Rerouting of Cerebral Circulation

We describe an adolescent with long-standing atresia of the head/neck arteries and severe aortic coarctation. Because of progressive symptoms, a series of interventions was undertaken to provide direct aorta–to–carotid artery flow and coarctation treatment. This case highlights the unusual physiological features associated with atresia of all head and neck arteries. (Level of Difficulty: Advanced.)

Prepopulated radiology report templates: a prospective analysis of error rate and turnaround time

Current speech recognition software allows exam-specific standard reports to be prepopulated into the dictation field based on the radiology information system procedure code. While it is thought that prepopulating reports can decrease the time required to dictate a study and the overall number of errors in the final report, this hypothesis has not been studied in a clinical setting. A prospective study was performed. During the first week, radiologists dictated all studies using prepopulated standard reports. During the second week, all studies were dictated after prepopulated reports had been disabled. Final radiology reports were evaluated for 11 different types of errors. Each error within a report was classified individually. The median time required to dictate an exam was compared between the 2 weeks. There were 12,387 reports dictated during the study, of which, 1,173 randomly distributed reports were analyzed for errors. There was no difference in the number of errors per report between the 2 weeks; however, radiologists overwhelmingly preferred using a standard report both weeks. Grammatical errors were by far the most common error type, followed by missense errors and errors of omission. There was no significant difference in the median dictation time when comparing studies performed each week. The use of prepopulated reports does not alone affect the error rate or dictation time of radiology reports. While it is a useful feature for radiologists, it must be coupled with other strategies in order to decrease errors.

Effect of pravastatin on coronary disease events in subgroups defined by coronary risk factors: the Prospective Pravastatin Pooling Project

BACKGROUND

Previous trials have had insufficient numbers of coronary events to address definitively the effect of lipid-modifying therapy on coronary heart disease in subgroups of patients with varying baseline characteristics.

METHODS AND RESULTS

The data from 3 large randomized trials with pravastatin 40 mg were pooled and analyzed with the use of a prospectively defined protocol. Included were 19 768 patients, 102 559 person-years of follow-up, 2194 primary end points (coronary death or nonfatal myocardial infarction), and 3717 expanded end points (primary end point, CABG, or PTCA). Pravastatin significantly reduced relative risk in younger (<65 years) and older (>/=65 years) patients, men and women, smokers and nonsmokers, and patients with or without diabetes or hypertension. The relative effect was smaller, but absolute risk reduction was similar in patients with hypertension compared with those without hypertension. Relative risk reduction was significant in predefined categories of baseline lipid concentrations. Tests for interaction were not significant between relative risk reduction and baseline total cholesterol (5% to 95% range 177 to 297 mg/dL, 4.6 to 7.7 mmol/L), HDL cholesterol (27 to 58 mg/dL, 0.7 to 1.5 mmol/L), and triglyceride (74 to 302 mg/dL, 0.8 to 3.4 mmol/L) concentrations, analyzed as continuous variables. However, for LDL cholesterol, the probability values for interaction were 0.068 for the prespecified primary end point and 0.019 for the expanded end point. Relative risk reduction was similar throughout most of the baseline LDL cholesterol range (125 to 212 mg/dL, 3.2 to 5.5 mmol/L) with the possible exception of the lowest quintile of CARE/LIPID (<125 mg/dL) (relative risk reduction 5%, 95% CI 19% to -12%).

CONCLUSIONS

Pravastatin treatment is effective in reducing coronary heart disease events in patients with high or low risk factor status and across a wide range of pretreatment lipid concentrations.

Decision rules for predicting future lipid values in screening for a cholesterol reduction clinical trial

Recent large clinical trials have required screened patients to have serial measurements of an entry criteria variable, eliminating patients form further consideration if the average value is not in the eligibility range specified by the trial protocol. The increasing costs of large clinical trials required that they be executed efficiently. One way to improve efficiency would be to reduce the number of required screening measurements for a patient likely to be ineligible. A procedure is proposed that predicts the value of an average based on n measurements serially obtained on a patient during the screening phase when only m < n measurements are available. The employment of this procedure in a large clinical trial that uses low-density lipoprotein (LDL) cholesterol, total cholesterol, and triglycerides as entry criteria during the screening process is described. As a second example, this procedure is applied to population screening for lipid levels above a treatment threshold. The National Cholesterol Education Program recommends that the average of two LDL cholesterol measurements be used to determine whether LDL cholesterol is above 130 mg/dl, the threshold for treating patients with coronary heart disease. However, data from a sample of patients from a postinfarction population suggest that, if a single LDL cholesterol is above 146 mg/dl, the probability is greater than 95% that the average of the two LDL cholesterol measurements will be above 130 mg/dl.

