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Biomedical subjects

I Chalmers

Publications and source records attributed to I Chalmers.

At least 73 records · Page 4Linked to original sources
PubMed1993

Preparing and updating systematic reviews of randomized controlled trials of health care.

People providing health care tend to turn to review articles rather than reports of primary research when seeking information to guide their practices. For this reason, the process of reviewing the results of primary research must respect scientific principles. Reviews must be kept up to date and disseminated in appropriate ways to the people who make decisions about health care, including policy makers, practitioners, and users of the health services. This article describes the methods developed and used in an attempt to address these challenges for care during pregnancy and childbirth.

Databases, Bibliographic↗
PubMed1992

A review of prospectively controlled comparisons of epidural with non-epidural forms of pain relief during labour.

OBJECTIVE: To assess the extent to which hypotheses about potential adverse effects of epidural analgesia during labour can be tested using evidence from controlled comparisons of epidural with non-epidural forms of pain relief. INCLUSION CRITERIA: Prospective studies in which an attempt had been made to use random allocation to generate comparable groups of women receiving epidural and non-epidural forms of pain relief during labour. IDENTIFICATION OF RELEVANT STUDIES: Systematic hand search of a total of 36 anaesthetic, obstetric and general journals, and more than 30 other journals (1950-1990), and a search of MEDLINE (1966-1990). DATA COLLECTION: Data were abstracted from published reports of 9 controlled trials, involving a total of 600 women. It was possible to obtain some missing information and data from the investigators. RESULTS: Very few postulated effects of epidural block during labour can be confirmed or rejected on the basis of the evidence generated by the small number of controlled trials. Evidence derived from these trials confirms that epidural block provides more effective relief of pain than alternatives; and that if it is continued during the second stage of labour, it can cause a substantial increase in the use of instrumental delivery. CONCLUSIONS: Considering the very widespread use of epidural block during labour, remarkably little is known about its short-term and long-term effects. In view of hypotheses about potentially important adverse effects, there is still a need to conduct larger, better designed randomised controlled trials.

Journal Article↗
PubMed1991

The work of the National Perinatal Epidemiology Unit. One example of technology assessment in perinatal care.

This article describes one approach to assessing the effects of perinatal care--that adopted by the National Perinatal Epidemiology Unit in Oxford, England. The unit's research has been based primarily on a combination of simple, descriptive analyses of observational data and statistically robust analyses of evidence derived from randomized controlled trials.

Diffusion of Innovation↗
PubMed1991

Cost implications of different approaches to the prevention of respiratory distress syndrome.

Because the incidence of both neonatal respiratory distress syndrome and neonatal mortality can be reduced by giving corticosteroids to women expected to deliver preterm and by giving surfactant to babies at high risk of developing hyaline membrane disease, we have considered what effects the adoption of one or both of these preventive policies would have on the costs of neonatal care. We have estimated the effects of treatment from overviews of the relevant controlled trials, and estimated costs from observations of care at one neonatal unit. Our results suggest that if either of these policies is adopted for all babies under 35 weeks' gestation at a drug cost of 150 pounds or less/baby, the overall costs of care would be reduced by between 1 and 10%. The cost per survivor would be reduced by up to 16% even if the drug cost were to be as high as pounds 550/baby. If the policies were to be adopted only for babies under 31 weeks' gestation, both policies would result in a reduction in cost of between 5 and 16%/survivor, although the increased survival resulting from the policies would lead to an increase in overall costs for babies of less then 31 weeks' gestation of between 7 and 32%.

Adrenal Cortex Hormones↗
PubMed1990

A cohort study of summary reports of controlled trials.

Substantial numbers of clinical trials continue to be reported only in summary reports that present insufficient methodological details to permit informed judgments about the likely validity of the conclusions. Using a cohort of 176 controlled trials reported in summary form, we tested the hypotheses that they would be more likely to be followed by full reports if, on the basis of the information provided in the summary report, (1) the trial was judged to be methodologically sound, (2) the results favored the test treatment, and (3) the sample size was relatively large. The results of univariate and multivariate analyses provided support for only the third of these hypotheses. Investigators, as well as those who fund and sanction the conduct of clinical research, should make greater efforts to ensure that clinical trials are reported properly.

Clinical Trials as Topic↗
PubMed1990

Underreporting research is scientific misconduct.

Substantial numbers of clinical trials are never reported in print, and among those that are, many are not reported in sufficient detail to enable judgments to be made about the validity of their results. Failure to publish an adequate account of a well-designed clinical trial is a form of scientific misconduct that can lead those caring for patients to make inappropriate treatment decisions. Investigators, research ethics committees, funding bodies, and scientific editors all have responsibilities to reduce underreporting of clinical trials. An extended use of prospective registration of trials at inception, as well as benefiting clinical research in other ways, could help people to play their respective roles in reducing underreporting of clinical trials.

Biomedical Research↗
PubMed1990

The effects of corticosteroid administration before preterm delivery: an overview of the evidence from controlled trials.

Continuing differences of opinion among obstetricians and neonatologists about the place of corticosteroid administration before preterm delivery have prompted us to carry out a systematic review of the relevant controlled trials, using methods designed to minimize systematic and random error. Data from 12 controlled trials, involving over 3000 participants, show that corticosteroids reduce the occurrence of respiratory distress syndrome overall and in all the subgroups of trial participants that we examined. This reduction in respiratory morbidity was associated with reductions in the risk of intraventricular haemorrhage, necrotizing enterocolitis and neonatal death. There is no strong evidence suggesting adverse effects of corticosteroids. The risks of fetal and neonatal infection may be raised if they are administered after prolonged rupture of the membranes, but this possibility is not substantiated by the results of the available trials. The available data on long-term follow-up suggest that the short-term beneficial effects of corticosteroids may be reflected in reduced neurological morbidity in the longer term.

Adrenal Cortex Hormones↗
PubMed1989

Reducing the incidence of infection after caesarean section: implications of prophylaxis with antibiotics for hospital resources.

OBJECTIVES: To estimate the cost effectiveness of giving prophylactic antibiotics routinely to reduce the incidence of wound infection after caesarean section. DESIGN: Estimation of cost effectiveness was based, firstly, on a retrospective overview of 58 controlled trials and, secondly, on evidence about costs derived from data and observations of practice. SETTING: Trials included in the overview were from obstetric units in several different countries, including the United Kingdom. The costing study was based on data referring to the John Radcliffe Maternity Hospital, Oxford. SUBJECTS: A total of 7777 women were included in the 58 controlled trials comparing the effects of giving routine prophylactic antibiotics at caesarean section with either treatment with a placebo or no treatment. Cost estimates were based on data on 486 women who had caesarean sections between January and September 1987. MAIN OUTCOME MEASURE: Cost effectiveness of prophylaxis with antibiotics. RESULTS: The odds of wound infection are likely to be reduced by between about 50 and 70% by giving antibiotics routinely at caesarean section. Forty one (8.4%) women who had caesarean section were coded by the Oxford obstetric data system as having developed wound infection. The additional average cost of hospital postnatal care for women with wound infection (compared with women who had had caesarean section and no wound infection) was estimated to be 716 pounds; introducing routine prophylaxis with antibiotics would reduce average costs of postnatal care by between 1300 pounds and 3900/100 pounds caesarean sections (at 1988 prices), depending on the cost of the antibiotic used and its effectiveness. CONCLUSIONS: The results suggest that giving antibiotics routinely at caesarean section will not only reduce rates of infection after caesarean section but also reduce costs.

Ampicillin↗