A north-south comparison of blood pressure and factors related to blood pressure in the People's Republic of China: a report from the PRC-USA Collaborative Study of Cardiovascular Epidemiology.

OBJECTIVES: To compare blood pressures in northern (Beijing) and southern (Guangzhou) Chinese population samples aged 35-54 years, males and females, urban and rural, and to assess the role of blood pressure-related traits in explaining north-south differences. DESIGN: Cross-sectional surveys were conducted in 1983-1984 of northern and southern populations employed in industry (urban) or farming (rural). METHODS: In the north samples were selected from the Capital Iron and Steel Complex (urban) and Shijingshan district (rural); in the south samples from the Guangzhou Shipyard (urban) and Panyu County (rural) were used. RESULTS: The number of subjects surveyed in north and south were 4706 and 4179, respectively: 1500 and 1052 urban males, and 717 and 914 rural males; and 1300 and 1061 urban females, and 1189 and 1152 rural females, respectively. Average systolic (SBP) and diastolic (DBP) blood pressures, were consistently higher in the north than in the south. SBP and DBP were significantly and independently related to age, body mass index, heart rate, use of antihypertensive drugs, serum triglycerides level, alcohol use (males only) and inversely to cigarette smoking. Northerners were older, taller, heavier and had higher body mass index and triglycerides level than southerners. With adjustment of SBP and DBP for blood pressure-related traits, north-south blood pressure differences decreased, but remained significant for urban males, rural males and rural females, with sizeable differences for rural samples in particular. CONCLUSIONS: North-south differences in blood pressure in these samples are accounted for only partly by north-south differences in the cited blood pressure-related traits. The role of other traits requires assessment.

A double blind study of the effects of zinc sulfate on taste and smell dysfunction.

A randomized, double blind crossover study of the effects of zinc sulfate and placebo was carried out in 106 patients with taste and smell dysfunction secondary to a variety of etiological factors. In the patient group prior to treatment, mean serum zinc concentration and leukocyte alkaline phosphatase activity were significantly lower than normal. Results indicate that zinc sulfate was effectively equivalent to placebo in the treatment of these disorders. Although these results demonstrate abnormalities of zinc metabolism in some patients with taste and smell dysfunction they fail to provide evidence for a single, therapeutic approach to the many disorders which are associated with abnormalities of taste and smell. However, the methods and procedures developed in this study demonstrate that taste and smell dysfunction can be studied in a quantitative, systematic manner.

Decline of coronary heart disease mortality in the United States.

Annual mortality rates for cardiovascular disease in the U.S. have declined steadily since at least 1968, with an accelerated rate of decline since approximately 1972. Although these trends have been seen in both men and women and in both Blacks and Whites, there have been relative differences in the rate of decline by region and state within the U.S. The relative importance of improved prevention vs. treatment in accounting for this decline has been discussed at length but not resolved, and efforts to gather relevant data are still being undertaken. Nonetheless, important changes have occurred in dietary habits with, for example, lower animal and higher vegetable fat consumption; in cigarette smoking rates, with especially important declines in middle-aged men; and in high blood pressure control, with improved levels in both genders and especially in Blacks, who have the highest rates.

Planning and implementation of large clinical trials.

The large-scale collaborative clinical trial has become an important activity in the biomedical research spectrum. It is the clinical trial that determines most precisely the efficacy of treatment of preventive regimens. These large studies, which usually cost tens of millions of dollars and use large numbers of research facilities, have a major impact on research and medical practice. Consequently, it is required that a number of factors be carefully assessed before any such study is undertaken. A formalized decision process has been developed by the National Heart, Lung and Blood Institute to aid in the formulation, design, conduct, analysis and dissemination of the results of clinical trials. This decision process, which provides a planning framework for the trial, is described here. The framework is constructed around three major decision points at which resources are committed: to plan the trial, to conduct the trial, and to terminate and disseminate the results of the trial.

Overview of recent clinical and methodological advances from clinical trials of cardiovascular disease.

Concurrently controlled, randomized clinical trials play an important role in the validation of treatment and control measures of cardiovascular disease. As such trials have been carried to conclusion, a great deal has been learned not only about the treatment of the disease but also about the methodology of clinical trials. Seven recently completed clinical trials, the Coronary Drug Project, the Aspirin Myocardial Infarction Study, the Anturane Reinfarction Trial, the Hypertension Detection and Follow-Up Program and three drug trials of betablockers, are reviewed from the perspective of both their clinical and methodological significance.

Effect of elevated triglycerides on the diffusing capacity of man.

In view of the decreased diffusing capacity recently reported in man during lipid infusion, studies have now been made on the effects of hyperlipidemia on the diffusing capacity for carbon monoxide (DLco). In normal volunteers and patients with hyperlipidemias, DLco and plasma triglyceride concentrations were determined during fat tolerance tests and while the patients were on diets that increased or decreased triglyceride concentrations. During the fat tolerance tests, the largest triglyceride and DLco changes were from 346 mg per 100 ml with a DLco of 18.8 ml per min per mm Hg to 1,545 mg per 100 ml with a DLco of 23.4 ml per min per mm Hg. While patients were on speical diets, the largest triglyceride and DLco changes were from 5,102 mg per 100 ml and 29.0 ml per min per mm Hg to 492 mg per 100 ml and 26.4 ml per min per mm Hg, respectively. Sta tistical tests showed no significant change of DLco with change in triglyceride concentration. The data suggest that there is normally no association between change in triglyceride concentration and change in DLco, and that triglycerides normally transported in plasma, even when present in extreme amounts as chylomicrons or very-low-density lipoprotein, do not affect the DLco.