Rationale and design for the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). ALLHAT Research Group

Are newer types of antihypertensive agents, which are currently more costly to purchase on average, as good or better than diuretics in reducing coronary heart disease incidence and progression? Will lowering LDL cholesterol in moderately hypercholesterolemic older individuals reduce the incidence of cardiovascular disease and total mortality? These important medical practice and public health questions are to be addressed by the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), a randomized, double-blind trial in 40,000 high-risk hypertensive patients. ALLHAT is designed to determine whether the combined incidence of fatal coronary heart disease (CHD) and nonfatal myocardial infarction differs between persons randomized to diuretic (chlorthalidone) treatment and each of three alternative treatments--a calcium antagonist (amlodipine), an angiotensin converting enzyme inhibitor (lisinopril), and an alpha-adrenergic blocker (doxazosin). ALLHAT also contains a randomized, open-label, lipid-lowering trial designed to determine whether lowering LDL cholesterol in 20,000 moderately hypercholesterolemic patients (a subset of the 40,000) with a 3-hydroxymethylglutaryl coenzyme A (HMG CoA) reductase inhibitor, pravastatin, will reduce all-cause mortality compared to a control group receiving "usual care." ALLHAT's main eligibility criteria are: 1) age 55 or older; 2) systolic or diastolic hypertension; and 3) one or more additional risk factors for heart attack (eg, evidence of atherosclerotic disease or type II diabetes). For the lipid-lowering trial, participants must have an LDL cholesterol of 120 to 189 mg/dL (100 to 129 mg/dL for those with known CHD) and a triglyceride level below 350 mg/dL. The mean duration of treatment and follow-up is planned to be 6 years. Further features of the rationale, design, objectives, treatment program, and study organization of ALLHAT are described in this article.

Effect of atenolol and reserpine on selected events in the systolic hypertension in the elderly program (SHEP)

The effect of atenolol and reserpine on incidence of strokes, coronary heart disease (CHD), cardiovascular disease (CVD), and mortality was assessed in 4736 persons aged 60 years and older with isolated systolic hypertension. Participants were randomized to either chlorthalidone (2371), with step-up to atenolol, or reserpine if needed, or placebo (2365). The average baseline SBP/DBP was 170/77 mm Hg. In the active treatment group, step 1, dose 1 was chlorthalidone, 12.5 mg/day; dose 2 was 25 mg/day. For step 2, dose 1 was atenolol 25 mg/day (or reserpine 0.05 mg/day if atenolol was contraindicated); dose 2 was 50 mg/day (reserpine, 0.10 mg/day). During 4.5 years average follow-up, 32% (757) of the active treatment group were on atenolol, with an average exposure of two years and 8% (193) were on reserpine with an average exposure of 1.7 years. Overall there were 96 strokes, 140 CHD events and 289 CVD events among the 2365 active group participants. Using time-dependent lifetable regression with adjustment for several variables, the addition of either atenolol or reserpine to chlorthalidone did not substantially alter the risk ratios for chlorthalidone alone. The relative risk for CHD events for atenolol versus no atenolol was 1.04 (95% confidence interval: 0.58, 1.86) and for reserpine versus no reserpine was 0.93 (95% confidence interval: 0.29, 2.96). The relative risk for atenolol were 0.84 (95% confidence interval: 0.54, 1.30) for death, 1.34 (95% confidence interval: 0.80, 2.28) for stroke, and 1.07 (95% confidence interval: 0.71, 1.61) for CVD. For reserpine, the corresponding relative risks and confidence intervals were 0.65 (0.26, 1.59) for death, 0.27 (0.04, 2.26) for stroke, and 0.55 (0.20, 1.49) for CVD. Thus, the beneficial effects in several outcomes in Systolic Hypertension in the Elderly Program (SHEP) were due to the treatment regimen of lowering blood pressure based on low-dose chlorthalidone (plus atenolol or reserpine as required to meet blood pressure criteria). Additional (independent) benefits attributable to atenolol or to reserpine were not identified. However, a greater number of patients might have been necessary to adequately evaluate potential differential effects of these drugs, especially for reserpine.

