Background Natural or quasi experiments are appealing for public health research because they enable the evaluation of events or interventions that are difficult or impossible to manipulate experimentally, such as many policy and health system reforms. However, there remains ambiguity in the literature about their definition and how they differ from randomized controlled experiments and from other observational designs. We conceptualise natural experiments in the context of public health evaluations and align the study design to the Target Trial Framework. Methods A literature search was conducted, and key methodological papers were used to develop this work. Peer-reviewed papers were supplemented by grey literature. Results Natural experiment studies (NES) combine features of experiments and non-experiments. They differ from planned experiments, such as randomized controlled trials, in that exposure allocation is not controlled by researchers. They differ from other observational designs in that they evaluate the impact of events or process that leads to differences in exposure. As a result they are, in theory, less susceptible to bias than other observational study designs. Importantly, causal inference relies heavily on the assumption that exposure allocation can be considered ‘as-if randomized’. The target trial framework provides a systematic basis for evaluating this assumption and the other design elements that underpin the causal claims that can be made from NES. Conclusions NES should be considered a type of study design rather than a set of tools for analyses of non-randomized interventions. Alignment of NES to the Target Trial framework will clarify the strength of evidence underpinning claims about the effectiveness of public health interventions.

BackgroundPsychotropic medications are frequently used to treat challenging behaviour in children with intellectual disabilities, despite a lack of evidence for their efficacy. This systematic review and meta-analysis aimed to determine the safety and efficacy of pharmacological interventions for challenging behaviour among children with intellectual disabilities.MethodsElectronic databases were searched and supplemented with a hand search of reference lists and trial registries. Randomised controlled trials of pharmacological interventions for challenging behaviour among children with intellectual disabilities were included. Data were analysed using meta-analysis or described narratively if meta-analysis was not possible. For quality assessment, the Cochrane Risk of Bias tool and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach were used.ResultsFourteen studies including 912 participants met inclusion criteria. Antipsychotic medication reduced challenging behaviour among children with intellectual disabilities in the short-term (SMD = −1.09, p < 0.001 for risperidone; SMD = −0.64, p <0.001 for aripiprazole). However, there were significant side-effects including elevated prolactin levels (SMD = 3.22, p < 0.001) and weight gain (SMD = 0.82, p < 0.001). Evidence was inconclusive regarding the effectiveness of anticonvulsants and antioxidants for reducing challenging behaviour. The quality of all evidence was low and there were no long term follow up studies.ConclusionsAntipsychotic medications appear to be effective for reducing challenging behaviour in the short-term among children with intellectual disabilities, but they carry a risk of significant side effects. Findings from this review must be interpreted with caution as studies were typically of low quality and most outcomes were based on a small number of studies. Further long-term, high-quality research is needed to determine the effectiveness and safety of psychotropic medication for reducing challenging behaviour.Electronic supplementary materialThe online version of this article (doi:10.1186/s12888-015-0688-2) contains supplementary material, which is available to authorized users.

Fetal alcohol spectrum disorders (FASDs) are lifelong disabilities caused by prenatal alcohol exposure. Prenatal alcohol use is common in the UK, but FASD prevalence was unknown. Prevalence estimates are essential for informing FASD prevention, identification and support.We applied novel screening algorithms to existing data to estimate the screening prevalence of FASD. Data were from a population-based cohort study (ALSPAC), which recruited pregnant women with expected delivery dates between 1991 and 1992 from the Bristol area of the UK. We evaluated different missing data strategies by comparing results from complete case, single imputation (which assumed that missing data indicated no exposure and no impairment), and multiple imputation methods.6.0% of children screened positive for FASD in the analysis that used the single imputation method (total N = 13,495), 7.2% in complete case analysis (total N = 223) and 17.0% in the analysis with multiply imputed data (total N = 13,495). A positive FASD screen was more common among children of lower socioeconomic status and children from unplanned pregnancies. Our analyses showed that the complete case and single imputation methods that are commonly used in FASD prevalence studies are likely to underestimate FASD prevalence.Although not equivalent to a formal diagnosis, these screening prevalence estimates suggest that FASD is likely to be a significant public health concern in the UK. Given current patterns of alcohol consumption and recent changes in prenatal guidance, active case ascertainment studies are urgently needed to further clarify the current epidemiology of FASD in the general population of the UK.

An uncontrolled study with process evaluation was conducted in three U.K. community maternity sites to establish the feasibility and acceptability of delivering a novel breastfeeding peer-support intervention informed by motivational interviewing (MI;Mam-Kind). Peer-supporters were trained to deliver the Mam-Kind intervention that provided intensive one-to-one peer-support, including (a) antenatal contact, (b) faceto-face contact within 48 hr of birth, (c) proactive (peer-supporter led) alternate day contact for 2 weeks after birth, and (d) mother-led contact for a further 6 weeks.Peer-supporters completed structured diaries and audio-recorded face-to-face sessions with mothers. Semistructured interviews were conducted with a purposive sample of mothers, health professionals, and all peer-supporters. Interview data were analysed thematically to assess intervention acceptability. Audio-recorded peer-support sessions were assessed for intervention fidelity and the use of MI techniques, using the MITI 4.2 tool. Eight peer-supporters delivered the Mam-Kind intervention to 70 mothers in three National Health Service maternity services. Qualitative interviews with mothers (n = 28), peer-supporters (n = 8), and health professionals (n = 12) indicated that the intervention was acceptable, and health professionals felt it could be integrated with existing services. There was high fidelity to intervention content; 93% of intervention objectives were met during sessions. However, peer-supporters reported difficulties in adapting from an expert-by-experience role to a collaborative role. We have established the feasibility and acceptability of providing breastfeeding peer-support using a MI-informed approach. Refinement of the intervention is needed to further develop peer-supporters' skills in providing mother-centred support. The refined intervention should be tested for effectiveness in a randomised controlled trial.