REVIEW ER 'S CONCLUSIONS Quitting smoking is associated with a substantial reduction in risk of all-cause mortality among patients with CHD .
This 36 % risk reduction appears substantial compared with other secondary preventive therapies such as cholesterol lowering which have received greater attention in recent years .
The risk reduction associated with quitting smoking seems consistent regardless of differences between the studies in terms of index cardiac events , age , sex , country , and time period .
BACKGROUND Although the importance of smoking as a risk factor for coronary heart disease is beyond doubt , the speed and magnitude of risk reduction when a smoker with coronary heart disease quits are still subjects of debate .
OBJECTIVES To estimate the magnitude of risk reduction when a patient with CHD stops smoking .
Smoking Status and Risk for Recurrent Coronary Events after Myocardial Infarction
Background Smoking cessation decreases the risk for myocardial infa rct ion among people without previous coronary disease , but its effect on risk reduction after a first myocardial infa rct ion has not been well studied . Contribution The research ers retrospectively observed relative risk for recurrent coronary events in patients discharged from the hospital after an incident myocardial infa rct ion . Compared to nonsmokers , active smokers were 1.5 times more likely to have reinfa rct ion . Among persons who had stopped smoking , relative risk decreased gradually to the nonsmokers ' level over 36 months . Implication s Physicians should emphasize the proven benefits of smoking cessation to encourage patients to quit after a first myocardial infa rct ion . The Editors Smoking is a risk factor for coronary artery disease ( 1 ) . Among persons without coronary disease who quit smoking , the risk for incident coronary disease decreases and approaches that of nonsmokers within 2 to 3 years after cessation ( 2 , 3 ) . Some studies ( 4 - 17 ) show that quitting smoking after myocardial infa rct ion also seems to reduce the risk for adverse outcomes , including death . However , these studies of persons with established disease generally focused on men 65 years of age or younger , had limited information about possible confounding factors , did not evaluate the time course of the potential benefits of smoking cessation , and did not compare results to those in nonsmokers . In contrast to these studies showing a benefit of smoking cessation after myocardial infa rct ion , some evidence suggests that after infa rct ion , smokers may not have an elevated risk for recurrent events compared with never-smokers , a finding termed the smoker 's paradox ( 18 - 24 ) . We examined the association between smoking status and risk for recurrent coronary events and explored the time course of potential benefits of cessation in a large population -based inception cohort of persons who survived to hospital discharge after an incident myocardial infa rct ion . Methods Setting and Participants The study setting was Group Health Cooperative ( GHC ) , a health maintenance organization with more than 500 000 enrollees , based in western Washington State . The organization 's model of health care delivery is structured so that most routine care for enrollees , including care after myocardial infa rct ion , is provided by personal primary care physicians . Group Health Cooperative employs more than 300 primary care physicians and contracts with more than 500 other physicians . Eligible patients included all GHC enrollees who survived to hospital discharge after a first myocardial infa rct ion during the period from July 1986 ( women ) or July 1989 ( men ) through December 1996 . Patients with incident myocardial infa rct ion were identified by International Classification of Diseases , 9th revision , codes from the computerized discharge abstract s of the two GHC hospitals , bills for out-of-plan services provided by non-GHC physicians and health care facilities , and Washington State death records . A trained records abstract or , assisted by study physicians , vali date d the incident infa rct ions by review ing available inpatient medical records . Previous work ( 25 ) has confirmed the accuracy and completeness of the methods used for ascertainment of myocardial infa rct ion .  Persons were excluded if they were younger than 30 or older than 79 years of age at the time of the incident infa rct ion , had previously had a myocardial infa rct ion , had the incident infa rct ion as a result of surgery or another procedure , died before hospital discharge , or had no information available in the medical record after the incident infa rct ion . A total of 50 patients ( 1.8 % of the total otherwise eligible patients ) were discharged alive from the hospital but had no information in the chart after the incident infa rct ion . Persons were also excluded if they had made fewer than four visits to GHC or had been enrolled in GHC for less than 1 year before the incident infa rct ion . Among persons otherwise eligible for inclusion , 9.3 % were excluded because of inadequate duration of enrollment in GHC . Of the 2677 patients who were initially eligible , 58 were excluded because of indeterminate smoking status , leaving 2619 persons ( 97.8 % of the original cohort ) for analysis . The Human Subjects Review Committees of GHC approved the study . Smoking Status We identified smoking status on the basis of ambulatory care and inpatient records . The GHC ambulatory medical record is an important re source because it serves as the primary method of communication among GHC physicians . It includes not only notes from ambulatory care visits but also discharge summaries of hospitalizations , results of laboratory and diagnostic tests , consultant reports , responses to annual GHC health question naires , and up date d problem lists . Data collection included a review of the entire GHC ambulatory medical record for the period before the first