Using Electronic Prescription Records to Estimate Asthma Severity

What is it about?

Asthma is normally treated in a step-wise manner, with increases in strength, or additional medicines added, if someone’s asthma isn’t responding or has not been brought under control with their current regimen. Researchers can rank treatment regimens by mapping them to the treatment guidelines written by the British Thoracic society (BTS), which are presented as five steps to move up or down as required. The first step is a low-strength inhaled corticosteroid (ICS) inhaler (for example, a Clenil beclometasone inhaler), which works to reduce the sensitivity of the airways to stop them swelling, which is what causes the symptoms of asthma. If this isn’t enough to reduce symptoms, a long-acting beta-2 agonist inhaler (known as a LABA) can be added, either as a combination inhaler with the ICS (like Symbicort or Seretide) or as a standalone inhaler. LABA is a longer acting version of the blue reliever inhaler, which works by actively opening up the airways. This can help the ICS to work more effectively, but also provides relief straight away. The third step is to increase the ICS from low to medium dose. The LABA might be removed, if it didn’t help at all, or replaced with a leukotriene receptor antagonist (LTRA, like Singulair Montelukast). LTRAs work by stopping a specific type of inflammation from happening in the airways. The next step is to increase to high-dose ICS, or supplement with any further add-on therapies, including LTRAs, and other airway opening treatments like theophylline or LAMA (LAMA, like Atrovent Ipratropium). Although not included in the BTS treatment steps, a long-term oral steroid treatment is the final recourse for those with particularly difficult to control asthma. Researchers sometimes use the step that is needed to control someone’s asthma as a way of describing how severe their asthma is. This approach might be used for medical research to work out if certain factors or exposures (like being female, or a parent being a smoker) could affect asthma. While we could ask people to report what medicines they are currently taking, a quicker and less intrusive way of gathering this data is by looking at their past prescriptions. It’s not an easy process to extract this data though, because a lot of the information that is needed is stored in the bulk of text within patient’s records and written by the clinician, rather than all the individual details being laid out in individual cells in an excel spreadsheet. Even once we have extracted the data, mapping the details to BTS treatment steps isn’t always obvious, as some people have slight deviations from the regimens (the combinations of medicines someone is taking regularly) recommended in the guidelines, to suit their specific needs. In this study, we used a Scottish prescribing record dataset, and extracted important information like the brand, strength, and dose. We then total the different medicines an individual is taking at the same time, and construct a regimen: for example, a low-dose ICS inhaler plus a long-acting beta-2 agonist (LABA) inhaler. We subsequently mapped each regimen to a treatment step within the steps range 1-5. Our dataset contained over 40 million prescriptions that related to just over 650,000 individuals over the period of January 2009 to March 2017. Of these, almost 4.5 million prescriptions were for asthma controller medications (not including blue reliever inhalers). We identified 110 unique regimens observed, of which the most common was high-strength ICS plus LABA (19% of prescriptions corresponded to this regimen). For 26% of prescriptions, the individual had not been prescribed any ICS (which is recommended for ALL patients in the BTS guidelines) within the last 120 days. Although this might occur sometimes due to late refills, or having previously obtained a higher quantity to see them through a holiday (for example), such a high rate is indicative that there are too many people who are not being properly treated, and are at risk for uncontrolled asthma and even asthma attacks.

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Photo by Sincerely Media on Unsplash

Photo by Sincerely Media on Unsplash

Why is it important?

Our paper provides a detailed and reproducible guide for other researchers to estimate asthma severity from prescriptions, and provides valuable insights into asthma treatment in Scotland. We hope that this is useful for other researchers, and allows them to conduct high-quality evaluations of asthma populations and risk factors. More crucially, however, we hope that better quality research will improve the quality of care for everyone with asthma.