Participant attrition from statewide, population-based Survey of the Health of Wisconsin into the longitudinal SHOW COVID-19 cohort

PURPOSE

Longitudinal studies are essential for examining how social and institutional determinants of health, historical and contemporary, affect disparities in COVID-19 related outcomes. The unequal impacts of COVID-19 likely exacerbated selected attrition in longitudinal research. This study examines attrition and survey mode effects in the SHOW COVID-19 study which recruited from a statewide, representative cohort.

MATERIALS & METHODS

Participants were recruited from the Survey of the Health of Wisconsin (SHOW) cohort. Online surveys, or phone interviews, were administered at three timepoints during 2020-2021. The surveys captured social, behavioral, and structural determinants of health and the lived experience. Univariate and multivariate logistic regression was used to examine predictors of participation and survey mode effects.

RESULTS

A total of 2304 adults completed at least one COVID-19 online survey. Participants were more educated, older, and more likely to be female, married, non-Hispanic, and White compared to non-participants. Phone participants were older, less educated, and more likely be non-White, food insecure, and have co-morbidities compared to online participants. Mode effects were seen with reporting COVID-19 beliefs, loneliness, and anxiety.

CONCLUSION

The SHOW COVID-19 cohort offers unique longitudinal data but suffered from selected attrition. Phone interview is an important mode for retention and representation.

Worsening skin lesions but no diagnosis

A diagnosis was arrived at by doing something that the patient's other doctors hadn't: perform a biopsy.

A Mechanized Pediatric Elbow Joint Powered by a De-Based Artificial Skeletal Muscle

To increase the acceptability of exoskeletons, there is growing attention toward finding an alternative soft actuator that can safely perform at close vicinity of the human body. In this study, we investigated the capability of the dielectric elastomer actuators (DEAs), for muscle-like actuation of rehabilitation robots. First, an artificial skeletal muscle was configured using commercially available stacked DEAs arranged in a 3x4 array of three parallel fibers consisting of four DEAs connected in series. The shortening and force generation capabilities of this artificial muscle were then measured. An alternate 3x5 version of this muscle was mounted on the forearm of an upper extremity phantom model to actuate its elbow joint. The actuation capability of this muscle was then tested under various tensile loads, 1 N to 4 N, placed at the center of mass of the forearm+hand of the phantom model. The active range of motion and angular velocity of the phantom model's tip of the hand were measured using a motion capture system. The 3×4 artificial muscle produced 30.47 N of force and 5.3 mm of maximum shortening. The 3x5 artificial muscle was capable of actuating the elbow flexion 19.5º with 16.2 º/s angular velocity in the sagittal plane, under a 1 N tensile load. The active range of motion was substantially reduced as the tensile loads increased, which limits the capability of these muscles in the current upper extremity exoskeleton design.

A Practical Device for the Application of a Diagnostic or Prognostic Function

The application of a diagnostic or prognostic Multiple Logistic Function (MLF) in medical practice may, depending on the complexity of the model, require considerable arithmetic. Various methods for the elimination of such arithmetic, e.g. sets of tables or nomograms, have been proposed. An alternative method of eliminating the necessary arithmetic is described here. It is based on the principle of the familiar slide-rule. As an example, the design of a slide-rule for the evaluation of a diagnostic model for acute myocardial infarction is described. The slide-rule method allows for the evaluation of logistic models with complex linear combinations in the exponent. Adequate devices can be produced at low cost.

Preventing diabetes among Fair Haven families: a community-based approach to quality improvement

In this paper, we describe our efforts to integrate the Diabetes Prevention Program and the Bright Bodies program into a coordinated intensive lifestyle intervention program for families living in Fair Haven, an underserved Hispanic neighborhood in New Haven, Connecticut with high rates of obesity and prediabetes in adults and children.

A way of achieving more rational drug prescribing?

The effect on prescribing of co-operation between four pharmacists and 10 general medical practitioners in west Rotterdam, the Netherlands, was studied using the case-control method. Prescribing statistics provided by the Rotterdam Health Insurance Foundation for the years 1979-1982 were used to examine the effect of co-operation on the number of prescriptions per year, the number of units of supply per year and the cost of drugs supplied. The results show that it is possible to standardise drug therapy used by a group of GPs and pharmacists, that prescribing agreements can be maintained over a number of years and that doctors who co-operate with pharmacists prescribe more rationally and more cheaply than those who do not.

Microstructural and functional connectivity in the developing preterm brain

Prematurely born children are at increased risk for cognitive deficits, but the neurobiological basis of these findings remains poorly understood. Because variations in neural circuitry may influence performance on cognitive tasks, recent investigations have explored the impact of preterm birth on connectivity in the developing brain. Diffusion tensor imaging studies demonstrate widespread alterations in fractional anisotropy, a measure of axonal integrity and microstructural connectivity, throughout the developing preterm brain. Functional connectivity studies report that preterm neonates, children and adolescents exhibit alterations in both resting state and task-based connectivity when compared with term control subjects. Taken together, these data suggest that neurodevelopmental impairment following preterm birth may represent a disease of neural connectivity.

Survival analysis in total joint replacement: an alternative method of accounting for the presence of competing risk

Survival analysis is an important tool for assessing the outcome of total joint replacement. The Kaplan-Meier method is used to estimate the incidence of revision of a prosthesis over time, but does not account appropriately for competing events which preclude revision. In the presence of competing death, this method will lead to statistical bias and the curve will lose its interpretability. A valid comparison of survival results between studies using the method is impossible without accounting for different rates of competing events. An alternative and easily applicable approach, the cumulative incidence of competing risk, is proposed. Using three simulated data sets and realistic data from a cohort of 406 consecutive cementless total hip prostheses, followed up for a minimum of ten years, both approaches were compared and the magnitude of potential bias was highlighted. The Kaplan-Meier method overestimated the incidence of revision by almost 4% (60% relative difference) in the simulations and more than 1% (31.3% relative difference) in the realistic data set. The cumulative incidence of competing risk approach allows for appropriate accounting of competing risk and, as such, offers an improved ability to compare survival results across studies.

Treatment of angina pectoris: associations with symptom severity

OBJECTIVE

To evaluate whether the frequency of anginal attacks in medically treated patients with stable angina is related to the intensity of anti-anginal treatment, the clinical history and coronary anatomy.

