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L A Stewart

Publications and source records attributed to L A Stewart.

At least 37 records · Page 2Linked to original sources
PubMed1995

Practical methodology of meta-analyses (overviews) using updated individual patient data. Cochrane Working Group.

Meta-analyses using updated individual patient data may provide the most reliable means of combining data from similar randomized controlled trials. The benefits of this approach to systematic reviews are described. Guidance, based on the experience of several groups who have undertaken such projects, is given. This includes practical advice on initiating and maintaining collaboration, the time and resources required to undertake these usually international projects and methods of data checking and validation. Example proforma are included.

Data Collection↗
PubMed1995

Adjuvant chemotherapy for soft-tissue sarcoma: review and meta-analysis of the published results of randomised clinical trials.

Fifteen published randomised trials comparing adjuvant chemotherapy with no chemotherapy in soft-tissue sarcoma (STS) were identified (1546 patients). A qualitative review and a meta-analysis of this published literature were performed. With the qualitative review it was not possible to synthesise the apparently conflicting results of individual trials. The meta-analysis of the published data suggests an improvement in survival at 2 years (OR = 0.73, 95% CI = 0.53-0.99, P = 0.044) and at 5 years (OR = 0.59, 95% CI = 0.45-0.78, P = 0.0002) in favour of chemotherapy. However, the assumptions and approximations required to conduct this quantitative summary demand that the results are interpreted with caution. The only reliable means of assessing the current evidence on whether adjuvant chemotherapy has a role in the treatment of patients with STS, is to collect, check and reanalyse individual patients data (IPD) from each trial centrally, and formally combine the results in a stratified time-to-event analysis. Such an IPD analysis is currently being undertaken by an international collaborative group.

Adult↗
PubMed1995

Systematic reviews of randomized controlled trials: the need for complete data.

If the relative effectiveness of different treatments that might be used in clinical practice is to be evaluated reliably, it is very important that the evaluation is carried out in an appropriate manner. This is especially true where the differences between treatments are expected to be moderate, and so easily obscured by the play of chance or systematic bias. Although such differences are often of considerable clinical importance, they can be difficult to assess and require a large amount of randomized evidence. This evidence can be obtained through prospective randomized controlled trials, meta-analysis of results from past randomized trials, or ideally a combination of the two, with prospective trials contributing to future meta-analyses. Whichever technique is adopted, all possible biases must be minimized through the collection of as much randomized evidence as possible. In meta-analyses, this is best achieved by ensuring that all relevant trials, and all randomized participants in these trials, are included in the analysis. The gold standard for this might be a meta-analysis of individual patient data, in which details for each participant in every trial are collected and analysed centrally. This approach requires considerable time and effort. However, it will add to the analyses that can be performed and will remove many of the problems associated with a reliance on published data alone and some of the problems that can arise from the use of aggregate data. This paper sets out some of the reasons for this and some of the techniques used for individual patient data-based meta-analysis.

Bias↗
PubMed1994

Obtaining data from randomised controlled trials: how much do we need for reliable and informative meta-analyses?

Many randomised controlled trials compare treatments that will produce only moderate differences in outcome, but these differences can be clinically important. However, they are difficult to assess reliably and require a large amount of randomised evidence. This can be achieved through large prospective randomised trials which will accrue future patients, the meta-analysis of results from randomised trials involving patients from the past, or--ideally--both. The techniques require that all possible biases are minimised, and in meta-analyses this can best be achieved by ensuring that all of the randomised evidence--both trials and participants in those trials--is included. The meta-analysis of individual patient data has been described as the gold standard for this approach. It will remove many of the problems associated with relying solely on published data and some of the problems arising from a reliance on aggregate data, and will also add to the analyses that can be performed. Such projects, however, require considerable time and effort.

Bias↗
PubMed1993

Meta-analysis of the literature or of individual patient data: is there a difference?

The use of meta-analyses or overviews to combine formally the results of related randomised clinical trials is becoming increasingly common. However the distinction between analyses based on information extracted from the published literature and those based on collecting and reanalysing updated individual patient data is not clear. We have investigated the difference between meta-analysis of the literature (MAL) and meta-analysis of individual patient data (MAP) by comparing the two approaches using randomised trials of cisplatin-based therapy in ovarian cancer. The MAL was based on 788 patients and the MAP on 1329 and estimated median follow-ups were 3.5 and 6.5 years, respectively. The MAL gave a result of greater statistical significance (p = 0.027 vs p = 0.30) and an estimate of absolute treatment effect three times as large as the MAP (7.5% vs 2.5%). Publication bias, patient exclusion, length of follow-up, and method of analysis all contributed to this observed difference. The results of a meta-analysis of the literature alone may be misleading. Whenever possible, a meta-analysis of updated individual patient data should be done because this provides the least biased and most reliable means of addressing questions that have not been satisfactorily resolved by individual clinical trials.

