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Biomedical subjects

C M Hawkins

Publications and source records attributed to C M Hawkins.

At least 37 records · Page 2Linked to original sources
PubMed1988

The relation between degree of blood pressure reduction and mortality among hypertensives in the Hypertension Detection and Follow-Up Program.

The relation between degree of diastolic blood pressure reduction and mortality was examined among hypertensive persons in the Hypertension Detection and Follow-up Program. This program, conducted from 1973-1979, was a multicenter community-based trial, which followed 10,940 hypertensive participants for five years. The one-year annual visit was the first occasion on which change in blood pressure could be measured on all participants. During the subsequent four years of follow-up on 10,053 participants, 568 deaths occurred. With time-dependent life tables and time-dependent Cox life table regression analyses, the existence of a quadratic function which modeled the relation between diastolic blood pressure reduction and mortality was supported, even after adjusting for other risk factors. The minimum mortality hazard ratio, based on a particular model, occurred at a diastolic blood pressure reduction of 26.2 mmHg (standard error = 13.4) in the whole population and 10.0 mmHg (standard error = 5.3) in the baseline diastolic blood pressure stratum 90-104 mmHg. After this reduction, there was a small increase in the risk of death. There was no evidence of the quadratic function after fitting the same model with systolic blood pressure. Methodological issues involved in studying a particular degree of blood pressure reduction were considered. The confidence interval around the change corresponding to the minimum hazard ratio was wide, and the obtained blood pressure level should not be interpreted as a goal for treatment. Blood pressure reduction was attributed not only to pharmacologic therapy but also to regression to the mean, and to other factors unrelated to treatment.

Actuarial Analysis↗
PubMed1987

Standardized physician preparation of death certificates.

One method for determining cause of death in a clinical trial is to use standard nosological coding of death certificates. In order to look at an alternative approach, the Hypertension Detection and Follow-up Program (HDFP) assessed underlying causes of death through the use of three physicians. These physicians were trained and standardized in the proper recording of cause of death on death certificates. Each physician completed a death certificate for each of the 768 deaths in the HDFP, utilizing all available information, including HDFP records, plus any additional hospital and autopsy records. The new standardized death certificates were then transmitted to a panel of three nosologists who coded the cause of death. The physician preparation procedure was compared with a procedure wherein a panel of three nosologists coded the original death certificate for the underlying cause of death. The procedures agreed on the three-digit International Classification of Disease, Adapted code in 60.1% of the cases. The agreement rate improved to 72.5% when disease codes were collapsed into broad disease categories utilized in the HDFP.

Adult↗
PubMed1985

Dietary therapy slows the return of hypertension after stopping prolonged medication.

This study asks whether prolonged antihypertensive therapy will "cure" a substantial percent of rigorously treated hypertensive patients and whether nutritional change will add an antihypertensive effect and reduce the relapse rate. Of 584 eligible patients normotensive while receiving therapy, 496 were randomized into control and discontinued-medication groups with and without dietary intervention. At 56 weeks, 50% of those who were no longer receiving medication remained normotensive by study criteria. Randomization either to weight-loss group (mean loss of 4.5 kg [10 lb]) or to sodium-restriction group (mean reduction of 40 mEq/day) increased the likelihood of remaining without drug therapy, with an adjusted odds ratio of 2.17 for the sodium group and 3.43 for the weight group. Highest success rates were in the nonoverweight mild hypertensives with sodium restriction (78%) and the overweight mild hypertensives who were reducing their weight (72%). These data demonstrate that weight loss or sodium restriction, in hypertensives controlled for five years, more than doubles success in withdrawal of drug therapy.

Clinical Trials as Topic↗
PubMed1985

A computer program for an illness-death process with time-dependent covariates.

This paper presents a computer program for estimating transition probabilities between states in a stochastic model for an illness-death process which incorporates time-dependent covariates. Parameters are estimated by the method of maximum likelihood using the Newton-Raphson iterative procedure. The program provides the standard normal deviate statistics as well as the value of the maximum of the likelihood function which can be used on repeated applications to test hypotheses concerning coefficients associated with covariates. Although this program is demonstrated by using a model with two 'illness' states and two 'death' states, it is also suitable for analyzing data with models involving fewer states, such as the analysis of survival time with covariates assuming a proportional hazard model.

