Bradykinin and cysteinyl leukotriene concentrations in cell-salvaged blood before and after passage through negatively charged filters during clinical use in cancer patients: a pilot study.

It has been suggested that giving cell-salvaged blood through a leucocyte depletion filter can cause hypotension due to bradykinin released when factor XII and platelets are activated by the negatively charged surface of the filter. We measured the concentration of bradykinin and cysteinyl leukotrienes in cell-salvaged blood sampled before and after passage through a negatively charged leucodepletion filter in 24 consecutive patients with gynaecological or bowel cancer undergoing elective surgery with cell salvage. In no case was an increase in bradykinin concentration observed after passage through the filter; in 23 patients the post-filtration bradykinin concentration was zero (p = 0.007). The change in the concentration of cysteinyl leukotrienes detected during passage across the filter was not statistically significant (p = 0.1). Our findings do not support the suggestion that either bradykinin or cysteinyl leukotrienes are generated in cell-salvaged blood during passage through leucodepletion filters.

Estimating the marginal value of 'better' research output: 'designed' versus 'routine' data in randomised controlled trials.

We recently completed a study which demonstrated that the costs of health technology assessment (HTA) by randomised controlled trial (RCT) can be reduced by substituting routine datasets for data designed and collected specifically for a trial. This cost reduction, however, had the effect of reducing the quality of the research output. In the present study we attempted to tease out the values attached to the 'better' information provided by designed data RCTs using a mock grants committee. Two valuation techniques, implied values and willingness to pay, were used. Ex ante valuations were determined by comparing alternative research proposals - a more costly version using designed data and a cheaper version using routine data. Ex post valuations were determined by comparing results of both versions. The exercise was performed on four exemplar studies. Overall, the committee expressed a general lack of trust towards routine data both ex ante and ex post and placed high values on the better information from the designed data studies - particularly information on preferences. This suggests that currently available routine datasets are not perceived to be able to provide efficient alternatives to designed data for RCTs.

Can randomised trials rely on existing electronic data? A feasibility study to explore the value of routine data in health technology assessment.

OBJECTIVES: To estimate the feasibility, utility and resource implications of electronically captured routine data for health technology assessment by randomised controlled trials (RCTs), and to recommend how routinely collected data could be made more effective for this purpose. DATA SOURCES: Four health technology assessments that involved patients under care at five district general hospitals in the UK using four conditions from distinct classical specialties: inflammatory bowel disease, obstructive sleep apnoea, female urinary incontinence, and total knee replacement. Patient-identifiable, electronically stored routine data were sought from the administration and clinical database to provide the routine data. REVIEW METHODS: Four RCTs were replicated using routine data in place of the data already collected for the specific purpose of the assessments. This was done by modelling the research process from conception to final writing up and substituting routine for designed data activities at appropriate points. This allowed a direct comparison to be made of the costs and outcomes of the two approaches to health technology assessment. The trial designs were a two-centre randomised trial of outpatient follow-up; a single-centre randomised trial of two investigation techniques; a three-centre randomised trial of two surgical operations; and a single-centre randomised trial of perioperative anaesthetic intervention. RESULTS: Generally two-thirds of the research questions posed by health technology assessment through RCTs could be answered using routinely collected data. Where these questions required analysis of NHS resource use, data could usually be identified. Clinical effectiveness could also be judged, using proxy measures for quality of life, provided clinical symptoms and signs were collected in sufficient detail. Patient and professional preferences could not be identified from routine data but could be collected routinely by adapting existing instruments. Routine data were found potentially to be cheaper to extract and analyse than designed data, and they also facilitate recruitment as well as have the potential to identify patient outcomes captured in remote systems that may be missed in designed data collection. The study confirmed previous evidence that the validity of routinely collected data is suspect, particularly in systems that are not under clinical and professional control. Potential difficulties were also found in identifying, accessing and extracting data, as well as in the lack of uniformity in data structures, coding systems and definitions. CONCLUSIONS: Routine data have the potential to support health technology assessment by RCTs. The cost of data collection and analysis is likely to fall, although further work is required to improve the validity of routine data, particularly in central returns. Better knowledge of the capability of local systems and access to the data held on them is also essential. Routinely captured clinical data have real potential to measure patient outcomes, particularly if the detail and precision of the data could be improved.

A systematic review of comparisons of effect sizes derived from randomised and non-randomised studies.