infa rct ion , the period of hospitalization associated with the incident infa rct ion , and the period after the infa rct ion up to a predetermined date in 1996 , 1997 , or 1998 . Patients were classified as nonsmokers ( persons with no history of smoking in the medical record ) , former smokers ( persons who had smoked but had quit before the incident myocardial infa rct ion ) , quitters ( persons who were smoking at the time of the incident myocardial infa rct ion and quit after the infa rct ion ) , and active smokers ( persons who were smoking at the time of the incident myocardial infa rct ion and continued to smoke during follow-up ) . Only those persons who quit smoking after their incident infa rct ion and maintained cessation for the duration of follow-up were classified as quitters . Information about the quit date , number of cigarettes smoked per day , and duration of smoking over time was also recorded . Patients were closely monitored after the incident infa rct ion ; 97.6 % had a clinic visit within 3 months after hospital discharge , and the median number of visits ( physician , nurse , or emergency department visits or hospitalizations ) during the first year after the incident infa rct ion was 9 ( 25th , 75th percentiles : 6 , 14 ) . Clinical and Medication Covariates Trained research assistants review ed the ambulatory care and inpatient medical records to collect information about potential risk factors for coronary disease , such as use of health services ; marital status ; alcohol consumption ; body weight ; height ; and medical conditions such as hypertension , diabetes , and congestive heart failure . Congestive heart failure was determined to have occurred on the basis of the notes of the primary care physician and consultants and the results of diagnostic tests . Hypertension was defined as pharmacologically treated hypertension ; diabetes was defined as diabetes pharmacologically treated with oral hypoglycemic agents or insulin . In addition , laboratory values for r and om serum glucose , total cholesterol , and high-density lipoprotein cholesterol were recorded . Medication use was assessed at the time of hospital discharge after the incident infa rct ion by using information from the discharge summary supplemented with information from the first outpatient visit and the GHC computerized pharmacy data base . The status of the clinical and medication covariates was determined at the time of hospital discharge . Laboratory information was taken from the period before the incident infa rct ion . End Point The outcome of interest was recurrent coronary events , defined as nonfatal myocardial infa rct ion or coronary death . Information on these end points was obtained from the GHC ambulatory medical record , available inpatient records , and the results of matches between Washington State death records and GHC enrollment records . In patients with established coronary disease , if the underlying cause of death was heart disease , heart failure , or arrhythmia , the death was classified as a coronary death . Statistical Analysis Follow-up time began at the date of discharge from the hospital after the incident infa rct ion , and it extended to the date of the first recurrent infa rct ion , coronary death , or censoring . Persons were censored at the date of death from causes other than heart disease , the date of unenrollment from GHC , or the end of the assigned follow-up period . Cox proportional-hazards regression analysis with a time-dependent smoking status variable was used to model the association of smoking status and recurrent coronary events after adjustment for potential confounding factors ( 26 ) . A patient who quit smoking during hospitalization for the incident myocardial infa rct ion was classified as a quitter . For those who quit smoking after discharge , smoking status was modeled with person-years accrued initially as if the patient were an active smoker and then after cessation as if the patient were a quitter . To investigate the risk for recurrent coronary events in relation to the duration of smoking cessation , we divided follow-up time into four mutually exclusive categories of duration of cessation ( 0 to < 6 months , 6 to < 18 months , 18 to < 36 months , and 36 months ) . Because the underlying time scale used in the regression analysis was time since hospital discharge after the first myocardial infa rct ion , the Cox model adjusts for time since infa rct ion , enabling an assessment of the relationship of duration of cessation independent of time since infa rct ion . In addition , because most patients who quit smoking did so very soon after the incident infa rct ion , time since hospital discharge and time since cessation of smoking were similar for many quitters . To help discern whether the change seen among quitters in the hazard ratio over time was due to smoking cessation rather than to any other characteristic of smokers that changed over time after discharge , we also evaluated whether the coronary event hazard ratio among active smokers varied with time since infa rct ion . We calculated the unadjusted rates of recurrent
REVIEW ER 'S CONCLUSIONS Quitting smoking is associated with a substantial reduction in risk of all-cause mortality among patients with CHD .
This 36 % risk reduction appears substantial compared with other secondary preventive therapies such as cholesterol lowering which have received greater attention in recent years .
The risk reduction associated with quitting smoking seems consistent regardless of differences between the studies in terms of index cardiac events , age , sex , country , and time period .
BACKGROUND Although the importance of smoking as a risk factor for coronary heart disease is beyond doubt , the speed and magnitude of risk reduction when a smoker with coronary heart disease quits are still subjects of debate .
OBJECTIVES To estimate the magnitude of risk reduction when a patient with CHD stops smoking .