Validation of the recording of idiopathic pulmonary fibrosis in routinely collected electronic healthcare records in England

Incidence and prevalence of asthma, chronic obstructive pulmonary disease and interstitial lung disease between 2004 and 2023: harmonised analyses of longitudinal cohorts across England, Wales, South-East Scotland and Northern Ireland

BACKGROUND

We describe the epidemiology of asthma, chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD) from 2004 to 2023 in England, Wales, Scotland and Northern Ireland (NI) using a harmonised approach.

METHODS

Data from the National Health Service England (NHSE), Clinical Practice Research Datalink Aurum in England, Secure Anonymised Information Linkage Databank in Wales, DataLoch in South-East Scotland and the Honest Broker Service in NI were used. A harmonised approach to COPD, asthma and ILD case definitions, study designs and study populations across the four nations was performed. Age-sex-standardised incidence rates and point prevalence were calculated between 2004 and 2023 depending on data availability. Logistic and negative binomial regression compared incidence and prevalence rates between the start and end of each study period. Linear extrapolation projected incidence rates between 2020 and 2023 to illustrate how observed and projected rates differed.

RESULTS

Incidence rates were lower in 2019 versus 2005 for asthma (England: incidence rate ratio 0.89, 95% CI 0.88 to 0.90; Wales: 0.66, 0.65 to 0.68; Scotland: 0.67, 0.64 to 0.71; NI: 0.84, 0.81 to 0.86), COPD (England: 0.83, 0.82 to 0.85; Wales: 0.67, 0.65 to 0.69) and higher for ILD (England: 3.27, 3.05 to 3.50; Wales: 1.39, 1.27 to 1.53; Scotland: 1.63, 1.36 to 1.95; NI: 3.03, 2.47 to 3.72). In NHSE, the incidence of asthma was similar in June 2023 versus November 2019, but lower for COPD and higher for ILD. Prevalence of asthma in 2019 in England, Wales, Scotland and NI was 9.7%, 15.9%, 13.2% and 7.0%, respectively, for COPD 4.5%, 5.1%, 4.4% and 3.0%, and for ILD 0.4%, 0.5%, 0.6% and 0.3%. Projected incidence rates were 2.8, 3.4 and 1.8 times lower for asthma, COPD and ILD compared with observed rates at the height of the pandemic.

INTERPRETATION

Asthma, COPD and ILD affect over 10 million people across the four nations, and a substantial number of diagnoses were missed during the pandemic.

Incidence and survival of interstitial lung diseases in the UK in 2010-2019

Background

With the introduction of the antifibrotic drugs targeting progressive pulmonary fibroses, it becomes imperative to provide reliable contemporary estimates of the most common interstitial lung diseases. We aimed to provide contemporary estimates of the incidence and survival of idiopathic pulmonary fibrosis (IPF), hypersensitivity pneumonitis (HP) and connective tissue disease-associated interstitial lung disease (CTD-ILDs), and to compare their survival to that of the general population. To do this we have used data extracted from the Optimum Patient Care Research Database (OPCRD).

Methods

In this matched cohort study, we extracted incident cases of HP, CTD-ILD and IPF, and age and sex matched controls for each case, for the years 2010-2019. We calculated annual incidence rates and analysed incidence trends over time using segmented regression modelling. We estimated survival for cases and controls using the Kaplan-Meier model.

Results

We extracted data for 18 914 incident cases of interstitial lung diseases between 2010 and 2019 from the OPRCD. Incidence rates varied across the different diseases, with rates of 18.12, 7.96 and 2.63 per 100 000 person-years for IPF, CTD-ILD and HP, respectively. 5-year survival for IPF, CTD-ILD and HP was 40%, 54% and 66%, respectively, and this was generally ∼50% lower than that of the general population.

Conclusion

Our population-based study emphasises the considerable burden of interstitial lung diseases, with >20 000 new cases diagnosed each year in the UK, many of whom will be eligible for antifibrotic drugs.

Commonly prescribed medications and risk of pneumonia and all-cause mortality in people with idiopathic pulmonary fibrosis: a UK population-based cohort study

BACKGROUND

A growing body of evidence suggests that prolonged use of inhaled corticosteroids (ICS) and proton pump inhibitors (PPIs) is associated with increased risks of pneumonia. A substantial proportion of people with idiopathic pulmonary fibrosis (IPF) are prescribed PPIs or ICS to treat common comorbidities, giving rise to concerns that use of these medications may be associated with potential harms in this patient population.

METHODS

We used UK Clinical Practice Research Datalink (CPRD) Aurum primary care data linked to national mortality and hospital admissions data to create a cohort of people diagnosed with IPF on or after 1 January 2010. Patients were assigned to one of three exposure categories according to their prescribing history in the 12 months prior to IPF diagnosis as follows: "regular" users (≥ 4 prescriptions), "irregular" users (1-3 prescriptions) and "non-users" (no prescriptions). We explored the association between PPI/ICS prescription and pneumonia hospitalisation and all-cause mortality using multinomial Cox regression models.

RESULTS

A total of 17,105 people met our study inclusion criteria; 62.6% were male and 15.9% were current smokers. Median age at IPF diagnosis was 76.7 years (IQR: 69.6-82.7). 19.9% were regularly prescribed PPIs, and 16.0% ICS, prior to IPF diagnosis. Regular prescribing of PPIs and ICS was positively associated with hospitalisation for pneumonia; the adjusted HR for pneumonia hospitalisation comparing regular PPI users with non-users was 1.14 (95%CI: 1.04-1.24); for regular ICS users the corresponding HR was 1.40 (95%CI: 1.25-1.55). We also observed a small increased risk for all-cause mortality in the "regular ICS user" group compared with the "non-user" control group (HRadj = 1.19, 1.06-1.33). We found no evidence of an association between PPI prescribing and all-cause mortality.