BACKGROUND: There is controversy about the value of evidence about the effectiveness of healthcare interventions from non-randomised study designs. Advocates for quasi-experimental and observational (QEO) studies argue that evidence from randomised controlled trials (RCTs) is often difficult or impossible to obtain, or is inadequate to answer the question of interest. Advocates for RCTs point out that QEO studies are more susceptible to bias and refer to published comparisons that suggest QEO estimates tend to find a greater benefit than RCT estimates. However, comparisons from the literature are often cited selectively, may be unsystematic and may have failed to distinguish between different explanations for any discrepancies observed. OBJECTIVES: The aim was to investigate the association between methodological quality and the magnitude of estimates of effectiveness by comparing systematically estimates of effectiveness derived from RCTs and QEO studies. Quantifying any such association should help healthcare decision-makers to judge the strength of evidence from non-randomised studies. Two strategies were used to minimise the influence of differences in external validity between RCTs and QEO studies: a comparison of the RCT and QEO study estimates of effectiveness of any intervention, where both estimates were reported in a single paper a comparison of the RCT and QEO study estimates of effectiveness for specified interventions, where the estimates were reported in different papers. The authors also sought to identify study designs that have been proposed to address one or more of the problems often found with conventional RCTs. DATA SOURCES: Relevant literature was identified from: The Cochrane Library, MEDLINE, EMBASE, DARE, and the Science Citation Index. References of relevant papers already identified experts. Electronic searches were very difficult to design and yielded few papers for the first strategy and when identifying study designs. CHOICE OF INTERVENTIONS TO REVIEW FOR STRATEGIES 1 AND 2: For strategy 1, any intervention was eligible. For strategy 2, interventions for which the population, intervention and outcome investigated were anticipated to be homogeneous across studies were selected for review: Mammographic screening (MSBC) of women to reduce mortality from breast cancer. Folic acid supplementation (FAS) to prevent neural tube defects in women trying to conceive. DATA EXTRACTION AND QUALITY ASSESSMENT: Data were extracted by the first author and checked by the second author. Disagreements were negotiated with reference to the paper concerned. For strategy 1, study quality was scored using a checklist to assess whether the RCT and QEO study estimates were derived from the same populations, whether the assessment of outcomes was 'blinded', and the extent to which the QEO study estimate took account of possible confounding. For strategy 2, a more detailed instrument was used to assess study quality on four dimensions: the quality of reporting, the generalisability of the results, and the extent to which estimates of effectiveness may have been subject to bias or confounding. All quality assessments were carried out by three people. DATA SYNTHESIS AND ANALYSIS: For strategy 1, pairs of comparisons between RCT and QEO study estimates were classified as high or low quality. Seven indices of the size of discrepancies between estimates of effect size and outcome frequency were calculated, where possible, for each comparison. Distributions of the size and direction of discrepancies were compared for high- and low-quality comparisons. FOR STRATEGY 2, THREE ANALYSES WERE CARRIED OUT: Attributes of the instrument were described by k statistics, percentage agreement, and Cronbach's a values. Regression analyses were used to investigate -variations in study quality. (ABSTRACT TRUNCATED)

Integrated care for asthma: matching care to the patient.

The purpose of the present study was to investigate whether criteria associated with assignment of asthma patients between general practice (GP) care alone, integrated care (shared between GP care and hospital clinic) or conventional specialist review could be identified, and whether outcomes for these patients differed over the next 12 months. Seven hundred and sixty four patients with a diagnosis of asthma and previously assigned to either integrated care or clinic care were reviewed after 1 year and reassigned. These patients were then followed for another 12 months and clinical data were collected over this time. After 12 months in clinic care or integrated care, assignment to integrated care was predicted by previous participation in integrated care (OR 2.94), patient preference for integrated care (OR 3.7), no admission (OR 1.56), fewer steroid courses during the previous year (OR 0.88) and nonattendance at review (OR 0.43) in the previous 12 months. Patient discharge to GP care was predicted by higher level of forced expiratory volume in one second (FEV1) (OR 1.49), lower number of GP consultations for troublesome asthma (OR 0.78), and nonattendance for review in the preceding year (OR 2.15). In the following 12 months, the three groups of patients differed significantly in hospital admissions (Discharged = 0.008; Integrated = 0.12; Clinic = 0.31), bronchodilators prescribed (Discharged = 8.5; Integrated = 10.2; Clinic = 13.9), GP consultations (Discharged = 1.3; Integrated = 3.0; Clinic = 4.1) and oral steroid courses (Discharged = 0.62; Integrated = 1.7; Clinic = 2.4). Patients assigned to integrated care, clinic care or discharged to general practice care form three distinct patient populations differing retrospectively and prospectively in morbidity and admission risk. In particular, patients assigned to integrated care fall midway in risk and morbidity between those discharged or those retained in clinic care. These results suggest that integrated care provides general practitioners with a system of management for asthma patients, for whom they do not wish frequent specialist review but who they do not believe can safely be discharged to general practice care only.