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S Pocock

Publications and source records attributed to S Pocock.

17 recordsLinked to original sources
PubMed2000

Risks of untreated and treated isolated systolic hypertension in the elderly: meta-analysis of outcome trials.

BACKGROUND: Previous meta-analysis of outcome trials in hypertension have not specifically focused on isolated systolic hypertension or they have explained treatment benefit mainly in function of the achieved diastolic blood pressure reduction. We therefore undertook a quantitative overview of the trials to further evaluate the risks associated with systolic blood pressure in treated and untreated older patients with isolated systolic hypertension METHODS: Patients were 60 years old or more. Systolic blood pressure was 160 mm Hg or greater and diastolic blood pressure was less than 95 mm Hg. We used non-parametric methods and Cox regression to model the risks associated with blood pressure and to correct for regression dilution bias. We calculated pooled effects of treatment from stratified 2 x 2 contingency tables after application of Zelen's test of heterogeneity. FINDINGS: In eight trials 15 693 patients with isolated systolic hypertension were followed up for 3.8 years (median). After correction for regression dilution bias, sex, age, and diastolic blood pressure, the relative hazard rates associated with a 10 mm Hg higher initial systolic blood pressure were 1.26 (p=0.0001) for total mortality, 1.22 (p=0.02) for stroke, but only 1.07 (p=0.37) for coronary events. Independent of systolic blood pressure, diastolic blood pressure was inversely correlated with total mortality, highlighting the role of pulse pressure as risk factor. Active treatment reduced total mortality by 13% (95% CI 2-22, p=0.02), cardiovascular mortality by 18%, all cardiovascular complications by 26%, stroke by 30%, and coronary events by 23%. The number of patients to treat for 5 years to prevent one major cardiovascular event was lower in men (18 vs 38), at or above age 70 (19 vs 39), and in patients with previous cardiovascular complications (16 vs 37). INTERPRETATION: Drug treatment is justified in older patients with isolated systolic hypertension whose systolic blood pressure is 160 mm Hg or higher. Absolute benefit is larger in men, in patients aged 70 or more and in those with previous cardiovascular complications or wider pulse pressure. Treatment prevented stroke more effectively than coronary events. However, the absence of a relation between coronary events and systolic blood pressure in untreated patients suggests that the coronary protection may have been underestimated.

Aged↗
PubMed2000

Analyzing data with clumping at zero. An example demonstration.

This article demonstrates the use of two approaches to analyzing the relationship of multiple covariates to an outcome which has a high proportion of zero values. One approach is to categorize the continuous outcome (including the zero category) and then fit a proportional odds model. Another approach is to use logistic regression to model the probability of a zero response and ordinary least squares linear regression to model the non-zero continuous responses. The use of these two approaches was demonstrated using outcomes data on hours of care received from the Springfield Elder Project. A crude linear model including both zero and non-zero values was also used for comparison. We conclude that the choice of approaches for analysis depends on the data. If the proportional odds assumption is valid, then it appears to be the method of choice; otherwise, the combination of logistic regression and a linear model is preferable.

Activities of Daily Living↗
PubMed1999

Identification of risk factors in hypertensive patients: contribution of randomized controlled trials through an individual patient database.

BACKGROUND: Predicting individual risk is needed to target preventive interventions toward people with the highest probability of benefit over a given time period. We assessed which prognostic factors should be used in predicting risk for hypertensive patients and in searching for treatment modifiers. METHODS AND RESULTS: Data from 24 390 hypertensive participants who constituted the control groups from 8 controlled trials (1726 deaths over 5 years) were analyzed in multivariate survival models. Outcomes were coronary heart disease death, stroke death, and cardiovascular death. We explored systematically the heterogeneity of results between trials. Left ventricular hypertrophy was electrocardiographically confirmed to be a powerful risk factor and should be included in risk scoring. Height, glomerular filtration rate, and serum uric acid deserve further exploration. Body mass index and heart rate were not confirmed as independent cardiovascular risk factors in this population. The association between male sex and coronary heart disease death was significantly stronger in British cohorts. The lack of prognostic value of diastolic blood pressure was explained by an interaction with age, with a positive association before 65 years and a negative association thereafter. Previous antihypertensive treatment was a significant risk factor. CONCLUSIONS: Clinical trials provide valuable information for risk prediction. Carefully exploring the heterogeneity among trials is a way to assess the generalizability of findings. This approach, if systematically performed, should increase the ability to identify risk modifiers and to predict individual therapeutic benefit.

