Seasonal patterns of Asthma medication fills among diverse populations of the United States

ABSTRACT

Objective: Nonadherence to controller and overuse of reliever asthma medications are associated with exacerbations. We aimed to determine patterns of seasonal asthma medication use and to identify time period(s) during which interventions to improve medication adherence could reduce asthma morbidity. Methods: We conducted a retrospective cohort study of asthmatics 4–50 years of age and enrolled in three diverse health insurance plans. Seasonal patterns of medications were reported by monthly prescription fill rates per 1000 individuals with asthma from 1998 to 2013, and stratified by healthcare plan, sex, and age. Results: There was a distinct and consistent seasonal fill pattern for all asthma medications. The lowest fill rate was observed in the month of July. Fills increased in the autumn and remained high throughout the winter and spring. Compared with the month of May with high medication fills, July represented a relative decrease of fills ranging from 13% (rate ratio, RR: 0.87, 95% confidence interval, 95%CI: 0.72–1.04) for the combination of inhaled corticosteroids (ICS) + long acting beta agonists (LABA) to 45% (RR: 0.55, 95%CI: 0.49–0.61) for oral corticosteroids. Such a seasonal pattern was observed each year across the 16-year study period, among healthcare plans, sexes, and ages. LABA containing control medication (ICS+LABA and LABA) fill rates were more prevalent in older asthmatics, while leukotriene receptor antagonists were more prevalent in the younger population. Conclusions: A seasonal pattern of asthma medication fill rates likely represents a reactive response to a loss of disease control and increased symptoms. Adherence to and consistent use of asthma medications among individuals who use medications in reaction to seasonal exacerbations might be a key component in reducing the risk of asthma exacerbations.

KEYWORDS:

• Asthma
• medication fills
• seasonality
• medication adherence
• exacerbations

Acknowledgements

The authors would like to thank the Navy and Marine Corps Public Health Center for its support during the conduct of this study.

Disclosure

The views expressed in this manuscript are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense or the United States Government.

Author contributions

KNT participated in study design and results interpretation, drafted and edited the manuscript. TG participated in study design, analyzed data, interpreted the results, and edited the manuscript. PW led the study design, was involved in data analysis and results interpretation, edited the manuscript, and obtained funding for the study. TVH oversaw the study design, was involved in data analysis and results interpretation, edited the manuscript, and obtained funding for the study. RLL, AME, CS, NMS, ACW, CI, MGB, EM, JM, and EKL participated in study design and results interpretation, and edited the manuscript.

Declaration of interest

RLL, AME, ACW, CI, MGB, and JM report no conflict of interest. TVH reports personal fees from Regeneron and Novavax and American Journal of Respiratory and Critical Care Medicine and grants from NIH report grant from NIH during the conduct of the study. NMS and EM report grants from Health ResearchTx, LLC (HRTX) reports grant from NIH during the conduct of the study. KNT, CS, and EKL report grant from NIH during the conduct of the study. PW reports grant from Agency for Healthcare Research and Quality during the conduct of the study.

Copyright Notice

Rees Lee is a military service member. This work was prepared as part of his official duties. Title 17 U.S.C. 105 provides that “Copyright protection under this title is not available for any work of the United States Government.” Title 17 U.S.C. 101 defines a United States Government work as a work prepared by a military service member or employee of the United States Government as part of that person's official duties.

Additional information

Funding

This work was supported by Agency for Healthcare Research and Quality grants (R01HS 022093 to PW and R01HS 019669 to TVH), and National Institute of Allergy and Infectious Diseases (K24 AI 077930 to TVH), National Heart, lung and Blood institute (T32 5T32HL087738 to KNT). The funding source did not play a role in the development of the study and the manuscript.