March 23, 2020

Recently Inverse Probability of Treatment Weighting (IPTW) using the propensity score has been proposed as an alternative to standard regression methods for baseline covariate adjustment in the analysis of randomized trials (Williamson et al. 2013). Motivated by some recent small trial analyses we explored the properties of IPTW for covariate adjustment within small trial settings. A simulation study and a re-analysis of a pediatric eczema trial involving 60 children revealed the performance of the IPTW variance estimator proposed by Williamson et al. was sub-optimal with smaller sample sizes. We therefore caution against the use of IPTW in small sample settings without small-sample modifications when the sample size is less than 150 and particularly when the sample size <100. In larger samples IPTW using the propensity score method can however be a useful tool for adjustment. When IPTW is used with large samples we demonstrate how the bootstrap variance may be a simpler route to variance estimation, given this incorporates the estimation of the propensity score.

February 11, 2020

Anca went to visit the London PHASTAR team in Chiswick for their monthly company meeting to present some of the research that’s been going on at ICTU, as well as her systematic review that investigates how rescue medication is defined, reported, and adjusted for in randomised controlled trials. It was also amazing to hear Jennifer Roger’s presentation describing her experience with her BBC Watchdog appearance, where companies within a different industry were ranked to establish who was the best and who was the worst when considering factors such as complaints, customer satisfaction, and cost. 

February 10, 2020

The protocol for an individual patient data meta-analysis to establish whether early skin care interventions, such as moisturisers, can prevent eczema or food allergy is now available. Published in the Cochrane database, this protocol provides details of the planned analyses that will be conducted by Suzie Cro and Victoria Cornelius. The primary analysis will estimate the pooled treatment policy effect of early skincare interventions on eczema and food allergy. Sensitivity analysis will also explore the pooled effect of complying with early skin care intervention. Subgroup analyses will explore whether risk for atopy, based on genotype and family history are associated with the pooled treatment effect. Results coming later this year!

February 07, 2020

PSI have recently launched a new visualisation special interest group (SIG). The group aims are to train statisticians and quantitative scientists about effective visualisations to look beyond tables alone. This group is led by Alexander Schacht of UCB and includes our own Rachel Phillips as a core member. The SIG’s first initiative, “Wonderful Wednesdays” will teach participants about visualisation principles and allow them to apply the techniques they learn to examples from the field of healthcare. To learn more about the initiative and how to get involved follow the link below:

January 31, 2020

The new MRC-NIHR Trials Methodology Research Partnership Statistical Analysis Working group  (SAWG) is now open to expressions of interest to join. If you are researching/interested in developing and applying methods for the statistical analysis of clinical trials we encourage you to join. This group is being co-led by Richard Emsley (KCL) and Tim Morris (UCL) and includes our own Suzie Cro as one of the core members. Additional details on the groups remit and form to join can be found at the below link.