Histiocytic disease data story

This paper looked at epidemiology of histiocytic diseases, which have been identified as an understudied set of conditions. Histiocytic disorders are a group of diseases that occur when there is an over-production of white blood cells known as histiocytes that can lead to organ damage and tumour formation.

One of the histiocytic diseases is Langerhans cell histiocytosis (LCH), which is a cancer. Another is a rare disease called haemophagocytic lymphohistiocytosis (HLH). HLH is often associated with cancer. Having rare disease and cancer data available for England in the National Disease Registration Service (NDRS) presents a unique opportunity for studying histiocytic disease.

Joe West, who is professor of epidemiology at Nottingham University, worked with the team at NDRS to get a better understanding of both LCH and HLH.

There is an overall lack of information about histiocytic diseases. An international definition of LCH was only agreed in 2013, when it began to be collected by cancer registers. No large-scale population based study had been undertaken looking at children and adults, so the true incidence of LCH was unknown. HLH is a rare and often fatal disease that can occur at any age with multiple underlying causes. Diseases such as HLH are traditionally difficult to study.

This work will help raise awareness amongst clinicians of both HLH and LCH. It also means the data is available to inform healthcare planning and to underpin efforts to improve outcomes for patients.

A method was devised to identify individuals with HLH in the routinely collected data, which means that the study team were able to examine the trends of the incidence of HLH as well as factors affecting the survival of people with the disease.

The study was funded by the patient charity Histio UK. Nottingham University worked with NDRS and a wider network of clinicians and academics from multiple hospital trusts and universities.

For LCH the most recently released data from the National Cancer Registration Dataset (NCRD) was used for this study. The NCRD holds the population-based national cancer registry for England and is linked to other data sets for analysis purposes.

To develop a cohort for this study, a method was developed for identifying patients with HLH using hospital episodes statistics (HES) & Office for National Statistics (ONS) mortality data.

This is the first project where the NDRS rare disease data was linked to cancer data.

The study team, led by Joe West, has published four papers.

The LCH incidence paper includes the largest population-based cohort ever published. For the first time this study shows that a higher incidence and lower survival are associated with deprivation. Continued registration of HLH by the National Congenital Anomaly and Rare Disease team (NCARDRS) at NDRS will allow for monitoring long term incidence and patient outcomes, and lead to better understanding of survival and treatment options.

It will also help with a new platform that has been established with the aim of bringing together expertise from across the UK rare disease research system to improve diagnosis and treatment through better understanding of the disease. The UK Rare Disease Research Platform is made up of a central coordination and administrative hub and 11 specialist nodes based at universities across the UK. One of these nodes, HisitoNode, based at Newcastle University, will be working with NDRS to build on the work done to date to further improve the understanding of these conditions.