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Surgery and other invasive therapies are complex interventions, the assessment of which is challenged by factors that depend on operator, team, and setting, such as learning curves, quality variations, and perception of equipoise. We propose recommendations for the assessment of surgery based on a five-stage description of the surgical development process.(More)
BACKGROUND A possible therapeutic effect of diagnostic tubal patency testing has been debated in the literature for half a century. Further debate surrounds whether oil-soluble or water-soluble contrast media might have the bigger fertility-enhancing effect. OBJECTIVES To evaluate the effect of flushing a woman's fallopian tubes with oil- or water-soluble(More)
OBJECTIVE To compare the effects of laparoscopic hysterectomy and abdominal hysterectomy in the abdominal trial, and laparoscopic hysterectomy and vaginal hysterectomy in the vaginal trial. DESIGN Two parallel, multicentre, randomised trials. SETTING 28 UK centres and two South African centres. PARTICIPANTS 1380 women were recruited; 1346 had surgery;(More)
BACKGROUND Stepped wedge randomised trial designs involve sequential roll-out of an intervention to participants (individuals or clusters) over a number of time periods. By the end of the study, all participants will have received the intervention, although the order in which participants receive the intervention is determined at random. The design is(More)
This is the second in a four-part series of articles detailing the epistemology of patient safety research. This article concentrates on issues of study design. It first considers the range of designs that may be used in the evaluation of patient safety interventions, highlighting the circumstances in which each is appropriate. The paper then provides(More)
Previously the diagnosis of sex and cystic fibrosis status has been studied on single cells using the polymerase chain reaction (PCR). It has been suggested that allelic drop-out (PCR failure of one allele) and/or preferential amplification (hypo-amplification of one allele) may contribute to poor reliability and misdiagnosis, although this remains(More)
BACKGROUND Cluster randomised controlled trials (CRCTs) are frequently used in health service evaluation. Assuming an average cluster size, required sample sizes are readily computed for both binary and continuous outcomes, by estimating a design effect or inflation factor. However, where the number of clusters are fixed in advance, but where it is possible(More)
Surgical innovation is an important part of surgical practice. Its assessment is complex because of idiosyncrasies related to surgical practice, but necessary so that introduction and adoption of surgical innovations can derive from evidence-based principles rather than trial and error. A regulatory framework is also desirable to protect patients against(More)
The history of monitoring the outcomes of health care by external agencies can be traced to ancient times. However, the danger, now as then, is that in the search for improvement, comparative measures of mortality and morbidity are often overinterpreted, resulting in judgments about the underlying quality of care. Such judgments can translate into(More)
Currently, clinical trials tend to be individually funded and applicants must include a power calculation in their grant request. However, conventional levels of statistical precision are unlikely to be obtainable prospectively if the trial is required to evaluate treatment of a rare disease. This means that clinicians treating such diseases remain in(More)