METHODS

Analysis of baseline data from the A Coronary disease Trial Investigating Outcome with Nifedipine GITS (ACTION) study, an ongoing placebo-controlled trial in 7669 patients with stable angina pectoris who require anti-anginal treatment.

RESULTS

Prior to randomisation, 8% of 7669 patients had no anginal attacks, 63% had occasional, 22% had regular, 4% had frequent and 3% had daily attacks. Men (79% of all patients) and patients with a history of MI (51%) had less frequent anginal attacks (P<0.0001). The number of coronary angiograms ever performed (70% had at least one angiogram), the extent of angiographic coronary disease (32% of those who had angiography had more than two-vessel disease), a history of peripheral artery disease (12%), the number of anti-anginal drugs used (64% were prescribed two or more such medications) and a history of revascularisation (a history of coronary bypass surgery was present in 23% and of balloon dilatation in 26%) were each positively associated with anginal attack frequency.

CONCLUSIONS

For the majority of patients with chronic stable angina not on a calcium-antagonist, medical treatment with other anti-anginal drugs is sufficient to control symptoms and only a minority of patients are refractory to medical treatment. Invasive treatments for chronic stable angina are only needed in a small proportion where symptoms persist.

Baseline risk as predictor of treatment benefit: three clinical meta-re-analyses

A relationship between baseline risk and treatment effect is increasingly investigated as a possible explanation of between-study heterogeneity in clinical trial meta-analysis. An approach that is still often applied in the medical literature is to plot the estimated treatment effects against the estimated measures of risk in the control groups (as a measure of baseline risk), and to compute the ordinary weighted least squares regression line. However, it has been pointed out by several authors that this approach can be seriously flawed. The main problem is that the observed treatment effect and baseline risk measures should be viewed as estimates rather than the true values. In recent years several methods have been proposed in the statistical literature to potentially deal with the measurement errors in the estimates. In this article we propose a vague priors Bayesian solution to the problem which can be carried out using the 'Bayesian inference using Gibbs sampling' (BUGS) implementation of Markov chain Monte Carlo numerical integration techniques. Different from other proposed methods, it uses the exact rather than an approximate likelihood, while it can handle many different treatment effect measures and baseline risk measures. The method differs from a recently proposed Bayesian method in that it explicitly models the distribution of the underlying baseline risks. We apply the method to three meta-analyses published in the medical literature and compare the results with the outcomes of the other recently proposed methods. In particular we compare our approach to McIntosh's method, for which we show how it can be carried out using standard statistical software. We conclude that our proposed method offers a very general and flexible solution to the problem, which can be carried out relatively easily with existing Bayesian analysis software. A confidence band for the underlying relationship between true effect measure and baseline risk and a confidence interval for the value of the baseline risk measure for which there is no treatment effect are easily obtained by-products of our approach.

Implications of trial results: the potentially misleading notions of number needed to treat and average duration of life gained

Consider a physician advising a patient to start antihypertensive treatment. He has the unenviable task of presenting often conflicting trial data in a comprehensible manner. He must justly represent the known risks and benefits such that his patient can make a reasonably Informed choice. Should the physician cite the number needed to treat or the average duration of life gained to clarify his explanations?

Heart failure treatments: issues of safety versus issues of quality of life

Congestive heart failure is an important cause of morbidity and mortality in western countries. The profound impact that congestive heart failure has on life expectancy and quality of life has been a continuous stimulus for the development of new drugs for the treatment of this condition. Despite favourable effects on (aspects of) quality of life in short term studies, several of these new agents have been shown to reduce survival in mortality trials. However, patients with severe congestive heart failure may experience such incapacitating symptoms that the question should be raised as to whether an improvement in quality of life makes the increased risk of mortality associated with these new agents acceptable. Drugs which improve quality of life at the expense of an increased risk of mortality can be of value in the treatment of patients with severe congestive heart failure. However, this is only the case if the probability of improvement in quality of life and prolongation of life expectancy for those using the drug exceeds the probability of improvement in quality of life and prolongation of life expectancy for those not using the drug. Unfortunately, most clinical trials in which both mortality and quality of life are evaluated fail to provide information on this composite probability. Despite disappointing results of some recent mortality trials on new pharmacological treatments of congestive heart failure, sound and well designed clinical trials on innovative heart failure treatments in which these composite probabilities are also assessed should be carried out.

Relationship between abortions and seroprevalences to selected infectious agents in dairy cows

The aim of this study was to determine whether the occurrence of abortion is related to the seroprevalence of abortion-causing infectious agents. In a cross-sectional study, cattle from dairy farms in Switzerland that were defined as having an abortion problem were divided into two groups: cows with a history of abortion within the previous 3 months (cases) and cows without a history of abortion (controls). A positive titre to Leptospira spp. was associated with an increased probability of being a case (OR = 1.74, 95% CI = 1.21-2.47). There were interactions between Coxiella burnetti titre and parity, and between Chlamydia psittaci and C. burnetti titre and breed. Multiparous cases after the second lactation with a positive titre to C. burnetti were less likely (OR = 0.42, 95% CI = 0.22-0.82) to be cases. Swiss Browns (Swiss Braunvieh and Brown Swiss) with a positive titre to C. psittaci and Swiss Browns with a positive titre to C. burnetti were more likely (OR = 1.63, 95% CI = 1.13-2.37 and OR = 1.79, 95% CI = 1.15-2.78, respectively) to be cases. Parity alone was not associated with the occurrence of abortion.

Design and current status of ACTION: A Coronary disease Trial Investigating Outcome with Nifedipine GITS. Gastro-Intestinal Therapeutic System

AIMS

To present the design of ACTION (A Coronary disease Trial Investigating Outcome with Nifedipine GITS), an ongoing multicentre clinical outcome trial with nifedipine GITS (Gastro-Intestinal Therapeutic System) in patients with stable angina pectoris.

