.16Elixhauser A. Steiner C. Harris D.R. Coffey R.M. Comorbidity measures for use with administrative data.Med Care. 1998; 36: 8-27Crossref PubMed Scopus (6473) Google Scholar, 17HCUP-USTools & Software Page. Available at: http://www.hcup-us.ahrq.gov/toolssoftware/comorbidity/comorbidity.jsp [Accessed and cited February 27, 2014].Google Scholar A list of ICD-9-CM and Clinical Classifications Software codes used to identify co-morbidities is provided in Supplementary Table 1. Hospital characteristics such as hospital region (Northeast, Midwest, South, and West), number of beds (small, medium, and large), location (rural and urban), and teaching status were also included.We initially compared baseline patient and hospital characteristics between the 2 groups using Pearson's chi-square test for categorical variables and Student t test for continuous variables to identify significant univariate associations. Multivariate logistic regression was used to compare outcomes between the 2 groups. The regression model adjusted for demographics, primary expected payer, weekday versus weekend admission, median household income, all Elixhauser co-morbidities, other clinically relevant co-morbidities (dyslipidemia, known coronary artery disease, family history of coronary artery disease, previous myocardial infarction, previous transient ischemic attack or stroke, previous percutaneous coronary angioplasty, previous coronary artery bypass grafting, previous cardiac arrest, family history of sudden cardiac death, carotid artery disease, dementia, and atrial fibrillation), primary diagnosis of AMI, and initial cardiac arrest rhythm.Statistical analysis was performed using IBM SPSS Statistics 20.0 (IBM Corp., Armonk, New York). We used a 2-sided p value of <0.05 to assess for statistical significance for all analyses. Categorical variables are expressed as percentage and continuous variables as mean ± SD. Odds ratio (OR) and 95% confidence interval (CI) are used to report the results of logistic regression.ResultsFrom 2003 to 2011, of the 838,464 patients with CPR for IHCA, 116,569 patients (13.9%) were smokers. Smokers were more likely to be younger, Caucasian, and male (p <0.001). They were also more likely to have dyslipidemia, coronary artery disease, family history of coronary artery disease, previous myocardial infarction, previous transient ischemic attack or stroke, previous percutaneous coronary angioplasty, previous coronary artery bypass grafting, previous cardiac arrest, alcohol abuse, deficiency anemia, chronic blood loss anemia, chronic pulmonary disease, depression, drug abuse, hypertension, liver disease, metastatic cancer, obesity, peripheral vascular disease, psychoses, pulmonary circulation disorders, and solid tumor without metastasis (p <0.001 for all). Dementia, atrial fibrillation, heart failure, coagulopathy, diabetes mellitus with complications, hypothyroidism, lymphoma, fluid and electrolyte disorder, other neurologic disorders, paralysis, chronic renal failure, valvular disease, and weight loss were less prevalent in smokers (p <0.001 for all). Smokers were more likely to be admitted to large nonteaching hospitals (p <0.001). They were also more likely to have a primary diagnosis of AMI and ventricular tachycardia or fibrillation as the cardiac arrest rhythm (Table 1).Table 1Baseline demographics, co-morbidities, and hospital characteristics of patients ≥18 years of age with in-hospital cardiac arrestVariableNon-SmokersSmokersp Value(n = 721,895)(n = 116,569)Age, mean ± standard deviation (years)67.8 ± 16.363.7 ± 14.2<0.001Women46.9%36.2%<0.001Caucasian62.6%72.8%<0.001African-American20.7%15.8%Hispanic10.1%6.8%Asian or Pacific Islander3.3%2.0%Other3.3%2.6%Primary expected payer<0.001 Medicare65.8%55.3% Medicaid9.8%11.9% Private insurance17.6%21.8% Uninsured4.8%8.0% Other2.0%3.1%Weekend admission23.7%23.9%0.207Median household income (percentile)<0.001 0–25th31.3%30.7% 26th–50th25.6%26.9% 51st–75th23.1%24.5% 76th–100th20.0%17.9%Co-morbidities∗Co-morbidities (including the 29 Elixhauser co-morbidities) were extracted from the database using International Classification of Diseases, Ninth Edition, Clinical Modification diagnosis or Clinical Classification Software codes. Dyslipidemia15.8%28.7%<0.001 Coronary artery disease25.6%36.1%<0.001 Family history of coronary artery disease0.5%2.7%<0.001 Prior myocardial infarction4.8%9.3%<0.001 Prior transient ischemic attack/stroke1.9%3.8%<0.001 Prior percutaneous coronary intervention2.8%6.9%<0.001 Prior coronary bypass5.2%7.4%<0.001 Prior cardiac arrest0.2%0.5%<0.001 Family history of sudden cardiac death<0.1%<0.1%0.140 Carotid artery disease0.8%1.5%<0.001 Dementia6.5%3.4%<0.001 Atrial fibrillation23.5%19.6%<0.001 AIDS0.3%0.4%0.010 Alcohol