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Cost saving of switching to equivalent inhalers and its effect on health outcomes

Bloom CI, Douglas I, d’Ancona G, et al.

Thorax. 2019;74(11):1078–86.

DOI: 10.1136/thoraxjnl-2018-212957

In the UK, over 1.2 million people have a diagnosis of chronic obstructive pulmonary disease (COPD) and over 5.4 million people receive asthma treatment (estimations from 2012). Due to the high prevalence of respiratory diseases, 3 of the top 5 most expensive drugs in the National Health Service (NHS) budget in terms of total prescription costs are inhalers. Over £1.1 billion of the NHS budget is spent on asthma, with an additional £800 million spent directly on COPD. Switching inhalers to a cheaper alternative is often advocated as a cost-saving strategy despite the impact on patient’s health being unknown.

This study assessed the UK primary healthcare records of patients with asthma and chronic obstructive pulmonary disease (COPD) between 2000 and 2016. This study employed a self-controlled design by comparing patients at a time of risk (during the 3-month period after switching inhalers) to a time of reduced risk (pre-switch or post-adaptation their new prescription). Four outcomes were assessed: disease exacerbations, general practitioner consultations, non-specific respiratory events and adverse-medication events. Medication possession ratio (MPR) was calculated to assess adherence to treatment. The cost differences per equivalent dose were calculated from the 2017 National Health Service prices.

2% of the identified asthma inhaler users and 6% of the COPD inhaler users switched prescription. Inhaler switches between a brand-to-generic inhaler, and all other switches (brand-to-brand, generic-to-generic, generic-to-brand), were associated with reduced exacerbations (brand-to-generic: IRR=0.75, 95% CI 0.64 to 0.88; all other: IRR=0.79, 95% CI 0.71 to 0.88). No differences in gender, age, therapeutic class, inhaler device and inhaler-technique checks were found between the groups. The rate of consultations, respiratory-events and adverse-medication events did not change significantly (consultations: Incidence Rate Ratio (IRR)=1.00, 95% confidence interval (CI) 0.99 to 1.01; respiratory-events: IRR=0.96, 95% CI 0.95 to 0.97; adverse-medication-events: IRR=1.05, 95% CI 0.96 to 1.15). Adherence significantly increased post-switch (median MPR: pre-switch=54%, post-switch=62%; p<0.001). The temporary reduction in exacerbations may have been due to increased medication understanding.

The results suggest that financially driven switching occurs infrequently due to the belief that inhalers are not interchangeable. In contradiction, this study has shown that switching to an equivalent inhaler in patients with asthma or COPD appears to be safe and did not negatively affect patient’s health or healthcare utilisation, as only 5% of patients did not stay on their new inhaler. Additionally, switching inhalers could reduce the cost of treatment by £6 million. These findings have important clinical implications and could help redirect the respiratory healthcare budget towards more efficacious recipients. However, the study results must be interpreted with caution as data was not reported on whether the switch to a different inhaler was performed face to face, by phone or by letter. All medication changes should be performed with the patient face to face, while clinicians should also use the time with the patient to ensure that they are able to use their new therapies and understand the reasons behind the change.

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