Inhalation corticosteroids for COVID-19 - a real world data analysis on guideline adherence.

Background: The recommendation to consider prescribing inhalation corticosteroids to a subgroup of vulnerable COVID-19 patients was added to the Dutch medical guideline on November 11, 2021, and was also adopted by other countries during the pandemic.

Aim: To evaluate the adherence of general practitioners to this guideline, and whether real-world data quality is sufficient to study the effect of revised guidelines on prescribing behaviour.

Design & setting: A retrospective cohort study using Dutch primary care data from the Extramural LUMC Academic Network database, containing patient data of 129 general practices in the Leiden - The Hague area.

Method: We performed an interrupted time series analysis to measure the effect of the new guideline on the prescription rate of ICS, accounting for general trend and seasonal fluctuations.

Results: Between July 1, 2020 to August 1, 2022, 131,482 patients had 164,098 COVID-19 consultations. During this period, 1,709 patients received 2094 ICS prescriptions for COVID-19. After the guideline update, there was an instantaneous decrease in prescription rate (IRR 0.47, 95% CI 0.32-0.69). Prescription rate in the subgroup of vulnerable patients did not change significantly (IRR 0.93, 95% CI 0.66-1.32), while less vulnerable patients were significantly prescribed less (IRR 0.29, 95% CI 0.14-0.59).

Conclusion: The revision to COVID-19 guidelines had significant impact on general practitioners' prescription behaviour soon after publication: prescription rate remained constant for vulnerable patients, while less vulnerable patient were significantly prescribed less often. Using electronic health records it is feasible to assess changes in guideline adherence using interrupted time series.