Fitting multilevel models in complex survey data with design weights: Recommendations

Abstract Background Multilevel models (MLM) offer complex survey data analysts a unique approach to understanding individual and contextual determinants of public health. However, little summarized guidance exists with regard to fitting MLM in complex survey data with design weights. Simulation work suggests that analysts should scale design weights using two methods and fit the MLM using unweighted and scaled-weighted data. This article examines the performance of scaled-weighted and unweighted analyses across a variety of MLM and software programs. Methods Using data from the 2005–2006 National Survey of Children with Special Health Care Needs (NS-CSHCN: n = 40,723) that collected data from children clustered within states, I examine the performance of scaling methods across outcome type (categorical vs. continuous), model type (level-1, level-2, or combined), and software (Mplus, MLwiN, and GLLAMM). Results Scaled weighted estimates and standard errors differed slightly from unweighted analyses, agreeing more with each other than with unweighted analyses. However, observed differences were minimal and did not lead to different inferential conclusions. Likewise, results demonstrated minimal differences across software programs, increasing confidence in results and inferential conclusions independent of software choice. Conclusion If including design weights in MLM, analysts should scale the weights and use software that properly includes the scaled weights in the estimation.</p

The effectiveness of interventions to change six health behaviours: a review of reviews

Background: Several World Health Organisation reports over recent years have highlighted the high incidence of chronic diseases such as diabetes, coronary heart disease and cancer. Contributory factors include unhealthy diets, alcohol and tobacco use and sedentary lifestyles. This paper reports the findings of a review of reviews of behavioural change interventions to reduce unhealthy behaviours or promote healthy behaviours. We included six different health-related behaviours in the review: healthy eating, physical exercise, smoking, alcohol misuse, sexual risk taking (in young people) and illicit drug use. We excluded reviews which focussed on pharmacological treatments or those which required intensive treatments (e. g. for drug or alcohol dependency). Methods: The Cochrane Library, Database of Abstracts of Reviews of Effectiveness (DARE) and several Ovid databases were searched for systematic reviews of interventions for the six behaviours (updated search 2008). Two reviewers applied the inclusion criteria, extracted data and assessed the quality of the reviews. The results were discussed in a narrative synthesis. Results: We included 103 reviews published between 1995 and 2008. The focus of interventions varied, but those targeting specific individuals were generally designed to change an existing behaviour (e. g. cigarette smoking, alcohol misuse), whilst those aimed at the general population or groups such as school children were designed to promote positive behaviours (e. g. healthy eating). Almost 50% (n = 48) of the reviews focussed on smoking (either prevention or cessation). Interventions that were most effective across a range of health behaviours included physician advice or individual counselling, and workplace- and school-based activities. Mass media campaigns and legislative interventions also showed small to moderate effects in changing health behaviours. Generally, the evidence related to short-term effects rather than sustained/longer-term impact and there was a relative lack of evidence on how best to address inequalities. Conclusions: Despite limitations of the review of reviews approach, it is encouraging that there are interventions that are effective in achieving behavioural change. Further emphasis in both primary studies and secondary analysis (e.g. systematic reviews) should be placed on assessing the differential effectiveness of interventions across different population subgroups to ensure that health inequalities are addressed.</p

The Cool Little Kids randomised controlled trial: Population-level early prevention for anxiety disorders

Background: The World Health Organization predicts that by 2030 internalising problems (e.g. depression and anxiety) will be second only to HIV/AIDS in international burden of disease. Internalising problems affect 1 in 7 school aged children, impacting on peer relations, school engagement, and later mental health, relationships and employment. The development of early childhood prevention for internalising problems is in its infancy. The current study follows two successful &lsquo;efficacy&rsquo; trials of a parenting group intervention to reduce internalising disorders in temperamentally inhibited preschool children. Cool Little Kids is a population-level randomised trial to determine the impacts of systematically screening preschoolers for inhibition then offering a parenting group intervention, on child internalising problems and economic costs at school entry.Methods/Design: This randomised trial will be conducted within the preschool service system, attended by more than 95% of Australian children in the year before starting school. In early 2011, preschool services in four local government areas in Melbourne, Australia, will distribute the screening tool. The &asymp;16% (n&asymp;500) with temperamental inhibition will enter the trial. Intervention parents will be offered Cool Little Kids, a 6-session group program in the local community, focusing on ways to develop their child&rsquo;s bravery skills by reducing overprotective parenting interactions. Outcomes one and two years post-baseline will comprise child internalising diagnoses and symptoms, parenting interactions, and parent wellbeing. An economic evaluation (costconsequences framework) will compare incremental differences in costs of the intervention versus control children to incremental differences in outcomes, from a societal perspective. Analyses will use the intention-to-treat principle, using logistic and linear regression models (binary and continuous outcomes respectively) to compare outcomes between the trial arms.Discussion: This trial addresses gaps for internalising problems identified in the 2004 World Health Organization Prevention of Mental Disorders report. If effective and cost-effective, the intervention could readily be applied at a population level. Governments consider mental health to be a priority, enhancing the likelihood that an effective early prevention program would be adopted in Australia and internationally.<br /

Intraoperative dural irradiation by customized 192IRIDIUM AND 90YTTRIUM brachytherapy plaques

After vertebral or paravertebral tumor resection, tumor cells may remain on the dura. Because a tumoricidal dose is difficult to achieve using external beam radiotherapy without exceeding the spinal cord tolerance, we developed intraoperative applicators to deliver additional dose to the dura. Eight patients with vertebral or paravertebral tumor underwent conformal external beam radiotherapy, tumor resection, and intraoperative radiotherapy to the dura involved by tumor. At surgery, vertebra, soft tissue, and epidural tumor were resected. A radioactive applicator plaque was placed on the dura to deliver 7.5–15 Gy, and then removed. Vertebral reconstruction and stabilization was completed. Chemotherapy was administered for large, high-grade sarcomas. We progressed through three plaque designs, initially 192Ir, subsequently liquid 90Y, and finally 90Y foil in a semicylindrical polycarbonate plaque, in the treatment of 8 patients. The low-energy 90Y β-emissions provided a more attractive depth dose profile than that achievable with iridium and gave negligible staff radiation exposure. The 90Y depth dose measured 29% at 2 mm and 9% at 4 mm from the surface of the foil plaque, with acceptable surface dose homogeneity. The average surface dose rate ranged from 18.7 to 47.6 cGy/min for the iridium plaques and 45.2 to 187.5 cGy/min for the 90Y plaques. The treatments have been without acute or late neurologic complications. The disease of 6 of 8 patients was locally controlled at median potential follow-up of 24 months. The 90Y foil applicator is technically elegant, easy to use, and superior to the earlier models. It has been incorporated into a protocol for spinal tumor treatment