METHODS

At least 6000 patients with optimally treated stable angina without depressed left ventricular function are randomized in equal proportions to either nifedipine GITS or matching placebo (starting dose 30 mg, maintenance dose 60 mg once daily). Patients are followed for at least four years. The primary end-point, to be analyzed by assigned treatment, includes all-cause mortality, acute myocardial infarction, emergency coronary angiography for refractory angina, overt heart failure, debilitating stroke and peripheral revascularization. For this end-point, the trial has a power of 95% to detect a relative risk reduction of 18% at the 5%, level of significance, and is large enough to exclude an excess mortality caused by nifedipine GITS of 3.1 deaths per 1000 years of treatment or greater. The pre-specified early termination rule is more conservative in the case of a beneficial effect than in the case of an adverse effect of nifedipine GITS. The first patient was randomized on 29 November, 1996. By the end of April 1998, about 5200 patients had been started on study medication.

CONCLUSIONS

Results will be available in the autumn of 2003.

The calcium channel antagonist debate: recent developments

Recent contributions to the calcium channel antagonist (CCA) debate concern the recommendations in the Sixth Report of the U.S.A. Joint National Committee on Prevention. Detection, Evaluation and Treatment of High Blood Pressure and raise questions about evidence-based medicine. Also, several studies have recently been published. A 4695-patient placebo-controlled trial showed that the CCA nitrendipine significantly reduces cardiovascular complications in older people with systolic hypertension. A 470-patient trial showed a significantly higher rate of myocardial infarction in hypertensive non-insulin-dependent diabetics treated with the CCA nisoldipine than in those treated with the ACE inhibitor enalapril. Non-experimental data (on 84 093 person-years in total) comparing antihypertensive agents in hypertensive women showed mostly non-significant covariate-adjusted total and cardiovascular mortality differences that are difficult to interpret because of potential residual confounding. One report suggested a relationship between CCAs and suicide. A case-control study (9513 cases, 6492 controls) showed that CCAs are unlikely to cause cancer. The current recommendation remains to start treatment of hypertension with diuretics and beta-blockers, but recent studies support the use of sustained release CCAs in cases in which blood pressure cannot be controlled with other agents.

Action: a 30,000 patient-years double-blind, placebo-controlled trial of nifedipine GITS in stable angina. ACTION Research Group

To assess the overall balance between efficacy and safety of the long-action calcium antagonist nifedipine gastrointestinal therapeutic system (GITS) in patients with stable symptomatic coronary artery disease (CAD), a large multicentre placebo-controlled double-blind trial called ACTION has been mounted (A Coronary Disease Trial Investigating Outcome with Nifedipine GITS). Patients are eligible if they have proven CAD on antianginal treatment in stable clinical condition for at least 3 months without heart failure. The left ventricular ejection fraction must be above 40%. Patients not already on lipid-lowering therapy will be evaluated and such treatment will be started based on current guidelines before randomisation. After washout of an already given calcium antagonist, more than 6000 patients in total will be randomised in equal proportions to either nifedipine GITS 60 mg once daily or placebo. The mean clinical follow-up will be 5 years, with no restrictions on concomitant medication (with the exception of digitalis, calcium antagonists and class III antiarrhythmics). The primary end-point will be survival free of major cardiovascular events (i.e. survival free of acute myocardial infarction, emergency coronary angiography, overt heart failure, stroke and peripheral revascularisation). The study has 95% power to detect a significant (p < 0.05) 18% improvement of this end-point and is of sufficient size to exclude an excess mortality of 3.1 per 1000 patient-years. In this first stable angina trial of this size and scope, 185 centres in Canada, Europe, Israel, Australia and New Zealand will participate. Recruitment will start in November 1996 and is planned to be completed in 2 years.

Sudden cardiac death in patients with hypertension. An association with diuretics and beta-blockers?

The cornerstones of current antihypertensive treatment are diuretics and beta-blockers and the efficacy of these drugs in preventing cardiovascular disease is undisputed. This article focuses on the effect of these 2 drug classes on the incidence of sudden death. Numerous studies have shown that thiazide diuretics have a strong, dosage-dependent potassium-depleting effect, and it has been postulated that this may explain why the reduction in risk of coronary heart disease, observed in hypertension trials, was less pronounced than expected. In 7 trials that included sudden death as an end-point; a pooled risk-ratio of sudden death of 1.5 (95% confidence interval 1.1 to 2.0) was observed when non-potassium-sparing diuretics were compared with placebo. Two recent case-control studies have also strongly indicated that the use of thiazides increases the risk of sudden death. Evidence from trials using potassium-sparing diuretic combinations suggests that these may be better tolerated than thiazide monotherapy. Although it was suggested in the 2 recent case-control studies that recipients of beta-blockers are also at an increased risk of sudden death, further studies are required to confirm this finding, particularly since these drugs have several well-documented cardioprotective effects.

Effect of pimobendan on exercise capacity in patients with heart failure: main results from the Pimobendan in Congestive Heart Failure (PICO) trial

PRIMARY OBJECTIVE

To determine the effects of pimobendan 2.5 and 5 mg daily on exercise capacity in patients with chronic heart failure.

DESIGN

A randomised, double blind, placebo controlled trial of the addition of pimobendan to conventional treatment with a minimum follow up of 24 weeks.

SETTING

Outpatient cardiology clinics in six European countries.

PATIENTS

317 patients with stable symptomatic heart failure, objectively impaired exercise capacity, and an ejection fraction of 45% or lower who were treated with at least an angiotensin converting enzyme inhibitor and a diuretic and who tolerated a test dose of pimobendan.

RESULTS

Compared with placebo, both pimobendan 2.5 and 5 mg daily improved exercise duration (bicycle ergometry) by 6% (P = 0.03 and 0.05) after 24 weeks of treatment. At that time 63% of patients allocated to pimobendan and 59% of those allocated to placebo were alive and able to exercise to at least the same level as at entry (P = 0.5). No significant effects on oxygen consumption (assessed in a subgroup of patients) and on quality of life (assessed by questionnaire) were observed. Pimobendan was well tolerated. Proarrhythmic effects (24-hour electrocardiography) were not observed. In both pimobendan groups combined the hazard of death was 1.8 (95% confidence interval 0.9 to 3.5) times higher than in the placebo group.

CONCLUSIONS

Pimobendan improves exercise capacity in patients with chronic heart failure who are also on conventional treatment. The balance between benefit and risk of treatment with this compound remains to be established however.

