IPF is characterised by acute exacerbations which result in permanent and substantially reduced lung function. A single exacerbation can cause as much as 20% decline in percent predicted forced vital capacity (FVC). Half of people with idiopathic pulmonary fibrosis may die within 30 days of an acute exacerbation. Causes are unknown, however risk factors include cigarette smoking, acid reflux disease (GERD) and certain viral infections. There is also evidence for some genetic predisposition. The 5-year survival for IPF is between 20-40%, higher than colon cancer, multiple myeloma and bladder cancer.
Since the application of the lung allocation score (LAS), which prioritises transplant candidates based on survival probability, IPF has become the most common indication for lung transplantation in the USA. Following lung transplantation, five-year survival rates are around 50% and some patients may live with the disease for 10-20 years.
It is difficult to diagnose IPF as this involves surgical lung biopsy followed by identifying specific combinations of radiologic and histopathologic patterns. Such as the presence of ‘usual interstitial pneumonia’ (UIP) on High Resolution Computed Tomography (HRCT). However the ‘honeycombing’ pattern, required for the diagnosis of UIP on HRCT, is prone to significant interobserver variability even amongst expert radiologists. Furthermore, 10% patients presenting with an atypical UIP pattern cannot undergo surgical lung biopsy due to age, advanced disease, or poor clinical conditions. Potentially limiting their access to available treatments, as these patients may not fall into any diagnostic category. Multidisciplinary Team (MDT) discussion involving clinicians, radiologists, pathologists, and rheumatologists and thoracic surgeons is therefore recommended before a final diagnosis is made.
In the UK, the generic medication Pirfenidone is normally offered to people whose disease meets the NICE guidance criteria of a predicted FVC of 50–80%. This group represents around half of the IPF population. However about a third of patients cannot tolerate this medication. Mainly due to Gastrointestinal side effects including anorexia, dyspepsia, gastroesophageal reflux syndrome, nausea, and constipation.
In 2016 NICE approved the antifibrotic Nintedanib, for patients with an FVC between 50-80%. So long as treatment is stopped if disease progresses, as confirmed by a 10% or greater decline in percent predicted FVC in any 12-month period. Despite evidence showing these medications can slow progression at earlier disease stages, when exacerbations may be less frequent and severe.
Recent evaluation of the British Thoracic Society’s Interstitial Lung Disease Registry showed only 44% of the cohort received anti-fibrotic therapies, less than the 57% of eligible patients, with 44% being ineligible. NICE recently announced it would be taking a proportionate approach to some technology appraisals, applying a new streamlined approach to medicines similar to ones they've already assessed, including Nintedanib when forced vital capacity is above 80% predicted.
In the UK, the BTS ILD registry evaluated 2474 cases between 2013 – 2019. Most patients were male (79%) with a mean age of 74 years and 66% being ex-smokers. Worldwide incidence of IPF is thought to be between 3–9 per 100 000 per year based on conservative estimates from Europe and North America. Meaning IPF is comparable to that of several malignancies, including stomach, liver, testicular and cervical cancers.
A 2018 systematic review of the Economic Literature in IPF identified 18 studies with cost evidence, the majority being retrospective cohort analyses of claims data.
- Common costs were hospitalisation, emergency room visits, and acute exacerbation events.
- Per patient costs were estimated to be around $20,000 per year, (2.5– 3.5 times mean national health care expenditure per person in North America).
- Treatment costs were between 8–10% of the total costs
- Estimates on the absolute level of HRQoL via EQ-5D varied between 0.67 - 0.8.
- Costs for new treatments were around $90,000 per year, with total HRQoL benefits of this treatment around 3-4 QALYs.
Only one discrete choice experiment, of 33 patients, has been conducted since the introduction of antifibrotic therapy. That feasibility study showed improving lung function was over twice as important as improving shortness of breath. Patients also felt it was around 2.5 times more important to decreasing risk of gastrointestinal problems compared to decreasing risk of sun sensitivity or risk of liver injury. Improving efficacy in terms of lung function was also 1.6 times as important as decreasing risk of gastrointestinal problems.
HCD believes it is important to further evaluate patient preferences in IPF. Including into tolerability, lung transplantations and how anti-fibrotic therapy is applied and discontinued. For further information and an informal chat please email: email@example.com