Methods This historical cohort study of a broad asthma patient population in the Optimum Patient Care Research Database, examined asthma patients with 3+ eligible post-18th birthday peak expiratory flow rate (PEF) records (primary analysis), or records of forced expiratory flow in 1 second (FEV1) (sensitivity analysis). Adjusted linear growth models tested the association between mean annual exacerbation rate (AER) and lung function trajectory.
Results We studied 109,182 patients with follow-up ranging from 5-50 years, of which 75, 280 had data for all variables included in the adjusted analyses. For each additional exacerbation an estimated additional -1.34 L/min PEF per year (95% CI -1.23, -1.50) were lost. Patients with AERs >2/year and aged 18-24 years at baseline lost an additional -5.95 L/min PEF/year (95% CI -8.63, -3.28) compared to those with AER 0. These differences in the rate of LF decline between AER groups became progressively smaller as age at baseline increased. The results using FEV1 were consistent with the above.
Conclusion To our knowledge this study is the largest nationwide cohort of its kind and demonstrates that asthma exacerbations are associated with faster lung function decline. This was more prominent in younger patients, but was evident in older patients when it was related to lower starting lung function, suggesting a persistent deteriorating phenotype that develops in adulthood over time. Earlier intervention with appropriate management in younger asthma patients could be of value to prevent excessive lung function decline.
This study was conducted by the Observational and Pragmatic Research Institute (OPRI) Pte Ltd and was partially funded by Optimum Patient Care Global and AstraZeneca Ltd. No funding was received by the Observational & Pragmatic Research Institute Pte Ltd (OPRI) for its contribution.
The authors thank the UK primary care sites that contributed anonymised patient data to this study; Drs Jaco Voorham and Marjan Kerkhof for their contributions to the preparation and analysis of the data; and Audrey Ang and Andrea Teh Xin Yi for coordinating logistical and administrative support for the development of this manuscript. We also thank our Thorax peer reviewers for their in-depth comments and suggestions which greatly improved the quality of this article.