Meta-analysis of morbidity and mortality in five exercise capacity trials evaluating ramipril in chronic congestive cardiac failure

In 5 separate exercise capacity trials in similar patients with chronic congestive heart failure performed in Europe, the United States, and South Africa, 627 patients were randomized to ramipril and 428 to placebo. The dose of ramipril ranged from 1.25 to 20 mg/day. Follow-up was at 12 or 24 weeks. None of the trials were designed to assess efficacy with regard to clinical outcome. To assess in the combined experience whether there was an effect of ramipril on mortality, hospitalization, functional classification (New York Heart Association class), and exercise capacity, we pooled data from each trial and performed a mata-analysis. Of the patients randomized to ramipril and placebo, respectively, and based on intention to treat, 14 (2.2%) and 18 (3.8%) patients died (odds ratio 0.60, 95% confidence interval 0.28 to 1.29), and 59 (9.4%) and 67 (14.3%) patients died or were hospitalized (odds ratio 0.68, 95% confidence interval 0.46 to 1.00). The New York Heart Association class improved in 29% and 25% respectively, whereas 8% and 15% deteriorated (p=0.04, based on intention to treat; death and hospitalization considered as deterioration). In ranked comparisons based on intention to treat and with imputation of exercise time as 0 for patients who were unable to exercise because of death or who were hospitalized, exercise capacity was significantly improved by rampril. We concluded that rampiril is likely to have an effect on mortality, morbidity, and functional capacity in patients with chronic congestive heart failure similar to that of other angiotensin-converting enzyme inhibitors.

Diuretics, beta-blockers, and the risk for sudden cardiac death in hypertensive patients

OBJECTIVE

To determine whether the use of non-potassium-sparing diuretics and beta-blockers is associated with an excess risk for sudden cardiac death in hypertensive patients.

DESIGN

Case-control study.

SETTING

Rotterdam, the Netherlands.

PATIENTS

257 case-patients who had died suddenly while receiving drug therapy for hypertension and 257 living controls also receiving drug therapy for hypertension.

MEASUREMENTS

Detailed information on medication use and clinical characteristics of all case-patients and controls was collected from the files of general practitioners. Additional information on medication use was obtained from computerized pharmacy records.

RESULTS

Patients receiving non-potassium-sparing diuretics had an increased risk for sudden cardiac death (relative risk, 1.8 [95% CI, 1.0 to 3.1]) compared with a reference group treated primarily with potassium-sparing diuretics. The corresponding relative risk for beta-blocker use was 1.7 (CI, 1.1 to 2.6). The use of non-potassium-sparing diuretics without beta-blockers was associated with a higher risk for sudden death (relative risk, 2.2 [CI, 1.1 to 4.6]) than was concomitant use of non-potassium-sparing diuretics and beta-blockers (relative risk, 1.4 [CI, 0.6 to 3.0]). The risk for sudden cardiac death among recipients of non-potassium-sparing diuretics was more pronounced in those who had been receiving the diuretic for less than 1 year and in those aged 75 years or younger.

CONCLUSIONS

The use of non-potassium-sparing diuretics and beta-blockers is associated with an increased risk for sudden cardiac death. This association may offset part of the mortality benefit of these drugs in the treatment of hypertension.

Does drug treatment improve survival? Reconciling the trials in mild-to-moderate hypertension

OBJECTIVE

To evaluate whether drug treatment for mild-to-moderate hypertension in middle-aged patients improves survival and to study how the conflicting results of individual trials may be explained.

STUDY SELECTION

A meta-analysis was performed, including seven randomized trials in mild-to-moderate hypertensive (diastolic blood pressure 90-114 mmHg) middle-aged patients.

DATA EXTRACTION

A comparison was made between all-cause mortality and fatal coronary heart disease and stroke in the intervention and control group of the individual trials, using a method of meta-analysis based on weighted linear regression.

RESULTS

In trials with a high all-cause mortality rate (> 6 per 1000 patient-years) in the control group, antihypertensive drug treatment increased life expectancy. When all-cause mortality in the control group was low, treatment showed no effect or even an opposite effect. Findings on mortality from coronary heart disease were similar, whereas drug treatment decreased stroke mortality irrespective of the incidence of stroke in the control group.

CONCLUSIONS

Drug treatment for mild-to-moderate hypertension in middle-aged patients may reduce all-cause mortality and the risk of fatal coronary events when treatment is initiated in those beyond a certain baseline mortality risk. Drug treatment in hypertensive patients at a lower mortality risk has no influence on or may even increase mortality.

Do non-potassium-sparing diuretics increase the risk of sudden cardiac death in hypertensive patients? Recent evidence

Whether non-potassium-sparing diuretics (NPSD) increase the risk of sudden cardiac death in hypertensive patients has been vigorously debated. Diuretic-induced potassium or magnesium depletion leading to cardiac arrhythmias has been suggested as the underlying mechanism. A clear dose-response relationship between NPSD and the reduction in serum K+ exists. Data regarding serum Mg++ and intracellular K+ and Mg++ are too limited to allow conclusions. NPSD seem to increase the risk of ventricular arrhythmias among hypertensive patients with clinical evidence of heart disease, but the number of studies is small. The findings among patients without evidence of heart disease are less conclusive. The interpretation of the studies on electrolyte changes and arrhythmias following diuretic therapy is obscured by the fact that only a minority of studies included a randomly allocated placebo-treated control group. The large hypertension trials provide the strongest evidence that NPSD for hypertension may induce sudden death. Although blood pressure lowering may be expected to reduce the incidence of sudden cardiac death, the incidence in the NPSD group is similar to or even higher than that in the control group in 9 of 10 trials. We conclude that the beneficial effect of NPSD therapy for hypertension is partly offset by an excess risk of sudden death. Thus, alternative drugs, notably potassium-sparing diuretics or beta-blockers, could be preferred as antihypertensive drugs of first choice, although the efficacy of beta-blockers in older patients has recently been challenged.

