The National Child Development Study (NCDS) is a birth cohort study whose longitudinal design makes it suitable for examining the natural history of common diseases in childhood such as atopic eczema. We have analysed the age of onset and clearance rates for examined and/or reported eczema in 6877 children born during the period 3-9 March 1958 for whom linked data were available at birth and at the ages of 7, 11, 16 and 23 years. Of the 870 cases with examined or reported eczema by the age of 16 years, 66% had age of onset by the age of 7 years. Of the 571 children with reported or examined eczema by the age of 7 years, the proportion of children who were clear in terms of examined eczema or reported eczema in the last year at ages 11 and 16 years was 65% and 74%, respectively. These 'apparent' or short-term clearance rates fell to 53% and 65%, respectively, after allowance for subsequent recurrences in adolescence and early adulthood. Age of onset of community-ascertained cases of atopic eczema may be later than that reported in hospital-based studies. The long-term prognosis of childhood eczema may be worse than some previous studies have suggested, especially when subsequent recurrences are taken into account.

Focus groups have considerable potential for study of the attitudes and experiences of patients and health care providers within dermatology. This article describes the use of such groups, using specific dermatological examples.

Asking study participants for their views of treatment efficacy seems like a good idea in dermatological clinical trials, yet only about a quarter of the trials examined in this review did so. Even when such information was recorded, it was often poorly and incompletely reported and given low prominence within the trial report. Our study findings call for a more comprehensive uptake for including participant efficacy outcomes alongside other assessor outcomes in clinical trials and, when included, to report those outcomes in full.

ObjectivesRandomised controlled trials in healthcare increasingly include economic evaluations. Some show small differences which are not statistically significant. Yet these sometimes come to paradoxical conclusions such as: ‘the intervention is not clinically effective’ but ‘is probably cost-effective’. This study aims to quantify the extent of non-significant results and the types of conclusions drawn from them.DesignCross-sectional retrospective analysis of randomised trials published by the UK’s National Institute for Health Research (NIHR) Health Technology Assessment programme. We defined as ‘doubly null’ those trials that found non-statistically significant differences in both primary outcome and cost per patient. Paradoxical was defined as concluding in favour of an intervention, usually compared with placebo or usual care. No human participants were involved. Our sample was 226 randomised trial projects published by the Health Technology Assessment programme 2004 to 2017. All are available free online.ResultsThe 226 projects contained 193 trials with a full economic evaluation. Of these 76 (39%) had at least one ‘doubly null’ comparison. These 76 trials contained 94 comparisons. In these 30 (32%) drew economic conclusions in favour of an intervention. Overall report conclusions split roughly equally between those favouring the intervention (14), and those favouring either the control (7) or uncertainty (9).DiscussionTrials with ‘doubly null’ results and paradoxical conclusions are not uncommon. The differences observed in cost and quality-adjustedlife year were small and non-statistically significant. Almost all these trials were also published in leading peer-reviewed journals. Although some guidelines for reporting economic results require cost-effectiveness estimates regardless of statistical significance, the interpretability of paradoxical results has nowhere been addressed.ConclusionsReconsideration is required of the interpretation of cost-effectiveness analyses in randomised controlled trials with ‘doubly null’ results, particularly when economics favours a novel intervention.