The risk of myocardial infarction 10 or more years after vasectomy in men under 55 years of age

Abstract

To evaluate whether vasectomy is associated with a subsequent increase in the incidence of myocardial infarction 10 or more years after surgery and whether an effect is more pronounced in those already predisposed to a myocardial infarction, a hospital-based case-control study was carried out in men aged less than 55 years. The men were interviewed during 1980-1983 in 78 hospitals in Massachusetts, Rhode Island, Connecticut, and New York. Among 2,238 men with first episodes of myocardial infarction, 332 (15%) had undergone vasectomy, compared with 572 (16%) of 3,361 controls. Vasectomy greater than or equal to 10 years earlier was reported by 150 cases and 180 controls, to yield a multivariate relative risk estimate of 1.0 after allowance for potential confounding factors (95% confidence interval (Cl) = 0.8-1.3); for vasectomy greater than or equal to 15 years before, based on 34 cases and 33 controls, the estimate was 1.1 (95% Cl = 0.7-2.0). In men predisposed to myocardial infarction because of more advanced age, cigarette smoking, elevated cholesterol level, hypertension, angina pectoris, or other risk factors, vasectomy did not appear to increase the risk further, even after intervals of greater than or equal to 10 years. The results provide evidence against an increased risk of myocardial infarction greater than or equal to 10 years after vasectomy overall and in those known to be predisposed because of other risk factors.

PIP: A hospital-based case-control study was conducted in men under age 55 to evaluate whether vasectomy is associated with a subsequent increase in the incidence of myocardial infarction 10 or more years after surgery and whether an effect is more pronounced in those already predisposed to a myocardial infarction. The men were interviewed during 1980-83 in 78 hospitals in Massachusetts, Rhode Island, Connecticut, and New York. A standard questionnaire was used to obtain information on history of vasectomy, personal characteristics, medical history, cigarette smoking, coffee and tea consumption, history of drug use, and other factors. In addition, the Framingham Type A Personality Scale questionnaire was administered, in which a higher score indicates a greater tendency to Type A behavior, and the men were asked about leisure time physical activities during the year before admission. After discharge, the diagnosis that led to admission was abstracted from the medical record. The participation rate was 87% among the potential cases and 93% among the potential controls. All cases were interviewed men 20-54 years of age admitted for a 1st episode of myocardial infarction, the diagnosis of which met WHO criteria. Men for whom it was judged that the myocardial infarction could have been caused by preexisting heart disease were excluded. There were 2238 cases: median age, 46 years; 97% white. All controls were interviewed men from the pool of potential controls who were 20-54 years old, had no history of myocardial infarction, and were admitted for diagnoses judged to be unrelated to vasectomy. There were 3361 controls: median age, 42 years; 96% white. Among the 2238 cases, 332 (15%) reported having had a vasectomy, compared with 572 (16%) of 3361 controls. Vasectomy more than 10 years previous was reported by 150 cases and 180 controls to yield a multivariate relative risk estimate of 1.0 after allowance for potential confounding factors; for vasectomy more than 15 years previous, based on 34 cases and 33 controls, the estimate was 1.1. In men predisposed to myocardial infarction because of more advanced age, cigarette smoking, elevated cholesterol level, hyperstension, angina pectoris, or other risk factors, vasectomy did not appear to increase the risk further, even after intervals of more than 10 years. The results offer evidence against an increased risk of myocardial infarction more than 10 years after vasectomy overall and in those known to be predisposed because of other risk factors.