Risk factors for seizure recurrence in children with febrile seizures: a pooled analysis of individual patient data from five studies

To reassess the relations between postulated risk factors and seizure recurrence after a first febrile seizure (FS), the individual data from five follow-up studies that used similar definitions of FSs and risk factors were pooled and reanalyzed. The risk of frequent recurrent seizures and of the occurrence of complex seizures in previously healthy, untreated children was studied. Seizure recurrence hazard was described as a function of the child's attained age. The influence of various risk factors on the recurrence hazard was assessed, with control for other factors. Of a total of 2496 children with 1410 episodes of recurrent seizures, 32% had one, 15% had two, and 7% had three or more recurrent seizures after a first FS; 7% had a complex seizure. The hazard of recurrent seizures was highest between the ages of 12 and 24 months. After a first and a second recurrence, the risk of further FSs was two and two and one-half times higher, respectively. A history of febrile or unprovoked seizures in a first-degree family member and a relatively low temperature at the time of the first seizure were also associated with an increased risk of subsequent recurrences. Young age at onset (< 12 months), a family history of unprovoked seizures, and a partial initial FS were all associated with an increased risk of complex seizures. A higher recurrence rate in clinic-based studies compared with population-based studies could not be explained by a difference in the presence of the risk factors studied. Thus other factors must influence seizure recurrence after an initial FS.

Exercise testing as outcome in congestive heart failure trials. Design considerations when interpreting results

In addition to standard features of clinical trial design such as randomisation and double-blinding, sensitivity to drug effects is an important consideration when conducting exercise capacity trials in patients with heart failure. Two issues need to be addressed in this context. Firstly, it is important to enrol patients who are potential responders. Patients who have, for their age and sex, normal exercise capacity are unlikely to improve, even when given a drug that has a positive effect on exercise capacity. In addition, those patients who remain clinically stable following withdrawal of their previous drug therapy are unlikely to respond subsequently to an experimental drug with a similar mechanism of action. Secondly, failure to complete scheduled exercise tests during follow-up, prompting a 'per-protocol' analysis of results, may mask the drug's actual effect. To avoid this, an 'intention-to-treat' approach to data collection and analysis, with appropriate allowance made for missing test data, should be adopted.

Contribution of the 24 hour electrocardiogram to the prediction of sudden coronary death

BACKGROUND

Sudden coronary death is a major public health issue. The identification of patients at high risk should therefore be as efficient as possible. This study compares simple and more elaborate risk stratification procedures.

METHODS

Risk functions for the prediction of sudden death were determined in a population of 6693 consecutive patients who had 24 hour electrocardiography for various indications. The functions were based on the clinical and electrocardiographical data on 245 patients who died suddenly during 2 year follow up and 467 patients randomly drawn from the total study population.

RESULTS

The model based on history (age, sex, myocardial infarction, congestive heart failure, palpitation, syncope, use of diuretics, and use of nitrates), 12 lead electrocardiography (major intraventricular conduction defect, T wave abnormality, and ST depression > or = 0.05 mV), and standard rhythm analysis of 24 hour electrocardiography (ventricular tachycardia, frequent premature atrial complexes, sinus tachycardia (> 150 min-1), and atrial fibrillation) was almost as efficient in the prediction of sudden death as extended models that also contained information from exercise testing, echocardiography, ventriculography, and computer-aided re-analysis of 24 hour electrocardiography (QT and RR interval variability).

CONCLUSIONS

These results indicate that additional information from advanced function tests does little to increase the efficiency of prediction of sudden coronary death over that of tests based on history, the standard 12 lead electrocardiogram, and 24 hour electrocardiography.

Left ventricular systolic and diastolic function, and exercise capacity six to eight weeks after acute myocardial infarction. The DEFIANT Study Group. Doppler Flow and Echocardiography in Functional Cardiac Insufficiency: Assessment of Nisoldipine Therapy

Echocardiographic and Doppler-derived measurements of left ventricular (LV) function at rest were examined as predictors of maximal bicycle exercise capacity in a homogeneous group of 115 patients with mild to moderate LV dysfunction (ejection fraction 22 to 56%, median 43%) participating in the DEFIANT study of nisoldipine after acute myocardial infarction. Although the relations were not exact, peak exercise work load 7 weeks after infarction correlated with measurements of diastolic LV function at rest. Exercise work load was inversely related to peak late diastolic transmitral blood flow velocity (A wave) (slope -86.6; 95% confidence interval -120.9 to -52.2) and directly to the E/A ratio (slope 20.5; 95% confidence interval 6.0 to 35.1). The relations between exercise work load and peak late diastolic flow velocity remained significant after correction for age, sex, heart rate at rest, and use of beta-blocking drugs or nisoldipine. There was no relation between peak exercise work load and peak early diastolic transmitral flow velocity (E wave), isovolumic relaxation period or deceleration time. Measurements of systolic LV function (LV end-diastolic and end-systolic volumes, and ejection fraction, stroke volume and cardiac index) were also not significant as predictors of exercise capacity.

QT interval variables from 24 hour electrocardiography and the two year risk of sudden death

OBJECTIVE

To study the effects of variability in the duration of the QT interval corrected for heart rate (QTc) on the occurrence of sudden death.

DESIGN

Nested case-referent study.

SUBJECTS

Cohort of 6693 consecutive patients who underwent 24 hour electrocardiography and were followed up for two years. Risk implications of QTc interval variables were studied in patients without evidence of cardiac dysfunction or of an intraventricular conduction defect (104 died suddenly and 201 patients were randomly drawn from the study cohort).

MAIN OUTCOME MEASURES

Mean QTc interval duration and variation in QTc duration over time correlated with occurrence of sudden death.

RESULTS

Patients with a prolonged mean QTc over 24 hours (> or = 440 ms) had a 2.3 times (95% confidence interval 1.3 to 4.5) higher risk of dying suddenly than patients with a normal mean QTc (400-440 ms); patients with a shortened mean QTc (< 400 ms) also had a higher risk (relative risk 2.4 (1.4 to 4.3)). Patients with low (< 20 ms) and high (> or = 25 ms) long term variation in QTc duration had an increased risk of dying suddenly compared with those with intermediate variation (20-25 ms) (relative risks 2.2 (1.2 to 4.2) and 2.3 (1.4 to 4.2) respectively). The relative risks for low and high short term variation were not significantly raised.

CONCLUSIONS

A prolonged and a shortened mean QTc interval over 24 hours was associated with a more than twofold risk of sudden death compared with intermediate mean QTc values (400-440 ms). Neither short nor long term variability in QTc had a distinct relation with the risk of sudden death.