Treatment of hypertension with biofeedback and relaxation techniques.

The present study describes a 16-week trial of the use of a combination of biofeedback and relaxation techniques for the treatment of hypertension. Twenty-two hypertensive patients were randomly allocated to one of three groups: (1) diastolic blood pressure feedback, electromyographic feedback, and verbal relaxation; (2) sham blood pressure feedback; and (3) no treatment. For the 14 patients completing active treatment during an initial or crossover period, the average changes in blood pressure as measured outside the laboratory were minimal (0/-1 and +1/0 mm Hg, supine and standing, respectively). Average blood pressure reduction in the laboratory was no greater with active than with sham blood pressure feedback (-3/-2 vs. -5/-2 mm Hg). One subject, however, after showing no change in blood pressure during sham feedback, achieved pronounced and prolonged improvement following active treatment. Overall results do not support the usefulness of these techniques as primary therapy in most hypertensives.

Randomized clinical trials. Perspectives on some recent ideas.

In spite of the controversy over the role of randomized clinical trials in medical research, the rationale underlying such trials remains persuasive as compared to recent suggestions for alternative non-randomized studies such as those relying on the use of historical controls and adjustment technics. Others have suggested that recent statistical innovations for improving clinical trials, including adaptive allocation of treatment to patients and sequential stopping procedures, are underutilized. These innovations, though theoretically interesting, are not easily adapted to large-scale, complex medical trials in which there may be multiple end points and delayed response times. Ethical considerations suggest that randomized trials are more suitable than uncontrolled experimentation in protecting the interests of patients. Randomized clinical trials remain the most reliable method for evaluating the efficacy of therapies.

Clinical trials of hepatitis B immune globulin. Development of policies and materials for the 1972-1975 studies sponsored by the National Heart and Lung Institute.

Plasma from persons with high titers of hepatitis B antibody (anti-HBs) was used to manufacture one lot of hepatitis B "immune" globulin sufficient for four interlocking clinical trials of prevention or modification of hepatitis B infections. The trials were carried out in renal dialysis units, in medical personnel with accidental exposures to hepatitis B, in transfused patients, and in patients with fulminant hepatitis. A single policy board developed protocols that allowed comparisons among the four studies while respecting the unique requirements of each.

Primary care outcomes in patients treated by nurse practitioners or physicians: a randomized trial.

CONTEXT: Studies have suggested that the quality of primary care delivered by nurse practitioners is equal to that of physicians. However, these studies did not measure nurse practitioner practices that had the same degree of independence as the comparison physician practices, nor did previous studies provide direct comparison of outcomes for patients with nurse practitioner or physician providers. OBJECTIVE: To compare outcomes for patients randomly assigned to nurse practitioners or physicians for primary care follow-up and ongoing care after an emergency department or urgent care visit. DESIGN: Randomized trial conducted between August 1995 and October 1997, with patient interviews at 6 months after initial appointment and health services utilization data recorded at 6 months and 1 year after initial appointment. SETTING: Four community-based primary care clinics (17 physicians) and 1 primary care clinic (7 nurse practitioners) at an urban academic medical center. PATIENTS: Of 3397 adults originally screened, 1316 patients (mean age, 45.9 years; 76.8% female; 90.3% Hispanic) who had no regular source of care and kept their initial primary care appointment were enrolled and randomized with either a nurse practitioner (n = 806) or physician (n = 510). MAIN OUTCOME MEASURES: Patient satisfaction after initial appointment (based on 15-item questionnaire); health status (Medical Outcomes Study Short-Form 36), satisfaction, and physiologic test results 6 months later; and service utilization (obtained from computer records) for 1 year after initial appointment, compared by type of provider. RESULTS: No significant differences were found in patients' health status (nurse practitioners vs physicians) at 6 months (P = .92). Physiologic test results for patients with diabetes (P = .82) or asthma (P = .77) were not different. For patients with hypertension, the diastolic value was statistically significantly lower for nurse practitioner patients (82 vs 85 mm Hg; P = .04). No significant differences were found in health services utilization after either 6 months or 1 year. There were no differences in satisfaction ratings following the initial appointment (P = .88 for overall satisfaction). Satisfaction ratings at 6 months differed for 1 of 4 dimensions measured (provider attributes), with physicians rated higher (4.2 vs 4.1 on a scale where 5 = excellent; P = .05). CONCLUSIONS: In an ambulatory care situation in which patients were randomly assigned to either nurse practitioners or physicians, and where nurse practitioners had the same authority, responsibilities, productivity and administrative requirements, and patient population as primary care physicians, patients' outcomes were comparable.