abuse4.2%12.2%<0.001 Deficiency anemia20.5%21.4%<0.001 Rheumatoid arthritis/collagen vascular diseases2.4%2.3%0.829 Chronic blood loss anemia2.0%1.6%<0.001 Congestive heart failure36.3%30.6%<0.001 Chronic pulmonary disease23.0%42.0%<0.001 Coagulopathy13.5%11.6%<0.001 Depression5.0%8.1%<0.001 Diabetes mellitus (uncomplicated)22.1%22.4%0.077 Diabetes mellitus (complicated)7.8%5.2%<0.001 Drug abuse2.3%6.4%<0.001 Hypertension49.2%56.4%<0.001 Hypothyroidism8.5%8.3%0.009 Liver disease4.1%5.3%<0.001 Lymphoma1.4%1.0%<0.001 Fluid and electrolyte disorder48.7%45.9%<0.001 Metastatic cancer3.8%4.7%<0.001 Other neurological disorders11.5%9.5%<0.001 Obesity7.5%11.2%<0.001 Paralysis3.7%2.3%<0.001 Peripheral vascular disease9.1%13.6%<0.001 Psychoses3.1%4.5%<0.001 Pulmonary circulation disorders4.7%5.5%<0.001 Renal failure (chronic)24.8%17.3%<0.001 Solid tumor without metastasis2.9%4.2%<0.001 Peptic ulcer (non-bleeding)<0.1%<0.1%0.533 Valvular disease5.9%4.8%<0.001 Weight loss10.2%8.8%<0.001Hospital characteristics Number of beds†Number of beds categories are specific to hospital location and teaching status, available at http://www.hcup-us.ahrq.gov/db/vars/hosp_bedsize/nisnote.jsp.<0.001Small10.0%9.2%Medium24.7%23.9%Large65.3%66.9% Urban location90.7%90.5%0.111 Teaching hospital44.7%41.5%<0.001 Region<0.001Northeast20.3%13.2%Midwest18.8%20.7%South37.6%38.6%West23.3%25.5%Ventricular tachycardia/fibrillation20.5%24.3%<0.001Primary diagnosis of acute myocardial infarction9.1%14.8%<0.001AIDS = acquired immunodeficiency syndrome.∗ Co-morbidities (including the 29 Elixhauser co-morbidities) were extracted from the database using International Classification of Diseases, Ninth Edition, Clinical Modification diagnosis or Clinical Classification Software codes.† Number of beds categories are specific to hospital location and teaching status, available at http://www.hcup-us.ahrq.gov/db/vars/hosp_bedsize/nisnote.jsp. Open table in a new tab The primary outcome of the study was survival to hospital discharge. Smokers had a higher rate of survival to hospital discharge after IHCA than nonsmokers (28.2% vs 24.1%, unadjusted OR 1.24, 95% CI 1.22 to 1.26, p <0.001). Survival to hospital discharge remained significantly higher in smokers even after adjusting for baseline demographics, hospital characteristics, co-morbidities, primary diagnosis of AMI, and the initial cardiac arrest rhythm (adjusted OR 1.06, 95% CI 1.05 to 1.08, p <0.001; Table 2).Table 2Outcomes after in-hospital cardiac arrest in non-smokers and smokersOutcomeNon-SmokersSmokersp ValueOdds Ratio (95% CI)UnadjustedAdjusted∗Adjusted for age, sex, race, primary payer status, weekday versus weekend admission, median household income, hospital characteristics (bed size, location, teaching status, and region), co-morbidities, primary diagnosis of acute myocardial infarction, and ventricular tachycardia or fibrillation as the cardiac arrest rhythm.Survival to hospital discharge24.1%28.2%<0.0011.24 (1.22–1.26)1.06 (1.05–1.08)Poor neurological status3.9%3.5%<0.0010.88 (0.85–0.91)0.92 (0.89–0.95)CI = confidence interval.∗ Adjusted for age, sex, race, primary payer status, weekday versus weekend admission, median household income, hospital characteristics (bed size, location, teaching status, and region), co-morbidities, primary diagnosis of acute myocardial infarction, and ventricular tachycardia or fibrillation as the cardiac arrest rhythm. Open table in a new tab Poor neurologic status was used as the secondary outcome of interest. Smokers had a significantly lower rate of poor neurologic status after IHCA compared with nonsmokers (3.5% vs 3.9%, unadjusted OR 0.88, 95% CI 0.85 to 0.91, p <0.001). When adjusted for baseline demographics, hospital characteristics, co-morbidities, primary diagnosis of AMI, and the initial cardiac arrest rhythm, smoking status was associated with a significantly lower likelihood of having a poor neurologic status after IHCA (adjusted OR 0.92, 95% CI 0.89 to 0.95, p 25 years ago after observations that despite the increased prevalence of acute coronary syndromes, the mortality rate after AMI was lower in smokers than in nonsmokers.2Kelly T.L. Gilpin E. Ahnve S. Henning H. Ross Jr., J. Smoking status at the time of acute myocardial infarction and subsequent prognosis.Am Heart J. 1985; 110: 535-541Abstract Full Text PDF PubMed Scopus (99) Google Scholar, 18Sparrow D. Dawber T.R. The influence of cigarette smoking on prognosis after a first myocardial infarction. A report from the Framingham study.J Chronic Dis. 1978; 31: 425-432Abstract Full Text PDF PubMed Scopus (146) Google Scholar This was partly explained by the younger age and fewer co-morbidities in patients with AMI who were current smokers. The magnitude of this paradoxical associated