Conclusions and implications of the systolic hypertension in the elderly program

Isolated systolic hypertension has a higher prevalence with age and an associated excess cardiovascular risk. The Systolic Hypertension in the Elderly Program (SHEP) was a randomized, prospective, double blind clinical trial to assess the efficacy and safety of a antihypertensive regimen based on low dose diuretic therapy in reducing the five year combined incidence of fatal and nonfatal stroke. SHEP demonstrated a significant 36% reduction in stroke incidence. Also, 27% reduction in coronary heart disease incidence and a 32% reduction in major cardiovascular disease incidence were achieved. The benefits accrued to all subgroups identified based on baseline age, race, sex, blood pressure, serum cholesterol levels, and ECG abnormalities. A low-dose diuretic regimen should be the initial treatment of choice for most hypertensive patients, based on demonstrated reduction in risk for major cardiovascular events, its safety, acceptance by patients, and low cost.

Statistical considerations in monitoring the Systolic Hypertension in the Elderly Program (SHEP)

The Systolic Hypertension in the Elderly Program (SHEP), a randomized, double-masked, placebo-controlled trial of 4736 persons, was designed to assess the efficacy of antihypertensive drug treatment to reduce the risk of fatal and nonfatal strokes among people age 60 and over with isolated systolic hypertension. The statistical method used in interim monitoring of results was conditional power (or stochastic curtailment). The findings did not become conclusive until near the completion of the trial, and therefore SHEP was continued to its scheduled closing date. The trial demonstrated a 36% reduction in the incidence of stroke in the active treatment group (P = .0003). In addition to evaluating overall efficacy of treatment, the monitoring process considered such other issues as nonstroke outcomes, lag time between first report of stroke and final confirmation of stroke diagnosis, consistency of results across subgroups, and completeness of follow-up. The purpose of this article is to review these factors with primary emphasis on the statistical aspects.

Analysis of a clinical trial involving a combined mortality and adherence dependent interval censored endpoint

Clinical trials often involve a variety of clinical and laboratory measures that are used as endpoints and sometimes two of these measures are combined in one endpoint. When the individual components of such a combined endpoint are 'time to event' measurements, the analysis is straightforward if each of the components is measured frequently and regularly over time. However, the analysis of the combined endpoint is more difficult when one component of the endpoint is right censored and the other is interval censored. This paper describes a statistic, based on a rank ordering of events for such a combined measure. The power of the test statistic is explored.

Effect of antihypertensive therapy on weight loss. The Trial of Antihypertensive Interventions and Management Research Group

We report the effect of weight changes of the type of antihypertensive medication prescribed in a trial of the relative efficacy of drug and dietary measures in mild hypertension. The Trial of Antihypertensive Interventions and Management studied 878 mildly hypertensive individuals randomly assigned, in a 3 x 3 design, to no diet change, weight loss, or a low sodium-high potassium diet and to placebo, 25 mg chlorthalidone, or 50 mg atenolol. The type of drug prescribed affected weight change with all diets. The drug effect on weight change, present in all groups at 6 months, was most pronounced in those randomly assigned to the weight loss diet, where the placebo group lost 4.4 kg, the atenolol group lost 3.0 kg, and the chlorthalidone group lost 6.9 kg. The group differences were attenuated but persisted at 24 months. We suggest that the antihypertensive drug prescribed affects the success of a conjoint weight loss program and speculate that the difference between the drugs may be due to their intrinsic effects on the sympathetic nervous system and related metabolic changes.

Rationale and design of a secondary prevention trial of lowering normal plasma cholesterol levels after acute myocardial infarction: the Cholesterol and Recurrent Events trial (CARE)