Computers↗
PubMed1985

Ascertainment of vital status through the National Death Index and the Social Security Administration.

Ascertainment of the vital status of individuals is of central importance to epidemiologic studies which monitor mortality as an end point. Utilizing identifying information collected in 1973-1974, the Hypertension Detection and Follow-up Program, a prospective, multicenter study, followed 25,362 individuals to determine eight-year mortality. In the most recent follow-up, there were 617 individuals whose vital status was not known. Available identifying information on these and on all 1,322 participants known to have died in 1979-1981 was submitted to the National Death Index (NDI) for possible confirmation of vital status. A subset of individuals who had Social Security numbers (490 lost to follow-up and 1,154 known deaths) was also submitted to the Social Security Administration (SSA). The NDI correctly identified 87.0% of the known deaths. Of the 1,154 known deaths (those with known Social Security numbers) submitted to both agencies, the NDI identified 93.1% and the SSA 83.6%. Significant variations by race and sex were noted in the identification rates, in part because of Social Security number discrepancies. False matches through the NDI matching process occurred for 10.4% of the known deaths. In the more restrictive SSA search, only 0.5% false matches resulted. For those lost to follow-up, vital status was ascertained in 57.1%. This paper describes the relative efficacy and attributes of the use of these systems to ascertain vital status.

Aged↗
PubMed1984

Effect of propranolol in postinfarction patients with mechanical or electrical complications.

In "post hoc" subgroup analyses, a simple classification system for patients, based on the presence or absence of findings indicative of electrical and/or mechanical complications early during short-term hospitalization, was applied to the data from the Beta-Blocker Heart Attack Trial (BHAT). In the largest subgroup of BHAT patients who had no reported complications, the 25 month mortality was low and the observed benefit of propranolol therapy small. Patients with electrical complications only had intermediate mortality and a pronounced effect of treatment was observed. Those with mechanical complications had the highest mortality and experienced an intermediate relative benefit of beta-blocker treatment. They also reported the most adverse effects. Post hoc analyses should always be interpreted cautiously. It is important to determine whether these findings are present in other completed beta-blocker trials. On the basis of these analyses alone it is suggested that the present practice of prescribing beta-blockers in postinfarction patients should not be altered.

Arrhythmias, Cardiac↗
PubMed1984

Return of hypertension after withdrawal of prolonged antihypertensive therapy, effect of weight loss, sodium reduction, and baseline factors.

The effect of dietary modification on continued blood pressure control after discontinuation of antihypertensive therapy has been studied. Participants who had been treated for 5 years in the Hypertension Detection and Follow-up Program were enrolled and randomly assigned to continue medication, discontinue medication with no dietary intervention, discontinue medication and reduce weight, discontinue medication and reduce sodium groups. Relapse of hypertension was slow, even without dietary modification. Both weight loss and sodium restriction slowed relapse. The severity of the hypertension and the number of drugs required for hypertension control had a marked effect on the rate of relapse. Relapse was slowest in the participants who had attained the lowest blood pressure on therapy.

Adult↗
PubMed1984

Effect of dietary change on the return of hypertension after withdrawal of prolonged antihypertensive therapy (DISH). Dietary Intervention Study of Hypertension.

