Objectives To assess aspects of the internal validity of recently published cluster randomised trials and explore the reporting of information useful in assessing the external validity of these trials. Data extraction To assess aspects of internal validity we extracted data on appropriateness of sample size calculations and analyses, methods of identifying and recruiting individual participants, and blinding. To explore reporting of information useful in assessing external validity we extracted data on cluster eligibility, cluster inclusion and retention, cluster generalisability, and the feasibility and acceptability of the intervention to health providers in clusters. Results 21 (62%) trials accounted for clustering in sample size calculations and 30 (88%) in the analysis; about a quarter were potentially biased because of procedures surrounding recruitment and identification of patients; individual participants were blind to allocation status in 19 (56%) and outcome assessors were blind in 15 (44%). In almost half the reports, information relating to generalisability of clusters was poorly reported, and in two fifths there was no information about the feasibility and acceptability of the intervention. Conclusions Cluster randomised trials are essential for evaluating certain types of interventions. Issues affecting their internal validity, such as appropriate sample size calculations and analysis, have been widely disseminated and are now better addressed by researchers. Blinding of those identifying and recruiting patients to allocation status is recommended but is not always carried out. There may be fewer barriers to internal validity in trials in which individual participants are not recruited. External validity seems poorly addressed in many trials, yet is arguably as important as internal validity in judging quality as a basis for healthcare intervention. INTRODUCTIONIn cluster randomised trials, groups or clusters of individuals, rather than individuals themselves, are randomised. These trials are increasingly common in health services research, being particularly appropriate for evaluating interventions aimed at changing behaviour in patients or practitioners or changing organisation of services. Clusters might, for example, consist of patients in general practices or older people in nursing homes. Cluster randomised trials are pragmatic, measuring effectiveness rather than efficacy 1 and should therefore be both internally and externally valid.

2 0 0 8 ) Journal of Clinical Nursing 17, 519-530Midwives' views of the importance of genetics and their confidence with genetic activities in clinical practice: implications for the delivery of genetics education Aims and objectives. The aim of the study was to ascertain the level of importance midwives attach to integrating genetics into midwifery care and to compare that with their self-reported level of confidence in incorporating genetics into their clinical practice. Background. Previous work has shown that many midwives feel ill-prepared for the increased integration of genetics into clinical practice and often only limited genetics education provision is in place. With the application of genetics to midwifery practice increasing, it is important that midwives develop their knowledge and skills to meet this growing clinical role. This study was therefore developed to ascertain the attitudes and educational needs of midwives by exploring genetic issues likely to arise in clinical practice and the confidence individuals felt in dealing with them. Design. A survey questionnaire with open and closed questions. Methods. All midwives working in four National Health Service trusts (n ¼ 817) were invited to self-complete the validated questionnaire anonymously. Data were collected on demographics and preferred continued professional development options for future educational programme development. Likert scales were used to rate the importance of genetic activities and midwives' confidence to perform them based on the genetic activities which were first listed and then presented embedded within specific clinical scenarios. Results. The response rate was 51% (n ¼ 416). The majority of midwives felt that genetics was important but many did not feel confident about integrating it into their clinical practice. Across all scenarios >60% of midwives were not confident on any risk identification or risk communication activities. The majority of midwives were receptive to genetics education particularly if delivered from a clinical rather than a psychosocial or scientific perspective. Conclusion. This study demonstrates the need for midwives' pre-and postregistration education to include clinically relevant genetics. The evidence presented here can inform the design, development and delivery of future educational initiatives. What this study adds. This study was the first to identify the educational needs of midwives related to integrating genetics into midwifery clinical practice. It provides evidence of key topics to be included in educational programmes: referring to specialist genetics services, genetic testing, risk and communicating genetic information. It shows the type and format of course preferred by clinically based midwives: interactive workshops and lectures using clinical patient-based case examples will attract midwives to participate and will be better received by their managers. Relevance to clinical practice. Midwives view genetics as important in their clinical practice. However, they have little confid...

Background-The basis for progressive attenuation of the effects of organic nitrates during long-term therapy (nitrate tolerance) remains controversial; proposed mechanisms include impaired nitrate bioconversion resulting in decreased release of nitric oxide (NO) from nitrates and/or increased NO clearance through a reaction with incrementally generated superoxide (O 2 -). Methods and Results-Patients undergoing elective coronary artery bypass were randomized to receive 24 hours of intravenously infused nitroglycerin (NTG; nitrate group) or no nitrate therapy (control group). Discarded segments of the internal mammary artery and saphenous vein were used to examine (1) vascular responsiveness to NTG, sodium nitroprusside, and the calcium ionophore A23187; (2) bioconversion of NTG to 1,2-and 1,3-glyceryl dinitrate; and (3) the generation of O 2 -. Responses to NTG were reduced 3-to 5-fold in vessels from the nitrate group compared with control vessels (PϽ0.01 for both types of segments), whereas responses to sodium nitroprusside and A23187 were unchanged. Tissue content of 1,2-glyceryl dinitrate was lower (Pϭ0.012) in the saphenous veins from the nitrate group than in those from the control group. O 2 -generation was greater (PϽ0.01) in internal mammary artery samples from the nitrate group than in those from the control group. However, incremental O 2 -generation induced by an inhibitor of superoxide dismutase did not affect NTG responses. Conclusions-NTG tolerance in patients with coronary artery disease is nitrate-specific and is associated with evidence of impaired NTG bioconversion. Tolerance was associated with incremental O 2 -generation, but short-term elevation of O 2