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I Chalmers

Publications and source records attributed to I Chalmers.

At least 19 recordsLinked to original sources
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↗
PubMed1989

Retrospective and prospective identification of unpublished controlled trials: lessons from a survey of obstetricians and pediatricians.

Investigations in which statistically significant differences between treatment groups have not been observed are less likely than others to be reported in scientific journals. In clinical research, this selective suppression of "negative" results may lead to the adoption of ineffective or hazardous treatments. In an attempt to obtain information about unpublished trials in perinatal medicine, letters were sent to 42,000 obstetricians and pediatricians in 18 countries. As a result, we were notified of 395 unpublished randomized trials. Only 18 of the trials had been completed more than 2 years before the survey, a period during which at least 2300 reports of perinatal trials had been published. Of the 395 unpublished trials, 125 had ceased recruitment within the 2 years prior to the survey, 193 were actively recruiting at the time of the survey, and 59 were about to begin recruitment. It was concluded that publication bias will not be addressed successfully by attempts to obtain information about unpublished trials retrospectively. However, since the response rate to our request for details about ongoing and planned trials was good, prospective registration of trials at inception appears to be a feasible approach to reducing publication bias and its adverse consequences. An additional merit of prospective registration of clinical trials is that it should reduce unnecessary duplication (as opposed to necessary replication) in research and promote more effective collaboration.

Clinical Trials as Topic↗