In the Netherlands, the National Health Care Institute is responsible for advising the Dutch government on the reimbursement of new and existing health technologies such as pharmaceuticals, medical devices, and surgical but also long-term health care. The Institute uses Health Technology Assessment (HTA) as an important tool to formulate these reimbursement advices. The HTAs are organised based on the use of four decision criteria: necessity, effectiveness, cost-effectiveness and applicability; these criteria have originally been described by Dunning et al. (1991). Although the operationalization and standardisation of some of these criteria like effectiveness and, to a lesser extent, cost-effectiveness is well developed, this was less obvious for the criterion necessity. This criterion concerns among others the assessment of the severity (or burden) of disease that should be treated. The operationalization of necessity of care has been discussed since many years and already in 2001 it was proposed to use the so-called ‘proportional shortfall’ method that provides quantification for a particular definition of burden of illness (BoI). In recent years the burden of illness became more important in the Netherlands due to its relation to cost-effectiveness. Since 2015 the National Health Care Institute uses three reference values for cost-effectiveness in their reimbursement process. For treatments for more severe diseases higher cost-effectiveness rates are accepted than for less severe diseases. Therefor the operationalization and standardisation of burden of illness became an important topic in the Dutch health care reimbursement process and clarity was needed. The institute recently published a report called “Disease burden in practice” to give more insight into the (operationalisation and reporting of the) proportional shortfall method in the Dutch reimbursement process.