Patients with rare diseases have cost NHS England more than £3.4 billion in the last 10 years, analysis shows.

The figures were collated using the Hospital Episode Statistics (HES) NHS Digital database of more than 60 million patients, with the research commissioned by health tech company Mendelian and carried out by Imperial College Health Partners (ICHP).

Using an analysis based on a cohort of 258,235 patients diagnosed with a rare disease during 2017/2018, it focused on hospital visits and activity in the lead-up to diagnosis over the prior 10 years.

Analysis of the data found a higher number of hospital visits and accompanying costs per rare disease patient when compared to the general patient population.

Although the rare disease cohort included in the assessment only made up 0.94% of the HES reported hospital population during 2017/2018, over the preceding 10 years they cost an average of at least two times more per patient compared with other patients who had a hospital visit during that year.

They found an average individual difference of more than £7,000.

Furthermore, in a comparison of 64 inpatient and outpatient procedures, the total cost for the rare disease patient cohort outweighed the costs of the comparative population in the majority of procedures.

Researchers said it is estimated that rare diseases affect 350 to 400 million people globally, while around one in 17 people will have a rare disease at some point in their lives.

Previous studies have shown that rare disease diagnosis may take between five to 30 years, depending on the disease and healthcare setting.

In the UK it takes an average of 5.6 years, eight clinicians (including four specialists) and three misdiagnoses before the correct rare disease is identified.

The team said their findings shed light on the cost and resource impact the lengthy process of diagnosing rare diseases is having on the NHS.

Head of clinical partnerships at Mendelian, Peter Fish, said: “The ‘diagnostic odyssey’ for rare diseases is often fraught with emotional turmoil and suboptimal care for patients, frustration for clinicians and is also extremely costly for hospitals and associated trusts.

“This new research has given us a rare insight into the extent of this financial burden on the NHS and will hopefully also help us along the path to effective solutions, not just in the UK but also globally.

“At Mendelian, our mission is to help solve the problems around identifying rare diseases by using cutting-edge technology to enable physicians and hospitals to diagnose faster and more accurately, to the benefit of both patients and the healthcare systems that support them.”

Julia Wilkins, head of data and analytics at ICHP, said: “The costs to the NHS highlighted by the research are in fact only the tip of the iceberg, due to the fact that routine healthcare data does not yet fully capture the true extent of the thousands of different rare disease classifications that can pass through the system.

“For example, the International Classification of Diseases (ICD-10) is believed to only account for approximately 5% of known rare diseases.

“Therefore, these recent findings might well be extrapolated in order to anticipate a complete picture of the impact of diagnosing rare diseases on the NHS, both in terms of cost and resource utilisation, which is most likely considerably larger than the estimate outlined.”