protective effect of smoking was reduced after adjustment for age and co-morbidities; however, some of these studies showed an independent residual association even after adjustment for these factors. Similar results were later replicated in randomized control trials such as the International Tissue Plasminogen Activator/Streptokinase Mortality Trial19Barbash G.I. White H.D. Modan M. Diaz R. Hampton J.R. Heikkila J. Kristinsson A. Moulopoulos S. Paolasso E.A. Van der Werf T. Perhrsson K. Sandoe E. Simes J. Wilcox R.G. Verstraete M. Von der Lippe G. Van de Werf F. Significance of smoking in patients receiving thrombolytic therapy for acute myocardial infarction. Experience gleaned from the International Tissue Plasminogen Activator/Streptokinase Mortality Trial.Circulation. 1993; 87: 53-58Crossref PubMed Scopus (167) Google Scholar and the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries trial.6Barbash G.I. Reiner J. White H.D. Wilcox R.G. Armstrong P.W. Sadowski Z. Morris D. Aylward P. Woodlief L.H. Topol E.J. Evaluation of paradoxic beneficial effects of smoking in patients receiving thrombolytic therapy for acute myocardial infarction: mechanism of the "smoker's paradox" from the GUSTO-I trial, with angiographic insights. Global Utilization of Streptokinase and Tissue-Plasminogen Activator for Occluded Coronary Arteries.J Am Coll Cardiol. 1995; 26: 1222-1229Abstract Full Text PDF PubMed Scopus (218) Google Scholar In an analysis of 297,458 patients with AMI included in the National Registry of Myocardial Infarction 2, crude in-hospital mortality rate among smokers was 50% lower than in nonsmokers. Smokers were on average 14 years younger than nonsmokers. The mortality rate in smokers was lower by 14% even after adjustment for age and baseline clinical risk factors.3Gourlay S.G. Rundle A.C. Barron H.V. Smoking and mortality following acute myocardial infarction: results from the National Registry of Myocardial Infarction 2 (NRMI 2).Nicotine Tob Res. 2002; 4: 101-107Crossref PubMed Scopus (71) Google Scholar Multiple other observational studies and registry analyses have supported the existence of this paradox in patients with AMI.4Aune E. Roislien J. Mathisen M. Thelle D.S. Otterstad J.E. The "smoker's paradox" in patients with acute coronary syndrome: a systematic review.BMC Med. 2011; 9: 97Crossref PubMed Scopus (103) Google Scholar In addition, analyses have found similar associations of smoking status with improved outcomes in patients hospitalized with acute heart failure and patients with acute ischemic stroke.10Ali S.F. Smith E.E. Bhatt D.L. Fonarow G.C. Schwamm L.H. Paradoxical association of smoking with in-hospital mortality among patients admitted with acute ischemic stroke.J Am Heart Assoc. 2013; 2: e000171Crossref Scopus (3) Google Scholar, 11Fonarow G.C. Abraham W.T. Albert N.M. Stough W.G. Gheorghiade M. Greenberg B.H. O'Connor C.M. Nunez E. Yancy C.W. Young J.B. A smoker's paradox in patients hospitalized for heart failure: findings from OPTIMIZE-HF.Eur Heart J. 2008; 29: 1983-1991Crossref PubMed Scopus (47) Google ScholarOur current analysis of a large, contemporary, real-world, multi-institutional cohort of patients included in the Nationwide Inpatient Sample database is the largest study to date to examine the effect of smoking status on outcomes after IHCA. Despite being younger, smokers had greater prevalence of previous myocardial infarction and cardiac arrest and were more likely to have undergone coronary reperfusion in the past. They were also more likely to have AMI at the time of admission to the hospital and have ventricular tachycardia or fibrillation at the time of IHCA. Although the higher survival rate after CPR for IHCA in smokers was partly attenuated after adjustment for baseline differences, there was a residual association even after risk adjustment. Smokers also had significantly lower rates of poor neurologic status after IHCA.Our results are consistent with a recent, single-center observational study that assessed the association between smoking and survival with a good neurologic outcome in 181 patients with cardiac arrest treated with mild therapeutic hypothermia. Smokers had higher survival to hospital discharge with good neurologic outcome compared with nonsmokers (50% vs 28%, p = 0.003). Even after adjustment for age, initial rhythm, time to return of spontaneous circulation, bystander CPR, and time to initiation of therapeutic hypothermia, a history of smoking was independently associated with increased odds of neurologically intact survival at the time of hospital discharge (OR 3.54, 95% CI 1.41 to 8.84, p <0.01).20Pollock J.S. Hollenbeck R.D. Wang L. Janz D.R. Rice T.W. McPherson J.A. 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