The possibility exists that dietary modification may increase the number of patients who remain normotensive after drug withdrawal. In an effort to resolve this question, former Hypertension Detection and Follow-up Program Stepped Care participants (n = 496) were randomized into four major groups at the end of the programme (greater than 5 years antihypertensive therapy): controls (continue medication); discontinue medication, no dietary intervention; discontinue medication and weight loss; discontinue medication and reduce sodium. Groups 1, 2 and 4 were further divided into obese (greater than or equal to 120% ideal weight, and non-obese groups). The weight reduction group (greater than or equal to 120% ideal weight) lost 10.1 +/- 11 lbs without changing dietary sodium (n = 87). The sodium restriction group reduced urine sodium excretion from 145 to 97 mEq per day (n = 169). Sixty per cent of the weight loss group were normotensive at 56 weeks compared to 35% withdrawn from medication without dietary intervention. The highest 56 weeks success rates were in the mild non-overweight hypertensives on sodium restriction (78%), and the mild overweight hypertensives on weight reduction (72%). Randomization to either weight loss group or sodium restriction group increased the likelihood of remaining off drugs (adjusted odds ratio of 3.43 for the weight group and 2.17 for the sodium group (P less than 0.05). Age, severe hypertension greater than 5 years previous to entry into Dietary Intervention Study of Hypertension (DISH) or need for several drugs increased the chance of failure.

Adult↗
PubMed1983

Serum cholesterol and cancer in the Hypertension Detection and Follow-up Program.

The relation between serum cholesterol and cancer incidence was investigated in the population of the Hypertension Detection and Follow-up Program. During the 5 years of follow-up, 286 new cancer cases were documented among the 10,940 participants. Overall, age-adjusted cancer incidence rates, computed by baseline serum cholesterol quartiles, showed a small, but statistically significant, inverse relation between serum cholesterol and cancer incidence. No evidence suggested that the observed relationship was primarily due to confounding by other cancer risk factors, association of low serum cholesterol with incipient but undiagnosed cancer, or problems of competing risks. However, the relationship is weak and a causal interpretation of these immediate results cannot be argued persuasively. Examinations of specific cancer sites and factors related to serum cholesterol are suggested as important lines of research toward clarification of the complex relationships observed.

Adult↗
PubMed1983

A coordinating center in a clinical trial: the Hypertension Detection and Followup Program.

Multicenter clinical trials are often larger and more complex than other methods of clinical inquiry. They tend to involve a number of research or clinical centers and several formal committees. In many of these trials a coordinating center is one of the participating organizational units. This article describes one such coordinating center, that of the Hypertension Detection and Follow-up Program (HDFP). In 1971 the HDFP Coordinating Center was established to assist in planning and implementing this National Heart, Lung, and Blood Institute (NHLBI)-sponsored, multicenter, community-based, randomized, controlled clinical trial. The HDFP Coordinating Center is a large, intricate organization comprised of personnel who perform a wide variety of functions. From 1972 to 1979 it supervised the adherence to a common protocol among the cooperating centers and reported the Program's progress to the various monitoring and review committees, the Steering Committee, and the NHLBI Program Office. The Program screened approximately 159,000 persons ages 30 to 69 years, identifying and following 10,940 hypertensive participants. It has been the responsibility of this Coordinating Center to institute, coordinate, and monitor the data-gathering activities of the study as a whole and to process, store, and analyze the large, multifaceted set of data that were collected.

Clinical Trials as Topic↗
PubMed1983

The impact of selected indices of antihypertensive treatment on all-cause mortality.

Two important questions regarding the results of the Hypertension Detection and Follow-up Program are: 1) how much of the difference in mortality between stepped care and referred care can be attributed to treatment for hypertension, and 2) was there a relationship between treatment of hypertension in the program and the risk of subsequent mortality of the participants? Neither of these questions can be answered within the original randomization scheme of the Hypertension Detection and Follow-up Program; however, statistical techniques can address these two questions. Crude analyses of blood pressures of survivors and deaths in each year of follow-up indicate that survivors had lower blood pressure than persons dying during the interval. An analysis using life table regression with time-dependent covariates suggests that well over half of the excess risk in the referred care group can be attributed to differences in factors related to hypertension treatment. Simultaneously testing the coefficients of the time-dependent variables (diastolic and systolic pressures, blood pressure goal, and medication status) suggests a highly significant relationship between these variables and the risk of subsequent mortality.

Adult↗
PubMed1983

Nosological coding of cause of death.