Recent clinical trials of primary and secondary prevention of cardiovascular disease have demonstrated that lowering plasma cholesterol decreases the incidence of coronary heart disease in patients with elevated plasma cholesterol. However, it is not known whether patients with established coronary artery disease and normal plasma cholesterol can be benefited. Several previous prevention trials reviewed in this report found that patients who had plasma cholesterol levels at baseline in the upper portion of the eligibility range (e.g., greater than 240 mg/dl) received greater benefit from hypolipidemic diet or drug therapy than patients who had lower plasma cholesterol levels at baseline. The recent availability of drugs that are more potent and less prone to cause adverse reactions than previous regimens permits this important question to be addressed. The Cholesterol and Recurrent Events trial is testing whether pravastatin, a hydroxymethylglutaryl coenzyme A reductase inhibitor, will decrease the sum of fatal coronary heart disease and nonfatal myocardial infarction (MI) in patients who have recovered from a MI and who have normal total cholesterol levels. Fatal cardiovascular disease and total mortality are important secondary end points. The trial is enrolling 4,000 men and women from 80 centers throughout North America, age 21 to 75 years, who have survived MI for 3 to 20 months, who have plasma total cholesterol less than 240 mg/dl (6.2 mmol/liter) and low-density cholesterol of 115 to 174 mg/dl (3.0 to 4.5 mmol/liter), and who are representative of the general population of patients with MI. Patients are randomized to either active or inactive drug therapy. Active therapy consists of pravastatin, 40 mg/day, designed to achieve an average decrease in low-density lipoprotein cholesterol of approximately 30%, and an increase in high-density lipoprotein of 5%. The average duration of follow-up will be greater than or equal to 5 years. To protect against a lower than expected rate of recurrent events, the trial will be continued until a predetermined fixed number of coronary heart disease events occurs in the entire cohort so that the original sensitivity of the trial will be maintained.

Effect of antihypertensives on sexual function and quality of life: the TAIM Study

OBJECTIVE

To evaluate treatment of mild hypertension using combinations of diet and low-dose pharmacologic therapies.

DESIGN

Multicenter, randomized, placebo-controlled clinical trial.

SETTING

Three university-based tertiary care centers.

PATIENTS

Patients (697) 21 to 65 years of age with diastolic blood pressure between 90 and 100 mm Hg as well as weight between 110% and 160% of ideal weight.

INTERVENTION

Patients were stratified by clinical center and race and were randomly assigned to one of three diets (usual, low-sodium and high-potassium, weight loss) and one of three agents (placebo, chlorthalidone, and atenolol).

MEASUREMENTS

Changes in measures of sexual problems, distress, and well-being after 6 months of therapy were analyzed.

MAIN RESULTS

Low-dose chlorthalidone and atenolol produced few side effects, except in men. Erection-related problems worsened in 28% (95% CI, 15% to 41%) of men receiving chlorthalidone and usual diet compared with 3% (CI, 0% to 9%) of those receiving placebo and usual diet (P = 0.009) and 11% (CI, 2% to 20%) of those receiving atenolol and usual diet (P greater than 0.05). The weight loss diet ameliorated this effect. The low-sodium diet with placebo was associated with greater fatigue (34%; CI, 23% to 45%) than was either usual diet (18%; CI, 10% to 27%; P = 0.04) or weight reduction (15%; CI, 7% to 23%; P = 0.009). The low-sodium diet with chlorthalidone increased problems with sleep (32%; CI, 22% to 42%) compared with chlorthalidone and usual diet (16%; CI, 8% to 24%; P = 0.04). The weight loss diet benefited quality of life most, reducing total physical complaints (P less than 0.001) and increasing satisfaction with health (P less than 0.001). Total physical complaints decreased in 57% to 76% of patients depending on drug and diet group, and were markedly decreased by weight loss.

CONCLUSION

In general, low-dose antihypertensive drug therapy (with chlorthalidone or atenolol) improves rather than impairs the quality of life; however, chlorthalidone with usual diet increases sexual problems in men.

Systolic Hypertension of the Elderly Program (SHEP). Part 10: Analysis

The SHEP is a randomized, placebo-controlled trial that will follow standard clinical trial principles in analyzing data relating to its proposed hypotheses. The protocol has stated a priori the main objective as well as the secondary subgroup hypotheses. Sample size calculations for SHEP have accounted for dropins to and drop-outs from active therapy as well as for the risk of nonstroke death. The sample size achieved (4,736 participants) should be adequate to address the proposed questions. Monitoring procedures have been described and established. A data and safety monitoring board that uses these procedures is closely following the data from the trial. The board will periodically examine the data to determine whether termination of the study is warranted.

