Risk of Ischemic Heart Disease in Self-reported Snorers* A Prospective Study of 2, 937 Men Aged 54 to 7 4 Years: The Copenhagen Male Study Paul ]ennum , MD; Hans Ole Hein, MD; Paul Suadicani, DD; and Finn Gyntelberg, MD, Dr Med Sc Former studies have demonstrated an association be- tween habitual snoring and cardiovascular morbidity and mortality. Control for the influence of potential confounders has been inadequate. To further elucidate the issue, we examined the association between snoring and future risk of ischemic heart disease (IHD) while controlling for a number of major cardiovascular risk factors and potential effect modifiers. Some 2,937 men without overt cardiovascular disease, aged 54 to 74 y (mean=63 years), were classified according to snoring habits and followed up prospectively during 6 years (1985 to 1991). Potential cardiovascular disease risk factors included in the study were as follows: smoking, alcohol consumption, physical activity, hypertension, blood pressure, body mass index (BMI) (kgXm - 2 ), social class, and serum concentrations of selenium, cotinine, total cholesterol, high-density lipoprotein cholesterol, and triglycerides. During the 6-year follow-up period, 182 men (6.2%) had an IHD event (42 were fatal), and 274 men died from all causes (9.3%). There was no dif- ference in the prevalence of snorers among those who had an IHD event and those who did not during the follow-up period, 49.9% vs 50.5%, respectively. Among A number of studies have demonstrated an associ- ation between habitual snoring and cardiovas- cular disease (CVD). 1 - 6 In most studies, control for the influence of potential confounders has been inadequate. For this reason, a causal relationship has been questioned. 7 • 8 Major CVD risk factors like tobacco smoking, alcohol consumption, and body mass index (BMI) are associated with snoring. 9 - 16 Accordingly, the necessity to control for the influence of these factors is obvious. The purpose of this study was to elucidate the as- sociation between snoring and the future risk of ischemic heart disease (IHD) after adjustment for a substantial number of cardiovascular risk factors. *From the Glostrup Population Studies, Department of Internal Medicine C, Glostrup Hospital (Drs. Jennum and Rein), and The Epidemiological Research Unit, Department of Occupational Medicine, Rigshospitalet (Drs. Rein, Suadicani, and Gyntel- berg), Copenhagen, Denmark. Manuscript received April25, 1994; revision accepted November 29. Reprint requests: Dr. ]ennum, Dept of Clinical Neurorhysiology 145, Hvidovre Hospital DK-2650 Hvidovre, Denmark 138 the younger half of the cohort (54 to 63 years), the age- adjusted incidence of IHD was slightly but not signifi- cantly increased in snorers, relative risk (RR)= 1.2 (0.8 to 1.9). When adjustments were made for relevant con- founders-use of tobacco, alcohol consumption, and BMI -the RR dropped to 1.0 (0.6 to 1.6). Among the older half (64 to 74 years), there was no increased risk in snorers, RR=l.O (0.7 to 1.6). We conclude that there was a slightly increased risk that did not reach statistical significance of IHD in snorers. After multivariate ad- justment, snoring was not associated with risk of IHD in middle-aged and elderly men. (CHEST 1995; 108:138-42) ACM=all causes of mortality; AMI=acute myocardial in- farction; BMI=body mass index; BP=blood pressure; CVD=cardiovascular disease; HDL=high-density lipopro- tein; IHD=ischemic heart disease; RR=relative risk Key words: ischemic heart disease; morbidity; mortality; risk factors; snorers; snoring METHODS The data used are derived from the Copenhagen Male Study. The study was initiated in 1970 as a prospective cardiovascular cohort study. Included were 5,249 men employed at 14 Copen- hagen public and private companies. Their mean age was 48 years (range, 40 to 59 years)17-19 About 15 years later, in 1985/ 1986, a new baseline, used for the present study, was established. All survivors (except 34 emigrants) were traced by means of the Danish Central Person Register and invited to take part in a clinical follow-up study: 3,387 men cor- responding to 75% agreed to participate and gave informed con- sent. Their mean age was 63 years (range, 54 to 74 years). The 1985/ 1986 study took place at the Division of Prospective Medicine, Glostrup University Hospital. The examination con- sisted of the following: (1) an interview by a physician (H.O.H.) based on a previously completed questionnaire; (2) a clinical ex- amination by a physician, including measurements of height, weight, and blood pressure; and (3) a venous blood sample drawn for the determination of serum lipids and serum cotinine, following a fasting period of minimum 12 hs. Risk Factor Assessment From the Questionnaire Snoring Habits: The question was phrased: "Do you know or have you been told that you snore during the night?" Answer Clinical Investigations