Death certificates representing 766 decedents who had participated in the Hypertension Detection and Follow-up Program (1973-1979) at one of 14 US centers were given to three nosologists for purposes of coding underlying cause of death. Analyses examined interobserver variability among the three nosologists as well as intraobserver variability for each of the three nosologists. All three nosologists agreed on a three-digit International Classification of Diseases, Adapted (ICDA) code in 90.2% of the cases and at least two out of three agreed in 99.7% of the death certificates examined. Agreement rates improved when disease codes were collapsed into broader categories utilized in the Hypertension Detection and Follow-up Program. When particular disease classifications (e.g., cerebrovascular, ischemic heart disease, myocardial infarction, and neoplasms) were examined, three out of three agreement rates were highest for neoplasms (97.8%) and lowest for myocardial infarction (86.5%). Similarly, two out of three agreement was highest for neoplasms (98.5%) and lowest for myocardial infarction (88.0%). Intranosologist agreement rates were based on a recoded 20% sample of death certificates. Agreement rates for three-digit ICDA codes ranged from 94.8% to 96.1% for the three nosologists. The agreement rates for the general disease categories ranged from 96.7% to 97.4%.

Cardiovascular Diseases↗
PubMed1983

Transmission dynamics of enteric bacteria in day-care centers.

The role of fomites in the transmission of diarrhea in day-care centers was evaluated. During a nine-month period (December 1980-August 1981), inanimate objects and hands of children and staff in five Houston day-care centers were cultured monthly and again during outbreaks of diarrhea. Air was sampled from the classrooms and bathrooms using a single-stage sieve sampler. When a diarrhea outbreak occurred, stool specimens were collected from ill and well children and from staff in the affected rooms. Multiple pathogens accounted for 3 of 11 outbreaks. The rates of isolation of fecal coliforms from hands and classroom objects on routine sampling were 17% (22/131) and 13% (8/64), respectively. During outbreaks of diarrhea, fecal coliforms were recovered with significantly greater frequency from hands (32%; p less than 0.005) and from classroom objects (36%; p less than 0.005). There was no difference in the level of fecal contamination in the toilet areas during outbreak and nonoutbreak periods. Shigella was not isolated in the study; salmonella was isolated on one occasion from a table during an outbreak of salmonellosis. Contamination of hands, communal toys and other classroom objects appeared to play a role in the transmission of enteropathogens in day-care center diarrhea outbreaks and helped to explain the presence of multiple pathogens among those affected.

Air Microbiology↗
PubMed1983

Effect of propranolol in reducing mortality in older myocardial infarction patients. The Beta-Blocker Heart Attack Trial experience.

The results from the Beta-Blocker Heart Attack Trial for patients ages 60-69 years indicate a significant beneficial effect of propranolol and an overall reduction in mortality of 33%. This beneficial effect appears to begin early and continues through 3 years of follow-up. Examination of patient complaints and medical reasons for withdrawing study medication indicates that side effects resulting from propranolol use were infrequent in both the younger and older age groups, and there were no major differences between the two groups. Given these results, and considering the large number of hospital-diagnosed myocardial infarctions that occur each year in persons older than 60 years of age, it appears that the use of propranolol, where not contraindicated, could delay mortality in a substantial number of older postinfarction patients.

Adult↗
PubMed1983

Effects of propranolol on blood lipids and lipoproteins in myocardial infarction.

The effects of propranolol on lipids and lipoproteins were investigated in survivors of a recent myocardial infarction who were enrolled in the double-blind Beta-Blocker Heart Attack Trial. Nonfasting serum samples were obtained in more than 2800 patients assigned randomly to either propranolol or placebo. The propranolol-treated group had high-density lipoprotein cholesterol levels 3-4 mg/dl less and triglyceride concentrations 30-40 mg/dl higher than the placebo group. These effects occurred in men and women in all age categories.

Adult↗
PubMed1980

Two-compartment Markov regression analysis.

This paper presents a computer program for estimating transition rates between states in a two-compartment Markov process, where the rates are functions of covariates. Parameters are estimated by the method of maximum likelihood using the Newton-Raphson iterative procedure. The program provides statistics for testing hypotheses concerning regression coefficients and calculates observed versus expected values in order to assess the fit of the model to the data.

Age Factors↗