Composite outcomes, in which multiple end points are combined, are frequently used as primary outcome measures in randomized trials and are often associated with increased statistical efficiency. However, such measures may prove challenging for the interpretation of results. In this article, we examine the use of composite outcomes in major clinical trials, assess the arguments for and against them, and provide guidance on their application and reporting. To assess incidence and quality of reporting, we systematically reviewed the use of composite end points in clinical trials in An-

Minimisation works towards minimising the total imbalance across all factors, rather than any one factor. Assume the first 18 general practices had been randomised and are distributed as in the table. The next general practitioner has a low Jarman score, a high patient to practice nurse ratio "hours per week," and is a non-fundholder. The number of practices of this type in the intervention group is 12-that is, 4 + 5 + 3-and in the control group is 10-that is, 3 + 4 + 3. Hence, to minimise the imbalance (even if not to eliminate it) this 19th practice would be allocated to the control group.Minimisation is possible by hand but a computer program helps when there are many factors or more then two treatment groups. Planning to use minimisation is a good discipline for making trialists think about prognostic factors before a study starts and helps ensure adherence to the protocol as a trial progresses.Cluster randomised controlled trial of expert system based on the transtheoretical ("stages of change") model for smoking prevention and cessation in schools Paul Aveyard, K K Cheng, Joanne Almond, Emma Sherratt, Robert Lancashire, Terry Lawrence, Carl Griffin, Olga Evans AbstractObjectives To examine whether a year long programme based on the transtheoretical model of behaviour change, incorporating three sessions using an expert system computer program and three class lessons, could reduce the prevalence of teenage smoking. Design Cluster randomised trial comparing the intervention to a control group exposed only to health education as part of the English national curriculum. Setting 52 schools in the West Midlands region. Participants 8352 students in year 9 (age 13-14 years) at those schools. Main outcome measures Prevalence of teenage smoking 12 months after the start of the intervention. Results Of the 8352 students recruited, 7444 (89.1%) were followed up at 12 months. The intention to treat odds ratio for smoking in the intervention group relative to control was 1.08 (95% confidence interval 0.89 to 1.33). Sensitivity analysis for loss to follow up and adjustment for potential confounders did not alter these findings. Conclusions The smoking prevention and cessation intervention based on the transtheoretical model, as delivered in this trial, is ineffective in schoolchildren aged 13-14.

BackgroundAccumulation of lifestyle physical activity is a current aim of health promotion, with increased stair climbing one public health target. While the workplace provides an opportunity for regular stair climbing, evidence for effectiveness of point-of-choice interventions is equivocal. This paper reports a new approach to worksite interventions, aimed at changing attitudes and, hence, behaviour.MethodsPre-testing of calorific expenditure messages used structured interviews with members of the public (n = 300). Effects of multi-component campaigns on stair climbing were tested with quasi-experimental, interrupted time-series designs. In one worksite, a main campaign poster outlining the amount of calorific expenditure obtainable from stair climbing and a conventional point-of-choice prompt were used (Poster alone site). In a second worksite, additional messages in the stairwell about calorific expenditure reinforced the main campaign (Poster + Stairwell messages site). The outcome variables were automated observations of stair and lift ascent (28,854) and descent (29,352) at baseline and for three weeks after the intervention was installed. Post-intervention questionnaires for employees at the worksites assessed responses to the campaign (n = 253). Analyses employed Analysis of Variance with follow-up Bonferroni t-tests (message pre-testing), logistic regression of stair ascent and descent (campaign testing), and Bonferroni t-tests and multiple regression (follow-up questionnaire).ResultsPre-testing of messages based on calorific expenditure suggested they could motivate stair climbing if believed. The new campaign increased stair climbing, with greater effects at the Poster + Stairwell messages site (OR = 1.52, 95% CI = 1.40-1.66) than Posters alone (OR = 1.24, 95% CI = 1.15-1.34). Follow-up revealed higher agreement with two statements about calorific outcomes of stair climbing in the site where they were installed in the stairwell, suggesting more positive attitudes resulted from the intervention. Future intentions for stair use were predicted by motivation by the campaign and beliefs that stair climbing would help weight control.ConclusionsMulti-component campaigns that target attitudes and intentions may substantially increase stair climbing at work.

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