CONCLUSION

Prolonged prescription of medications used to treat common comorbidities in IPF may be associated with increased risks for severe respiratory infections. These findings point to a need to adopt an adequate risk-benefit balance approach to the prescribing of ICS-containing inhalers and PPIs in people with IPF without evidence of comorbidities, especially older patients and/or those with more advanced disease in whom respiratory infections are more likely to result in poorer outcomes.

Pulmonary fibrosis and lung cancer: an analysis of the Clinical Practice Research Datalink linked to the National Cancer Registration Dataset

We quantified the proportion of diagnoses of pulmonary fibrosis (PF) among 25 136 people with lung cancer and 250 583 matched controls and compared the natural history of lung cancer in people with and without PF. Diagnoses of PF were more common in people with lung cancer than those without (1.5% vs 0.8%, OR 1.97; 95% CI 1.77 to 2.21). Within people with PF, squamous cell carcinoma was more (22.9% vs 19.1%), and adenocarcinoma was less common (18.0% vs 21.3%). People with PF were less likely to have stage 4 disease at diagnosis (OR 0.43, 95% CI 0.28 to 0.65) but their survival was worse.

Mortality trends in idiopathic pulmonary fibrosis in Europe between 2013 and 2018

BACKGROUND

Previous research has suggested that the incidence of idiopathic pulmonary fibrosis (IPF) is increasing in the UK and elsewhere. The aim of this study is to provide contemporary estimates of IPF mortality rates across 24 European Union (EU) countries from 2013 to 2018, using death certificate data from the European Statistics Institution (EUROSTAT) database.

METHODS

We extracted country data for IPF (International Classification of Diseases, 10th Revision: code J84.1) mortality from the EUROSTAT dataset. We calculated country-, age- and sex-specific death registration rates between 2013 and 2018. We used direct standardisation to compare rates between countries. We calculated annual trends in mortality rate ratios using a segmented regression model.

RESULTS

The overall standardised mortality rate in 24 EU countries during this period was 3.90 (95% CI 3.80-3.90) per 100 000 person-years, with the rate rising from 3.70 in 2013 to 4.00 in 2018 (average annual percent change 1.74%, 95% CI 0.91-2.59%). We observed substantial inter-country differences, with the highest rates detected in Ireland, the UK and Finland, the lowest rate in Bulgaria, and middle rates in Germany, Greece, Italy, the Netherlands, Portugal and Slovenia.

CONCLUSIONS

The IPF mortality rate is increasing across Europe. There are currently more than 17 000 deaths recorded from IPF each year in Europe but the marked geographical differences we observed suggest that this figure may underestimate the true rate considerably.

Incidence, prevalence and mortality of idiopathic pulmonary fibrosis in England from 2008 to 2018: a cohort study

BACKGROUND

Owing to discrepancies in methodologies and how idiopathic pulmonary fibrosis (IPF) is diagnosed it is challenging to establish a consistent understanding of the disease burden In the UK, over 10 years ago, the incidence and prevalence of IPF were reported as 2.8-8.7 per 100 000 person-years (from 2000 to 2012) and 39 per 100 000 persons (in 2012), respectively. Here, we estimated the incidence and prevalence of IPF in England from 2008 to 2018 and investigated IPF mortality.

METHODS

Using Clinical Practice Research Datalink Aurum and Hospital Episode Statistics (HES) linked datasets, we estimated incidence and prevalence using four validated diagnostic-code-based algorithms. Using the registered number of deaths (from Office of National Statistics) with the underlying cause being recorded as IPF, we estimated IPF mortality for the same period.

RESULTS

Using Aurum-based definitions, incidence increased over time by 100% for Aurum narrow (3-6.1 per 100 000 person-years) and by 25% for Aurum broad (22.4-28.6 per 100 000 person-years). However, using HES-based definitions showed a decrease in incidence over the same period and lay between the two extremes derived for Aurum-based definition. IPF mortality in 2018 was 7.9 per 100 000 person-years and increased by 53% between 2008 and 2018.

INTERPRETATION

When using best-case definitions, incidence rose throughout the study period. Scaling this to England's population (2018), our best estimate would be in the range of 8000-9000 new cases per year which is higher than previously reported estimates (5000-6000). This increased burden in the new cases of IPF each year impacts future health service planning and resource allocation.

A Harmonised Approach to Curating Research-Ready Datasets for Asthma, Chronic Obstructive Pulmonary Disease (COPD) and Interstitial Lung Disease (ILD) in England, Wales and Scotland Using Clinical Practice Research Datalink (CPRD), Secure Anonymised Information Linkage (SAIL) Databank and DataLoch

Background

Electronic healthcare records (EHRs) are an important resource for health research that can be used to improve patient outcomes in chronic respiratory diseases. However, consistent approaches in the analysis of these datasets are needed for coherent messaging, and when undertaking comparative studies across different populations.

Methods and Results

We developed a harmonised curation approach to generate comparable patient cohorts for asthma, chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD) using datasets from within Clinical Practice Research Datalink (CPRD; for England), Secure Anonymised Information Linkage (SAIL; for Wales) and DataLoch (for Scotland) by defining commonly derived variables consistently between the datasets. By working in parallel on the curation methodology used for CPRD, SAIL and DataLoch for asthma, COPD and ILD, we were able to highlight key differences in coding and recording between the databases and identify solutions to enable valid comparisons.

Conclusion

Codelists and metadata generated have been made available to help re-create the asthma, COPD and ILD cohorts in CPRD, SAIL and DataLoch for different time periods, and provide a starting point for the curation of respiratory datasets in other EHR databases, expediting further comparable respiratory research.