Age Factors↗
PubMed1999

Evaluation of antiarrhythmic drug efficacy in patients with an ICD. Unlimited potential or replete with complexity and problems?

A report from a Study group, proposed by A. J. Camm, London, of the Working Groups on Arrhythmias and Cardiac Pacing of the European Society of Cardiology; co-sponsored by the North American Society of Pacing and Electrophysiology. The Study Group was convened on 29 August 1997 at Saltsjöbaden, near Stockholm. The meeting was chaired by A. J. Camm, London, and C. M. Pratt, Houston. Based on the presentation and discussions, a first draft of the documents was prepared by C. Pratt and J. Camm which was then circulated to all members three times for their review. All members of the Study Group approved the final manuscript. This report represents the opinion of the members of this Study Group and does not necessarily reflect the official position of either society.The meeting of the Study Group was made possible by unrestricted educational grants from Medtronic, Guidant, Proctor & Gamble, Berlex and Sanofi.Also, presented, in part, at the Cardio-Renal Drugs Advisory Board meeting of the Food and Drug Administration, Bethesda, Maryland, on 30 April 1999.

Anti-Arrhythmia Agents↗
PubMed1999

Evaluation of antiarrhythmic drug efficacy in patients with an ICD: unlimited potential or replete with complexity and problems?

There are a number of novel ways in which implantable cardioverter defibrillator (ICD) endpoints can be used in clinical trials to evaluate antiarrhythmic drugs. The advances in ICD technology (storage, retrieval, and accurate interpretation of ICD electrograms) expand the potential to include the use of an ICD endpoint as a clinical surrogate for sudden death. The ICD also provides the necessary safety net to test new drugs. The frequent need for antiarrhythmic drugs in patients already fitted with an ICD (e.g., for atrial fibrillation) necessitates knowledge of the drugs' effect on defibrillator threshold. There are interpretative problems and challenges associated with all types of ICD trials. A particular difficult issue is the degree to which the results of data on antiarrhythmic drug efficacy and safety acquired in the context of an ICD endpoint trial might be extrapolated to patient populations in which the device is not used. These and other challenging issues are discussed, with the goal of enhancing the design and interpretation of clinical trials featuring ICD endpoints.

Anti-Arrhythmia Agents↗
PubMed1997

Effect of antihypertensive drug treatment on cardiovascular outcomes in women and men. A meta-analysis of individual patient data from randomized, controlled trials. The INDANA Investigators.

BACKGROUND: Trials of drug therapy for hypertension have shown that such therapy has a clear overall benefit in preventing cardiovascular disease. Although these trials have included slightly more women than men, it is still not clear whether treatment benefit is similar for both sexes. OBJECTIVE: To quantify the average treatment effect in both sexes and to determine whether available data show significant differences in treatment effect between women and men. DESIGN: Subgroup meta-analysis of individual patient data according to sex. Analysis was based on seven trials from the INDANA (INdividual Data ANalysis of Antihypertensive intervention trials) database and was adjusted for possible confounders. PATIENTS: 20,802 women and 19,975 men recruited between 1972 and 1990. INTERVENTIONS: Primarily beta-blockers and thiazide diuretics. RESULTS: In women, treatment effect was statistically significant for stroke (fatal strokes and all strokes) and for major cardiovascular events. In men, it was statistically significant for all categories of events (total and specific mortality, all coronary events, all strokes, and major cardiovascular events). The odds ratios for any category of event did not differ significantly between men and women. In absolute terms, the benefit in women was seen primarily for strokes; in men, treatment prevented as many coronary events as strokes. Graphical analyses suggest that these results could be completely explained by the difference in untreated risk. CONCLUSIONS: In terms of relative risk, treatment benefit did not differ between women and men. The absolute risk reduction attributable to treatment seemed to depend on untreated risk. These findings underline the need to predict accurately the untreated cardiovascular risk of an individual person in order to rationalize and individualize antihypertensive treatment.

