Harald Kipp

Risk of Hemorrhagic Stroke in Asian American Ethnic Groups

The sparseness of prospective data about hemorrhagic stroke (HS) risk among Asian American ethnic groups led to the investigation of 128,934 persons with self-classified ethnicity at health examinations in 1978–1985. Subsequently, 431 persons were hospitalized for HS; 31% for subarachnoid hemorrhage (SAH) and 69% for intracerebral hemorrhage (ICH). Ethnic predictors of HS were studied by Cox proportional hazard models with 7 covariates. With whites as reference, the adjusted relative risk (95% CI) of all Asians for HS was 1.6 (1.1–2.3, p = 0.01), due substantially to increased risks of SAH in Japanese people and ICH in Filipinos. These data mandate emphasis upon preventive measures in these groups.

The Confounded Relation of Coffee Drinking to Coronary Artery Disease

After decades of conflicting studies, the relation of coffee drinking to coronary artery disease (CAD) risk remains unresolved. Using Cox proportional-hazards models with 5 covariates, 127,212 subjects who supplied baseline data at voluntary health examinations from 1978 to 1985 were studied. Subsequently, 8,357 subjects were hospitalized for CAD. Coffee drinking was unrelated to CAD risk in 58,888 never smokers, but in ex-smokers and current baseline smokers, daily coffee intake was associated with higher CAD risk. This disparity was generally consistent in stratified subgroups. In conclusion, this relation of coffee consumption to increased CAD risk only in smokers could be explained by incomplete control for smoking, by other traits of smokers, or by an adverse biologic interaction of a coffee ingredient with smoking effect on CAD.

Vasectomy and the Incidence of Hospitalized Illness

To determine the long-term effects of vasectomy on health we studied the incidence of hospitalized illness in 4,385 vasectomized and 13,155 age and race-matched nonvasectomized men. In none of the 16 disease groupings we examined was the incidence of hospitalized illness in the vasectomized men significantly different from that in the nonvasectomized men, considering men with all durations of vasectomy. Neither the incidence of acute myocardial infarction, other ischemic heart disease nor that of all atherosclerotic diseases considered as a group was significantly different between the vasectomized and nonvasectomized men, even in those whose duration of vasectomy was 10 years or more. These data are reassuring, providing no evidence for an adverse health effect of vasectomy in men.

Physiologic measures in men with and without vasectomies

Blood pressure, hematologic and blood chemistry measurements, and serologic tests for syphilis were performed on 4385 vasectomized and 13,155 age- and race-matched, nonvasectomized men who had multiphasic health checkups as members of a large prepaid medical care program in California. The study was carried out from 1977 through 1980. Age distributions of the vasectomized and nonvasectomized men were identical, 33% of both groups being 40 years old or younger, 33% being 41-50, and 34% being 51 or older. 37% of the vasectomized men had their vasectomies 10 or more years before their examination. Systolic blood pressure was slightly but significantly lower and potassium was slightly but significantly higher in the vasectomized group. All other differences were small and not biologically important. These data agree with other studies of vasectomized humans, in which no association of vasectomy with adverse health outcomes, including atherosclerosis, has been found.