title: Network meta-analysis of (individual patient) time to event data alongside (aggregate) count data.
abstract: BACKGROUND
  Network meta-analysis methods extend the standard pair-wise framework to allow simultaneous comparison of multiple interventions in a single statistical model. Despite published work on network meta-analysis mainly focussing on the synthesis of aggregate data, methods have been developed that allow the use of individual patient-level data specifically when outcomes are dichotomous or continuous. This paper focuses on the synthesis of individual patient-level and summary time to event data, motivated by a real data example looking at the effectiveness of high compression treatments on the healing of venous leg ulcers.
  
  
  METHODS
  This paper introduces a novel network meta-analysis modelling approach that allows individual patient-level (time to event with censoring) and summary-level data (event count for a given follow-up time) to be synthesised jointly by assuming an underlying, common, distribution of time to healing. Alternative model assumptions were tested within the motivating example. Model fit and adequacy measures were used to compare and select models.
  
  
  RESULTS
  Due to the availability of individual patient-level data in our example we were able to use a Weibull distribution to describe time to healing; otherwise, we would have been limited to specifying a uniparametric distribution. Absolute effectiveness estimates were more sensitive than relative effectiveness estimates to a range of alternative specifications for the model.
  
  
  CONCLUSIONS
  The synthesis of time to event data considering individual patient-level data provides modelling flexibility, and can be particularly important when absolute effectiveness estimates, and not just relative effect estimates, are of interest.
authors.affiliation: Centre for Health Economics, University of York, Heslington, York YO10 5DD, UK. pedro.saramago@york.ac.uk.
authors.forename: Pedro
authors.initials: P
authors.lastname: Saramago
authors.forename: Ling-Hsiang
authors.initials: LH
authors.lastname: Chuang
authors.forename: Marta O
authors.initials: MO
authors.lastname: Soares
mesh_terms: D058128:Compression Bandages; D003627:Data Interpretation, Statistical; D006801:Humans; D007871:Leg Ulcer / Q000628:therapy*; D015233:Models, Statistical; D013995:Time; D014647:Varicose Ulcer / Q000628:therapy*