Sam Abbott, Hannah Christensen, Ellen Brooks-Pollock
Background
The Enhanced Tuberculosis Surveillance (ETS) system is a routine surveillance system that collects data on all notified tuberculosis (TB) cases in England and is routinely used in research. Routine data often has a large amount of missing data which may introduce bias to analyses.
Methods
We used data on all notifications in the ETS for England (2000-2015). We summarised the proportion of missing data and then used logistic regression to explore the associations between missingness and demographic variables for the following outcomes: drug resistance; BCG status and year; date of symptom onset, diagnosis, notification, starting treatment, finishing treatment and death; and cause of death. For all date variables, we visualised the distribution annually and by month, identifying variables at risk of bias.
Results
All demographic variables considered were associated with data being missing for multiple outcomes. Missingness was not associated with all demographic variables for all outcomes. Associations that were present did not all have the same direction of effect. We found that the date of symptom onset and the date of ending treatment had a high proportion of cases occurring in January and on the 1st and 14th of each month indicating the presence of potential bias.
Conclusions
Missingness in outcomes was associated with multiple demographic variables. These associations could not be generalised, preventing a systematic approach to dealing with missingness and indicating that domain knowledge is required. The identified associations may induce bias, meaning that multiple imputation may be beneficial for analyse using this data source - or other similar surveillance data. Our findings should be used to motivate the use of imputation and to inform the specification of imputation models that include auxiliary variables.
Reproducibility
Repository structure
The repository is structured as an R package. It has the following structure:
-
data-raw: Raw data processing. -
data: Processed data. -
R: Supporting R functions. -
docs:Documentation for R code. -
vignettes: Analysis paper, results, and analysis plan. -
peer-review: Documentation required for peer review.
Manual install
Install R (analysis run with
3.6.1) and Rstudio (alternatively use Docker as outlined below).Download the analysis folder from https://github.com/seabbs/ETSMissing/archive/master.zip or use
git clone, as follows, in the command line (not the R terminal).
Once this has been downloaded click on the project file (
ETSMissing.Rproj).Install the analysis dependencies and build the package using the following. To enable more robust reproducibility consider using the
checkpointpackage versioned locked to R3.6.1.
#install.packages("devtools")
# To build locally
devtools::install_dev_deps(dependencies = TRUE)
devtools::install()
# Alternatively to remote install
devtools::install_github("seabbs/ETSMissing", dependencies = TRUE)Load the analysis results by running
vignettes/paper.Rmd. Alternatively the complete analysis (along with documentation) can be reconstructed usingmakein the project root directory.See
data-rawfor data processing and the documentation for implementation details.
Docker
This analysis was developed in a docker container based on the tidyverse docker image. To run the docker image run:
The rstudio client can be found on port :8787 at your local machines ip. The default username:password is assessbcgpolicychange:assessbcgpolicychange, set the user with -e USER=username, and the password with - e PASSWORD=newpasswordhere. The default is to save the analysis files into the user directory.
If you have access to the required underlying raw data (see tbinenglanddataclean) then the entire analysis can be reproduced from scratch by adding the following to the docker run command, with the data saved into data/tb_data. The data requirements, and structure, can be found here.
Alternatively the analysis environment can be accessed via binder.
