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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)
OBJECTIVE To investigate change in mental health after smoking cessation compared with continuing to smoke. DESIGN Systematic review and meta-analysis of observational studies. DATA SOURCES Web of Science, Cochrane Central Register of Controlled Trials, Medline, Embase, and PsycINFO for relevant studies from inception to April 2012. Reference lists of(More)
OBJECTIVE To assess the validity of case mix adjustment methods used to derive standardised mortality ratios for hospitals, by examining the consistency of relations between risk factors and mortality across hospitals. DESIGN Retrospective analysis of routinely collected hospital data comparing observed deaths with deaths predicted by the Dr Foster Unit(More)
OBJECTIVE To independently evaluate the impact of the second phase of the Health Foundation's Safer Patients Initiative (SPI2) on a range of patient safety measures. Design A controlled before and after design. Five substudies: survey of staff attitudes; review of case notes from high risk (respiratory) patients in medical wards; review of case notes from(More)
OBJECTIVES To conduct an independent evaluation of the first phase of the Health Foundation's Safer Patients Initiative (SPI), and to identify the net additional effect of SPI and any differences in changes in participating and non-participating NHS hospitals. DESIGN Mixed method evaluation involving five substudies, before and after design. SETTING NHS(More)
Stepped-wedge cluster randomised trials (SW-CRTs) are being used with increasing frequency in health service evaluation. Conventionally, these studies are cross-sectional in design with equally spaced steps, with an equal number of clusters randomised at each step and data collected at each and every step. Here we introduce several variations on this design(More)
BACKGROUND AND OBJECTIVE Utilities (values representing preferences) for healthcare priority setting are typically obtained indirectly by asking patients to fill in a quality of life questionnaire and then converting the results to a utility using population values. We compared such utilities with those obtained directly from patients or the public. (More)
The frequency of visits to Emergency Departments (ED) varies greatly between populations. This may reflect variation in patient behaviour, need, accessibility, and service configuration as well as the complex interactions between these factors. This study investigates the relationship between distance, socio-economic deprivation, and proximity to an(More)
BACKGROUND To examine the effects of physical activity on the development and progression of microvascular complications in patients with type 1 diabetes. METHODS A retrospective analysis of data from the Diabetes Control and Complications trial was undertaken. Physical activity data was collected at baseline for each of 1441 recruits, converted to(More)