Quality of life on antihypertensive therapy: a randomized double-blind controlled trial of captopril and atenolol

A randomized double-blind study lasting 2 months was performed with either 25 mg captopril twice a day or 50 mg atenolol once a day in 125 patients with established diastolic hypertension (diastolic blood pressure greater than 95 mmHg) identified during a population screening programme of subjects aged less than 65 years. Quality of life was assessed from self-completed questionnaires. A significant fall in diastolic blood pressure occurred with both captopril (106.7 +/- 7.0 to 98.6 +/- 8.6 mmHg) and atenolol (107.4 +/- 7.5 to 98.2 +/- 8.1 mmHg) but there was no difference between the two drugs in the size of the fall. A measure of the number of symptomatic complaints, the symptom complaint rate, decreased with both drugs, by 1.3% for captopril and 3.1% for atenolol, but the difference between the drugs was not significant [1.8%; 95% confidence interval (Cl) - 1.3%, 4.9%]. There was a significant increase in the reporting of cough and runny nose in those on captopril compared with atenolol. A health index increased by 1.1% with captopril in comparison with no change on atenolol (difference 1.1%; 95% Cl - 2.0%, 4.2%). Psychological well-being was measured using the Symptom Rating Test. The improvement in total score was 1.4% with captopril and 2.3% with atenolol. The difference of 0.9% was not statistically significant (95% Cl - 1.2%, 3.0%).(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacologic and nutritional treatment of mild hypertension: changes in cardiovascular risk status

OBJECTIVE

To evaluate the 6-month change in cardiovascular (coronary heart disease) risk as a function of diet and drug therapy for mild hypertension.

DESIGN

Collaborative randomized, controlled clinical trial to assess the efficacy of alternative regimens in treating mild hypertension.

SETTING

Three university-based tertiary care centers-the Trial of Antihypertensive Interventions and Management (TAIM).

PATIENTS

Six hundred and ninety-two men and women ages 21 to 65 years with diastolic blood pressure between 90 and 100 mm Hg and weight between 110% and 160% of ideal weight.

MEASUREMENTS AND MAIN RESULTS

Patients stratified by clinical center and race were randomized into diet (usual, low sodium-high potassium, weight loss) and drug (placebo, chlorthalidone, and atenolol) groups resulting in nine diet plus drug combinations. The cardiovascular risk at 6-month follow-up was estimated relative to baseline in 692 participants using the Framingham Study model. Due to the blood pressure reduction, cardiovascular risk declined from baseline for all treatment groups (except the usual diet plus chlorthalidone group because of increased cholesterol levels). The relative cardiovascular risk at 6 months compared to baseline ranged from 0.83 in the weight loss plus atenolol subgroup to 1.03 in the usual diet plus chlorthalidone subgroup. The active drug plus weight loss groups showed the lowest relative cardiovascular risk at 6 months.

CONCLUSIONS

Mild hypertension was generally reduced to desirable levels within 6 months by monotherapy. Evaluating blood pressure changes together with the risk factors indicated a differential effect on overall cardiovascular risk depending on the diet and drug used. Dietary therapy, particularly weight reduction, was important adjunctive treatment in reducing overall cardiovascular risk.

An illness-death process with time-dependent covariates

A general model for the illness-death stochastic process with covariates has been developed for the analysis of survival data. This model incorporates important baseline and time-dependent covariates in order to make an appropriate adjustment for the transition and survival probabilities. The follow-up period is subdivided into small intervals and a constant hazard is assumed for each interval. An approximation formula is derived to estimate the transition parameters when the exact transition time is unknown. The method developed is illustrated with data from a study on the prevention of the recurrence of a myocardial infarction and subsequent mortality, the Beta-Blocker Heart Attack Trial (BHAT). This method provides an analytical approach with which the effectiveness of the treatment can be compared between the placebo and propranolol treatment groups with respect to fatal and nonfatal events simultaneously.

The effects of verapamil and propranolol on quality of life in hypertension

Quality of life was evaluated in a four-month randomised double-blind trial of verapamil compared with propranolol in the treatment of hypertension in 94 patients in the UK. Scores on a health status index, measuring activity and perceived health, increased in verapamil patients compared to a decrease in propranolol patients (P = 0.01). Measures of psychiatric morbidity also tended to improve with verapamil and deteriorate with propranolol. Propranolol patients reported more symptoms overall compared with verapamil (P less than 0.05). The prevalence of certain symptoms--headaches, weak limbs and slower walking pace, increased significantly with propranolol compared with verapamil, but constipation was more common in verapamil patients (P less than 0.05). After four months, diastolic blood pressure averaged 86.2 mmHg with verapamil and 90.3 mmHg with propranolol (P = 0.02). However, this difference in final blood pressure did not explain the more favourable quality of life scores with verapamil, and the data suggest that health-related well-being is higher with this drug.