Adrenergic beta-Antagonists↗
PubMed1997

Effect of antihypertensive treatment in patients having already suffered from stroke. Gathering the evidence. The INDANA (INdividual Data ANalysis of Antihypertensive intervention trials) Project Collaborators.

BACKGROUND AND PURPOSE: Drug treatment of high blood pressure has been shown to reduce the associated cardiovascular risk. Stroke represents the type of event more strongly linked with high blood pressure, responsible for a high rate of death or invalidity, and with the highest proportion of events that can be avoided by treatment. Hypertensive patients with a history of cerebrovascular accident are at particularly high risk of recurrence. Specific trials of blood pressure lowering drugs in stroke survivors showed inconclusive results in the past. METHODS: We performed a meta-analysis using all available randomized controlled clinical trials assessing the effect of blood pressure lowering drugs on clinical outcomes (recurrence of stroke, coronary events, cause-specific, and overall mortality) in patients with prior stroke or transient ischemic attack. RESULTS: We identified 9 trials, including a total of 6752 patients: 2 trials included 551 hypertensive stroke survivors; 6 trials of hypertensive patients included a small proportion of stroke survivors (536 patients); 1 trial included stroke survivors, whether hypertensive or not (5665 patients). The recurrence of stroke, fatal and nonfatal, was significantly reduced in active groups compared with control groups consistently across the different sources of data (relative risk of 0.72, 95% confidence interval: 0.61 to 0.85). There was no evidence that this intervention induced serious adverse effect. CONCLUSIONS: Blood pressure lowering drug interventions reduced the risk of stroke recurrence in stroke survivors. Available data did not allow to verify whether such benefit depends on initial blood pressure level. More data are needed before considering antihypertensive therapy in normotensive patients at high cerebrovascular risk.

Aged↗
PubMed1993

Meta-analysis.

Explore the source record for details and available documents.

Data Display↗
PubMed1982

Natural history of breast cancer.

Retrospective analysis was made of 3,918 cases of breast cancer seen during 1954-1964. Median survival was 4.5 years and 30% of patients survived through a 10-year period. For stages I, II, and III patients, the mortality increased during 1-4 years after diagnosis and then slowly declined. Beyond 15 years, stage III patients assumed the same mortality (5%) as those with lesser disease; 58% excess of deaths from all causes after 15-20 years showed that breast cancer was not curable within 20 years but ultimately, taking account of clinical status, 51% of 5-year survivors with stages I-III disease are cured.

Breast Neoplasms↗
PubMed1980

Late results of the Royal Free Hospital prospective controlled trial of prednisolone therapy in hepatitis B surface antigen negative chronic active hepatitis.

A long-term follow-up of at least 10 years or until death of 44 patients taking part in a controlled prospective trial of prednisolone therapy in hepatitis B antigen negative chronic active hepatitis (lupoid hepatitis) has been performed at the Royal Free Hospital, London. Patients presenting between 1963 and 1967 were randomly allocated into control and treatment groups. Ten year life table survival curves showed a significantly improved survival in the treatment group where 63% of patients were alive at 10 years compared with only 27% in the control group (log rank test, P = 0.03). The median survival in the treatment group was 12.2 years compared with 3.3 years in the control group. The mean duration of treatment was 4.5 years. Age, presence of antinuclear factor, cirrhosis, or level of serum transaminases at presentation did not appear to affect survival. Male patients if untreated had a poorer prognosis than females (P = 0.02). The natural history of chronic active hepatitis appeared from clinical, biochemical, and histological findings to be from an active hepatitis or cirrhosis to inactive macronodular cirrhosis. Prednisolone therapy significantly improved survival by reducing mortality in the early active phase of the disease.

