How Patient Distance From the Pharmacy Influences Asthma Adherence

The distance between a patient and their pharmacy may impact disease management in asthma, according to a new study.

In an assessment of the asthma medication history and residential zip codes of 519 patients to visit Southern Illinois University primary care clinics throughout 2014, investigators found disparities in extent of management dependent on their location. The finding is of particular note to regions including the observed Springfield, IL, where the rate of asthma among adults (10.3%) is greater than both the state (9.1%) and national (8.3%) averages, study coauthor Miathili Deshpande, PhD, said.

Deshpande, assistant professor in the Department of Pharmacy Practice at Southern Illinois University, Edwardsville, noted that due to the notable burden of asthma in Springfield, the investigators found it important to “understand how management of asthma varies by geography and if proximity of healthcare services contribute to poor management.”

Investigators categorized subjects as “intermittent asthmatics” if they were prescribed a rescue inhaler and “persistent asthmatics” if they were prescribed both a rescue and controller medication.

National Heart, Lung, and Blood Institute Guidelines for the diagnosis and management of asthma state that controller medications, such as inhaled corticosteroids (ICS), long acting beta antagonists (LABA), ICS+LABA combinations and leukotriene antagonists are recommended for persistent asthma. Short acting beta antagonists (SABA) and short acting muscarinic antagonists (SAMA) are recommended for use as rescue medications, which provide fast acting relieve of asthma symptoms.

Previous studies have shown that underuse of controller medications and overuse of rescue medications is a recurrent problem among asthmatics.

Study results showed that patients with inappropriate medication use lived farther from their preferred pharmacy than those with appropriate use (median distance 3.02 miles and 1.96 miles, respectively; P = .01). Almost 17% of older adults (65 years or older) overused their rescue inhaler, while patients 18-34 (64.2%), 35-49 (57.3%), and 50-64 (48.2%) years old used their controller medications insufficiently. Former smokers with persistent asthma also had a higher chance of inadequate asthma management than those who never smoked (OR = 1.77; 95% CI: 1.00 - 3.14).

Due to small sample size, the associations between the distance of a patient’s preferred pharmacy and improperly managed asthma were not maintained after adjusting for patient characteristics and clinic type. However, Deshpande said that transportation barriers and proximity might affect whether or not individuals are able to fill a rescue inhaler.

“Previous research has suggested that 'pharmacy deserts' (areas with a low percentage of pharmacies) may affect medication access which is a potential upstream factor contributing to inappropriate management,” said Deshpande.

Other limitations include the labeling of patients as inadequate medication users based on prescribing history and assuming preferred pharmacy based on what was noted in their chart (it was not definitively confirmed if patients actually filled their prescriptions at preferred pharmacy).

“Further study, with an appropriately large data set, should explore the relationship between geography and asthma medication use using more rigorous spatial methods where we’re able to perform analysis to better identify clusters of areas with poor asthma management,” Deshpande said.

The study, “Spatial analysis of disparities in asthma treatment among adult asthmatics”, was published online in Research in Social and Administrative Pharmacy.