Antineoplastic Agents↗
PubMed1993

Profile of female firesetters. Implications for treatment.

We studied 28 female arsonists and 28 female controls admitted to Holloway Prison over four months to examine the psychological and situational antecedents to firesetting so that the behaviour could be targeted for treatment. Over 92% of the arson group had received a psychiatric diagnosis. Both groups had similarly high rates of early deprivation and abuse. None of the female arsonists had set a fire for financial gain. There was no evidence of sexual arousal being associated with firesetting; only two women described their firesetting in terms that suggest a level of compulsion--one of these was alcoholic, the other was diagnosed as severely personality disordered. Several behavioural and psychological antecedents to offending were identified which could be targeted for treatment: low self-esteem, depression, limited communication skills, and deficits in anger management. The relapse prevention model is suggested as a possible intervention for recidivistic arsonists.

Adult↗
PubMed1993

The results of a quantitative overview of chemotherapy in advanced ovarian cancer: what can we learn?

The results of a quantitative overview (meta-analysis) of randomised clinical trials, considering the roles of combination chemotherapy and platinum in advanced ovarian cancer are briefly reviewed. This overview collected individual patient data from 45 randomised trials, comprising information from over 8,000 women, but even with this large dataset, no firm conclusions could be reached. However, the results suggest that in terms of survival: i) immediate platinum-based therapy is better than a non-platinum regimen; ii) platinum in combination is better than single-agent platinum when used at the same dose, and iii) carboplatin and cisplatin are equally effective. These results led to the launch of two international randomised clinical trials in ovarian cancer, each of which plans to accrue 2,000 patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Essentials of occupational contact dermatitis.

Occupational skin disease constitutes a disproportionately large percentage of all occupational illnesses. It is beneficial for the nurse to have a clear understanding of the relationship between the worker and occupational contact dermatitis. This article describes background information, diagnostic testing, and preventive measures.

Adrenal Cortex Hormones↗
PubMed1991

Modification of sleep respiratory patterns by auditory stimulation: indications of a technique for preventing sudden infant death syndrome?

Sudden infant death syndrome (SIDS) has been associated with premorbid respiratory irregularities that may contribute to the subsequent occurrence of SIDS (e.g. by chronic hypoxia). Conventional apnea alarms will detect periods of extended apnea but not other chronic respiratory irregularities that could contribute to SIDS. The effect of a brief, quiet, repetitive auditory stimulus on the sleep respiratory behavior of infant dogs and pigs was assessed. Stimulus presentation was associated with an increase in the sleep respiration rate irrespective of the stimulus presentation rate being faster or slower than the baseline respiratory rate, and irrespective of the pattern of presentation being regular or random. These results suggest that apnea monitoring systems may be improved by an additional function in which less extreme respiratory irregularities initiate the time-limited presentation of a quiet, repetitive, auditory stimulus, aimed at normalizing the respiratory pattern. This function could enhance the preventative role of the alarm systems by reducing the development of pathology that may promote some instances of SIDS.

Acoustic Stimulation↗
PubMed1986

Chorionic villus sampling. Clinical experience in 50 diagnostic cases.

The results of 50 diagnostic chorionic villus samplings (CVS) are presented. In all but 2, the fetus was at risk of a chromosomal abnormality. Sampling was successful in 48 cases. One patient aborted 4 days after the procedure. Two patients had missed abortions diagnosed on ultrasound 44 and 56 days after CVS. Seven patients elected to have their pregnancies terminated. All samplings were undertaken with a specially designed cannula using realtime ultrasound guidance between 9 and 11 weeks of amenorrhoea. Endocervical swabs and blood for maternal serum alpha fetoprotein estimations before and after the procedure were routinely taken. All patients were notified of the results in 8 days or less except in 3 where long-term cultures were necessary. Six patients have delivered and 34 pregnancies are continuing satisfactorily.

Abortion, Missed↗
PubMed1986

Chorionic villus sampling: cytogenetic experience in preliminary investigations and in 50 diagnostic cases.

The results of preliminary cytogenetic investigations of chorionic villus sampling (CVS) and its diagnostic application in 50 cases are reported. Preliminary investigations included the effect of short delays between biopsy and processing, levels of mitotic activity related to variations in processing, the incidence of tetraploidy, correlation of the karyotype of the chorionic villi with that of the fetus, and the results of banding studies. A protocol was then designed for application to diagnostic CVS. The 50 diagnostic cases included 4 with male karyotypes which were terminated due to a family history of an X-linked disorder, 1 trisomy 21, 1 trisomy 18, the finding of 1 aberrant cell out of 50 in an otherwise normal analysis, a 45, XY, t (13;21) karyotype, 2 fragile X negative karyotypes and in one case the presence of mosaicism was detected in chorionic villi and subsequently not confirmed at amniocentesis. The karyotype on the chorionic villi was 46XY/47XY +3.

Adult↗