Trial of antihypertensive interventions and management. Design, methods, and selected baseline results

The Trial of Antihypertensive Interventions and Management was a multicenter randomized, placebo-controlled trial designed to assess the effectiveness of various combinations of pharmacologic and dietary interventions in the treatment of mild hypertension (diastolic blood pressure 90-100 mmHg). The primary outcome was blood pressure change between baseline and 6 months. The study consisted of a 3 X 3 factorial design wherein participants were randomly allocated to nine drug-diet treatment groups. Drugs included placebo, diuretic, and beta-blocker. Diets were usual, weight loss, and low sodium/high potassium. The basic strategy was to address clinical questions of interest by comparing mean blood pressure changes of selected drug-diet combinations. This paper describes the study including experimental design, sample size considerations, statistical analysis, organizational structure, and baseline findings.

The Systolic Hypertension in the Elderly Program (SHEP): an intervention trial on isolated systolic hypertension. SHEP Cooperative Research Group

The Systolic Hypertension in the Elderly Program (SHEP) is a randomized double-blind placebo-controlled trial to determine if antihypertensive treatment of isolated systolic hypertension (ISH) [systolic blood pressure (SBP) greater than or equal to 160 mmHg, diastolic blood pressure (DBP) less than 90 mmHg] reduces the 5 year incidence of fatal and nonfatal stroke. Between March 1, 1985 and January 15, 1988, 4736 persons (target 4800) with ISH, age 60 years and over, were enrolled. Potential participants met blood pressure (BP) and age criteria. Those on antihypertensive medication prior to enrollment without documented diastolic hypertension had their medication tapered and discontinued, and then met BP criteria (33% of cohort). Stepped-care therapy with chlorthalidone and atenolol (alternative, reserpine) or matching placebos was initiated as first and second steps. At baseline the trial population was 43.1% male, 56.9% female; 13.9% black, 86.1% non-black. Also, the mean age was 71.6 years; the mean SBP was 170.3 mmHg and the mean DBP was 76.6 mmHg; 59.8% had codeable resting electrocardiographic abnormalities. The trial is now in follow-up phase with scheduled termination in 1991.

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.

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.

Systolic blood pressure as an independent predictor of mortality in the Hypertension Detection and Follow-up Program

The Hypertension Detection and Follow-up Program (HDFP) findings demonstrate the predictive value of baseline systolic blood pressure (SBP) and of pulse pressure (PB) in five-year mortality from all causes. Grouping participants into four SBP strata revealed an approximately two-fold increase in age-adjusted mortality rate from SBP stratum I to SBP stratum IV. This effect remained after the contributions of other risk factors were controlled by multivariate analysis. In contrast, baseline diastolic blood pressure (DBP) had little demonstrable effect on mortality in this particular population. The predictive power of pulse pressure was similar to that of SBP. The group mean SBP of every stratum fell progressively during the trial, the change being of greater magnitude in the stepped care (SC) group than in the referred care (RC) group. Also, the reduction in all-cause mortality associated with SC treatment was observed at all levels of baseline SBP. An analysis using life table regression with SBP as a time-dependent variable showed that the postrandomization reduction in SBP was a significant factor in reducing mortality. Similarly, reduced DBP was also contributory. Prospective studies are required to answer definitively the question of the efficacy of treatment of systolic hypertension. Nevertheless, the present analysis of the HDFP data, despite design limitations, supports the advisability of reducing elevated systolic blood pressure.

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.

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.

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.

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.

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.

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.

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.

Training and certification of blood pressure observers

Accurate, reproducible measurements of blood pressure (BP) were central to the goals and objectives of the Hypertension Detection and Follow-Up Program (HDFP), a multicenter clinical trial on the efficacy of pharmacological treatment of individuals with elevated BP. All potential BP observers with or without previous experience in measuring BP were required to undergo a defined training program and meet set performance criteria to be certified to take HDFP BP. Recertification was required twice a year. Originally an audiotape test was used to measure accuracy of BP readings. This approach was later replaced by a videotape test, which proved more realistic and an equally effective tool for long-term quality control. With this technique of certifications, 75% of the individuals taking the test passed on the first attempt and more than 95% passed with one or two attempts. Although agreement for blinded BP duplicates was generally good, the appearance of sound (systolic BP) was identified with greater reproducibility than was the disappearance (diastolic BP). These recertification procedures were of great value in assuring the continued high quality of our BP data.

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%.

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.

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.

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.

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.