Heart rate variability from 24-hour electrocardiography and the 2-year risk for sudden death

BACKGROUND

Low heart rate variability has been implicated as a risk factor for sudden death. However, no large epidemiological studies using sudden death as an outcome event have been reported.

METHODS AND RESULTS

A total of 6,693 consecutive patients who underwent 24-hour ambulatory ECG were followed up for 2 years; of these, 245 patients died suddenly. Clinical data at the time of 24-hour ambulatory ECG were collected for all patients who died suddenly and for a random sample of 268 patients from the study cohort. In all patients in sinus rhythm with or without occasional supraventricular arrhythmias at the 24-hour ECG (193 patients who died suddenly and 230 patients from the sample), heart rate variability parameters were derived. Patients with low short-term RR interval variability (mean during 24 hours of per-minute standard deviations [SD] of RR intervals < 25 msec) had a 4.1-fold higher risk (95% confidence interval [CI], 2.6, 8.1) for sudden death than patients with high short-term variability (> or = 40 msec); after adjustment for age, evidence of cardiac dysfunction, and history of myocardial infarction, the relative risk was 2.6 (95% CI, 1.4, 5.1). The crude relative risk of long-term RR interval variability (SD during 24 hours of per-minute means of RR intervals < 8 msec) was 4.4 (95% CI, 2.6, 7.7); after adjustment for the same risk factors, it was 2.2 (95% CI, 1.2, 4.1). Patients with a minimum heart rate > or = 65 beats per minute had a double risk of sudden death compared with those with a minimum heart rate < 65 beats per minute (adjusted relative risk, 2.1; 95% CI, 1.3, 3.6).

CONCLUSIONS

These findings support the theory that patients with low parasympathetic activity (low short-term RR interval variability) have an increased risk for sudden death independent of other risk factors.

Cardiovascular risk and all-cause mortality; a 12 year follow-up study in The Netherlands

To assess the contribution of cardiovascular risk indicators to all-cause mortality, we used data from a follow-up study conducted in the Netherlands since 1975. Of 6,057 participants aged 20 years or over at the start of the study, 9.5% died during the 9 to 12 year follow-up period. Risk indicators independently related to all-cause mortality were age and diabetes mellitus in both sexes; pulse rate, smoking habits, antihypertensive drug use and a history of myocardial infarction most clearly in men; and body mass index and systolic blood pressure in women. A larger body mass index was associated with a gradual decrease in mortality probability. The risk of death for women in the highest quartile of body mass index (> 26.4 kg/m2) relative to those in the lowest quartile (< 21.9 kg/m2) was 0.56 (95% confidence limits 0.36 and 0.87). Serum cholesterol level showed no association with overall mortality. Risk functions were calculated to predict an individual's probability of dying within 11.5 years as a function of the level of cardiovascular risk indicators. Our findings suggest that the major cardiovascular risk indicators, apart from affecting cardiovascular morbidity and mortality, also influence all-cause mortality. Consequently, favourable changes in these characteristics might lead to an increase in life expectancy. The maximum individual benefit to be expected from these changes may be estimated using the risk functions derived from our data.

Prediction of mortality following hospital discharge after thrombolysis for acute myocardial infarction: is there a need for coronary angiography? European Cooperative Study Group

The role of coronary angiography before hospital discharge after myocardial infarction was assessed in 1043 hospital survivors of the alteplase/placebo and the alteplase/PTCA trial of the European Cooperative Study Group. Forty-two of 1043 patients (4.0%) died after 1 to 489 days after predischarge coronary angiography. In survivors, follow-up ranged from 34 to 1106 days. In a stepwise multivariate regression model (Cox), use of diuretics and/or digitalis, a history of previous infarction and age exceeding 60 years were retained in the model with clinical data only. In addition, inability to perform exercise testing and less than 30 mmHg exercise-induced systolic blood pressure increase were selected by multivariate analysis. Large enzymatic infarct size, radionuclide left ventricular ejection fraction below 40%, and multivessel disease were also determinants of mortality after hospital discharge. The risk function, including coronary angiography, performed no better in late mortality prediction than functions based on clinical data and non-invasive testing. Patients without a history of previous infarction, not treated with diuretics and/or digitalis and with a systolic blood pressure increase of 30 mmHg or more during exercise had an excellent survival (98.6%) in the first year after hospital discharge, irrespective of whether symptoms of recurrent ischaemia occurred. This low risk group formed 47% of the total patient population and does not benefit from coronary angiography.

Seizures and fever: can we rule out meningitis on clinical grounds alone?

A study was done of 309 children seen in two ERs with a first seizure and fever to assess whether meningitis could be recognized using readily available clinical information. Among these children, 23 (7%) cases of meningitis were diagnosed. A group of 69 children with seizures and fever but no meningitis served as controls. Signs from ER examinations that discriminated between children with and those without meningitis were: petechiae, nuchal rigidity, coma, persistent drowsiness, ongoing convulsions, and paresis or paralysis; 21 cases were thus identified. Two children with a suspicious history but none of these signs proved to have meningitis. Children whose seizures showed no complex features and whose febrile illness revealed no suspicious features did not have meningitis. Our results indicate that based on available clinical data, meningitis can be ruled out in children presenting with seizures and fever; thus, there is no need for routine investigation of cerebrospinal fluid.

Recombinant tissue-type plasminogen activator and immediate angioplasty in acute myocardial infarction. One-year follow-up. The European Cooperative Study Group

BACKGROUND

The European Cooperative Study Group conducted two randomized trials in patients with suspected myocardial infarction to assess the effect of 100 mg single-chain recombinant tissue-type plasminogen activator (rt-PA, alteplase) on enzymatic infarct size, left ventricular function, morbidity and mortality relative to placebo (alteplase/placebo trial) and to assess the effect of immediate percutaneous transluminal coronary angioplasty (PTCA) in addition to alteplase (alteplase/PTCA trial). One-year follow-up results are reported.