Adolescent↗
PubMed1979

Measuring the effect of a mobile coronary care unit upon the community.

A mobile coronary care unit working within a geographically defined area retrieved 20% of the estimated number of cases with myocardial infarction. These cases were similar to the population at risk in terms of age, sex, and previous history of ischaemic heart disease. Patients retrieved by the mobile unit had a lower overall case fatality ratio. This discrepancy was greater than could be explained by resuscitation or preventive treatment by the mobile unit teams. Reasons for this difference in mortality were explored. The benefits of the mobile coronary care unit were obvious in terms of the existing service but small in terms of the community. Any judgment on the effectiveness of a mobile unit must use both approaches to get a balanced view.

Adult↗
PubMed1976

Comparison of intensive versus moderate chemotherapy of lymphocytic lymphomas: a progress report.

In an Easter Cooperative Oncology Group trial, Cytoxan-prednisone (CP) Induction was compared to BCNU-prednisone (BP) in 273 patients with lymphocytic lymphoma. Response rates were comparable, with 21% achieving complete response and 40%, partial response. Patients with a nodular pattern responded better. Maintenance phase comparing cyclic intensive therapy (BCVP) with intermittent chlorambucil revealed the superiority of BCVP as demonstrated by improvement of the quality of response and somewhat longer remissions. The value of the Rappaport classification in the evaluation of lymphoma chemotherapy results is discussed. It is suggested tha NHL be separated into "favorable" and "unfavorable" groups, based on the presence or absence of nodularity and treatment schedules devised accordingly.

Adult↗
PubMed1976

A method to measure the adsorption of bile salts to vegetable fiber of differing water holding capacity.

Dietary vegetable fibers have physico-chemical properties which may influence their role in nutrition. A method is described which measures bile acid adsorption to fibers of differing water holding capacity. Such absorption studies are complicated by the water held in the fiber matrix which includes bile acid in solution. The entrapped solution gives some apparent adsorption but this can be removed by washing the fibers with water. This method differentiates between strong adsorption and reversible adsorption. This enables dietary vegetable fibers to be classified according to their bile acid absorption capacity which may be useful in selecting fibers for clinical trials.

Adsorption↗
PubMed1975

Comparative evaluation of combined radiation-chlorambucil treatment of ovarian carcinomatosis.

In a study conducted by the Eastern Cooperative Oncology Group, 51 evaluable women with advanced ovarian carcinoma were randomized to either abdominal radiation therapy alone, chlorambucil alone, or to a combination of radiation therapy and chlorambucil by members of the Eastern Cooperative Oncology Group. Provision was made for crossover therapy for patients who were nonresponders to a single modality of treatment. Parameters followed included objective and subjective response rates and patient survival. The total response rate was 51%, with no significant difference among the three treatment regimens. Regarding survival, radiation therapy alone was significantly superior to the other regimens, with an average survival of 94.9 weeks. Best results were obtained in patients with normal performance status; for this group, radiation therapy alone offered the best chance for prolonged survival.

Chlorambucil↗
PubMedDate not supplied

INDANA: a meta-analysis on individual patient data in hypertension. Protocol and preliminary results.

The overall effect of antihypertensive drug treatment has been well documented. The proportion of patients who benefit varies according to their baseline cardiovascular risk, and is small for the majority of people treated. Some investigators propose limiting the treatment target population to patients at high cardiovascular risk, but several assumptions must be made to justify this procedure. The INDANA project is a meta-analysis based on individual patient data, and thus offers the opportunity to check the validity of these assumptions. Its main objective is to identify responders (and non-responders) in the drug treatment of hypertension. The rationale and methods for such an approach are presented here, with the solution for some technical problems. The conclusion of the data collection has shown that the project is feasible. The results of the main analysis should be available in 1996, and should contribute to the selection of responders and to the individualization of the treatment of hypertension.

Humans↗