METHODS AND RESULTS

In the alteplase/placebo trial, 721 patients with chest pain of less than 5 hours and extensive ST-segment elevation were allocated at random to 100 mg alteplase or placebo (double-blind) over 3 hours. In the alteplase/PTCA trial, 367 similar patients received alteplase and subsequently were allocated at random to immediate coronary angiography and angioplasty of the infarct-related vessel or control. All patients received aspirin and intravenous heparin. In the alteplase/placebo trial, mortality during the first year was reduced by 36% with alteplase (from 9.3% to 5.6%; difference, -3.7%; 95% confidence interval, -7.5% to 0.2%). Revascularization was performed more frequently after alteplase, and more patients in the alteplase group were in New York Heart Association functional class I or II. Reinfarction tended to occur more frequently after alteplase than after placebo. In the alteplase/PTCA trial, reinfarction was less common after immediate PTCA, and revascularization procedures were less frequent. However, this benefit was offset by a high rate of immediate reocclusion and early recurrent ischemia and by higher mortality at 1 year (9.3% versus 5.4%; difference, 3.9%; 95% confidence interval, -1.5% to 9.2%) in the invasive group. In a multivariate analysis of 1,043 hospital survivors, mortality after discharge was related to coronary anatomy, left ventricular function, age, and previous infarction but not to initial treatment allocation. Reinfarction after hospital discharge tended to be more common after alteplase and related to coronary anatomy.

CONCLUSIONS

Benefit from treatment with alteplase, heparin, and aspirin is not diminished at 1 year. Routine immediate PTCA does not confer additional benefit. Prognosis after hospital discharge mainly is determined by coronary anatomy and residual left ventricular function and is unrelated to initial treatment assignment.

[Risk factors for the occurrence of recurrent convulsions following an initial febrile convulsion]

The results of a follow up study of 155 Dutch children who visited the emergency room of an urban paediatric hospital after experiencing their first febrile seizure are presented. Median follow up time was 38 months (range 27-60). Of these 155 initially untreated children 58 (37%) suffered at least one, 47 (30%) at least two and 27 (17%) at least three recurrent seizures. The recurrence hazard after any seizure was highest in the first six months, and dropped markedly after 6 months without seizures. The effect of the various postulated risk factors on the occurrence of any recurrent seizure and three or more recurrences was assessed. A first degree family history of febrile or nonfebrile seizures appears to be a predictor of multiple recurrences; an age of at least 30 months and a temperature of 40.0 degrees C or higher at the initial seizure are associated with a decreased risk. Several factors act together on the risk of recurrent seizures, sometimes in opposite directions. By considering the action of all relevant factors (age at onset, family history and features of the initial febrile seizure) subgroups of children with one year seizure recurrence rates as low as 15% and as high as 48% were identified.

Seizure recurrence after a first febrile seizure: a multivariate approach

The results are presented of a follow-up study of 155 Dutch children after the first febrile seizure. Of these initially untreated children 37 per cent had had at least one, 30 per cent at least two and 17 per cent at least three subsequent seizures. The vulnerable period for recurrent seizures after the first febrile seizure was between 12 and 24 months, whereafter the risk was four to five times lower; after any seizure the risk was highest within the first six months, declining steadily after six months without seizures. A first-degree family history of any type of seizure predicted multiple recurrences; an age of at least 30 months and a temperature of greater than or equal to 40 degrees C at initial seizure were associated with reduced risk. Factors in combination influenced the risk of recurrent seizures, sometimes in opposite ways.

Primary prevention in hypertension. Valid conclusions from observational studies

Relatively few observational (i.e., nonexperimental) studies have been conducted to examine the role of antihypertensive drug therapy in the primary prevention of coronary heart disease. To draw valid conclusions from experimental or observational studies, internal validity should be ensured. In particular, similarity of "extraneous" effects, of information, and of prognosis between the treatment groups compared in a particular study is needed. Because allocation of participants to antihypertensive drug therapy in observational studies is nonrandomized by definition, special efforts should be made to achieve comparability of prognosis, that is, to avoid "confounding by indication." Follow-up and case-control studies, the two main types of observational studies, also offer certain advantages over randomized clinical trials, particularly when different classes of drugs are compared. Although few valid observational studies on the efficacy of drug therapy for hypertension in the primary prevention of first coronary events have been published, the available data suggest that beta-blockers might confer greater protection than other drug regimens. However, more evidence is needed to confirm these findings. It is concluded that observational studies could play an increasing role in the assessment of the role of antihypertensive therapy in the primary prevention of coronary heart disease when the inherent potentials and pitfalls of these studies are appreciated.

The effects of nisoldipine on the total ischaemic burden: the results of the ROCKET study

This study was designed to examine the effects of nisoldipine (relative to placebo), a new dihydropyridine calcium entry blocking agent, in the treatment of silent ischaemia in conventional doses. A total of 409 patients with proven coronary artery disease were screened and of this 64 had at least six episodes or a total duration of 30 min of ST segment depression (1 mm lasting at least 1 min) over 48 h. Fifty-two patients ultimately completed a randomized double-blind cross-over study comparing nisoldipine 5 mg twice a day, nisoldipine 10 mg daily and placebo. There was a reduction in the ST segment integral and number of episodes of ST segment depression when compared to placebo on treatment with nisoldipine 5 mg twice a day and nisoldipine 10 mg daily. However, the confidence limits were wide and crossed the no-treatment effect line. In addition, the nisoldipine doses neither affected the circadian distribution of ischaemic episodes nor caused an alteration of the workload achieved either at peak exercise or at 1 mm ST segment depression measured 24 h after nisoldipine 10 mg or 12 h after nisoldipine 5 mg. We conclude that frequent silent ischaemia in patients with proven coronary artery disease is relatively uncommon; it accounts for approximately 16% of patients with positive exercise. In these patients nisoldipine, given as 5 mg twice a day and 10 mg daily, showed no significant therapeutic effects, either on the frequency or severity of silent ischaemia. New formulations of slow release nisoldipine are consequently being developed so that a fuller 24 h therapeutic profile may be obtained.

QTc prolongation measured by standard 12-lead electrocardiography is an independent risk factor for sudden death due to cardiac arrest

BACKGROUND

QTc prolongation has been implicated as a risk factor for sudden death; however, a controversy exists over its significance.

METHODS AND RESULTS

In the Rotterdam QT Project, 6,693 consecutive patients who underwent 24-hour ambulatory electrocardiography were followed up for 2 years; of these, 245 patients died suddenly. A standard 12-lead electrocardiogram and clinical data at the time of 24-hour ambulatory electrocardiography were collected for all patients who died suddenly and for a random sample of 467 patients from the study cohort. In all patients without an intraventricular conduction defect (176 patients who died suddenly and 390 patients from the sample), QT interval duration was measured in leads I, II, and III and corrected for heart rate with Bazett's formula (QTc). In patients without evidence of cardiac dysfunction (history of symptoms of pump failure or an ejection fraction less than 40%), QTc of more than 440 msec was associated with a 2.3 times higher risk for sudden death compared with a QTc of 440 msec or less (95% confidence interval: 1.4, 3.9). In contrast, in patients with evidence of cardiac dysfunction, the relative risk of QTc prolongation was 1.0 (0.5, 1.9). Adjustment for age, gender, history of myocardial infarction, heart rate, and the use of drugs did not alter these relative risks.

CONCLUSIONS

These data indicate that in patients without intraventricular conduction defects and cardiac dysfunction, QTc prolongation measured from the standard electrocardiogram is a risk factor for sudden death independent of age, history of myocardial infarction, heart rate, and drug use. In patients with cardiac dysfunction, QTc duration is not related to the risk for sudden death.

Reasons for the lack of benefit of immediate angioplasty during recombinant tissue plasminogen activator therapy for acute myocardial infarction: a regional wall motion analysis. European Cooperative Study Group

Regional ventricular wall motion analysis utilizing three different methods was performed on predischarge left ventriculograms from 291 of 367 patients enrolled in a randomized trial of single chain recombinant tissue-type plasminogen activator (rt-PA), aspirin and heparin with and without immediate angioplasty in patients with acute myocardial infarction. With univariate analysis, no difference in regional wall motion variables between the two treatment groups was observed. However, with individual baseline risk assessment by multivariate linear regression analysis using baseline characteristics known to be related to left ventricular function after thrombolytic therapy or outcome of coronary angioplasty, or both, an excess of high risk patients in the invasive treatment group was detected. To adjust for this unequal distribution of baseline risk, multivariate linear regression analysis was performed. No benefit of immediate coronary angioplasty was observed after adjustment. Reocclusion or reinfarction, or both, occurred more frequently in the invasive than in the noninvasive treatment group (18% versus 13%, respectively). Among patients with a patent infarct-related vessel on angiography between days 10 and 22 and without reinfarction before angiography, there was a trend toward benefit from the invasive strategy, indicating that reocclusion and reinfarction might be responsible for the lack of benefit of the invasive strategy. This implies that immediate coronary angioplasty may be beneficial in selected patients, provided that these complications can be prevented.

Medical management of unstable angina. What have we learned from the randomized trials?

Because of the absence of a generally accepted definition of unstable angina, the clinical context of drug trials for this condition has varied from trial to trial. Early- versus late-entry trials must be distinguished, and the possibility of a modification of effect caused by the nature of drug therapy already given when the patient became unstable or by concomitant treatment in addition to experimental treatment must be taken into account. These factors cannot be overlooked when the results from a limited number of reported trials are pooled together. The largest early-entry trial with a beta-blocker and a calcium antagonist was the Holland Interuniversity Nifedipine/metoprolol Trial (HINT), which enrolled patients with suspected unstable angina diagnosed at coronary care unit admission. HINT results showed that unstable angina cannot be reliably differentiated from evolving myocardial infarction (MI) in this particular context and that there are few early MIs that could have been prevented. In patients who were not already taking a beta-blocker, metoprolol reduced the incidence of acute MI or recurrent ischemia, and there was no benefit of nifedipine. On the other hand, the addition of nifedipine was effective in patients whose conditions became unstable despite maintenance treatment with a beta-blocker. Thus, previous beta-blockade modified the effect of the calcium antagonist studied. Based on evidence from HINT and other trials, it is concluded that beta-blockers should be used as the first-line treatment in patients with unstable angina and that a calcium antagonist should be added when patients remain unstable despite beta-blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

[Reliability of blood pressure measurements; comparison of an electronic meter and a mercury manometer in family practice]

The Riva-Rocci indirect method of measuring the blood pressure carries a number of sources of error. A report is presented of a study of the serviceability of an electronic blood pressure meter as compared with the conventional mercury manometer. Seventy-six paired measurements were carried out in patients selected at random using an electronic blood pressure meter and a mercury manometer meeting all Health Council requirements. The systematic error and the incidental error in both measuring procedures were compared. The differences found were so slight as to be negligible in practice. It is concluded that the electronic blood pressure meter in practice constitutes an acceptable substitute for the conventional mercury manometer.

Multicentre European trials: their design, execution and relevance

Multicentre randomized clinical trials in Europe over the past decade have made a major contribution to the practice of cardiology and will increasingly do so when the Single Europe Act becomes a fact of life in 1992. The arguments for independent scientifically based research organizations and their role in the area of coronary artery disease are outlined. These include cost-benefit considerations, the science of clinical trials, data acquisition techniques and data management requirements. The role of the pharmaceutical industry in relation to the investigator-trialist is discussed. A critique of the current fashion 'Big is beautiful', with arguments against 'simplicity' and 'large size' and the need for 'credibility' is provided. Applicability of data from trials and their economic usefulness and validity in terms of sound pathophysiological hypotheses are also discussed and illustrated by using the CABRI trial as an example.

Large trials with simple protocols: indications and contraindications

The design of a clinical trial derives from its objective, which in its turn is dictated by the needs of clinical practice. Therefore, a common condition, a simple treatment, and a simple outcome measure are opportunities rather than design options. The argument that the direction of the net treatment effect can be expected to be similar across patient subgroups is inconsistent with biologic reality, and may misguide interpretation of both individual and pooled trial results. If no data on patient characteristics are recorded, scientific generalization is hampered and there is limited opportunity to learn about mechanisms of action and about specific indications and contraindications. If the treatment influences an intermediary outcome, which is assumed to have a causal role in the disease process that the treatment eventually seeks to influence, the effect on the intermediary outcome is of great importance--for clinical practice is very much centered around this outcome and the effects on intermediary outcomes may serve as an aid in explaining why there is an effect or why not. In conclusion, there are some research questions that may warrant large and simple trials, but many clinically very relevant research questions require a more complex trial design.