Clinical Economics of Asthma Controller Medication: Adherence & Outcomes

By Sudhanshu Bansal

4 April 2018

Practical Analytic Approaches to Healthcare Challenges

Asthma is a lifelong disease. In addition to limiting a person’s quality of life, medically it is also associated with significant healthcare utilization and costs.[i] According to a survey in 2015, there were 5.9 million physician office visits and 2.0 million Emergency Department visits in the US because of asthma.[ii] [iii] The Centers for Disease Control and Prevention (CDC) estimated that in 2007 asthma alone cost the U.S. about $56 billion in medical costs, lost school and work days, and early deaths.

Good adherence to long-term asthma controller medications, defined as 50% or greater, has been shown to be associated with reduced acute asthma exacerbations in patients with persistent asthma and is one of the key outcome measurements for programs focused on improving persistent asthma management. Despite these facts, actual adherence is only about 30 to 40%.[iv] [v] One likely barrier to achieving higher asthma controller medication adherence is cost. Generic medications, which are usually less expensive than branded medications, were found to have better overall adherence rates.[vi]

To explore asthma controller medication adherence rates, treatment outcomes, and any potential association with branded or generic drugs, Milliman conducted a focused analysis using MedInsight’s healthcare analytic platform on a large database containing claims for over 3.9 million Medicaid, Medicare Advantage and commercial members. We compared the incidence of acute asthma exacerbations and status asthmaticus events among asthma patients (defined as having intermittent or persistent asthma) who were exclusively on branded asthma controller medications to patients who were exclusively on generic asthma controller medications. We also researched the proportion of generic and branded asthma controller medications and utilization patterns in patients that achieved a high adherence rate. We defined our goal for high adherence as 80% or greater for the proportion of days covered (PDC) with asthma controller medications for patients under treatment for more than three months.


  • Asthmatic patients were prescribed 52 types of asthma long-term controller medication drug compositions within the study period. This compares with a total of 69 drug compositions considered to be asthma long-term controller medications (HEDIS AMR-A table).[vii]
  • Forty-two out of the 52 prescribed compositions were branded compositions.
  • Twenty-two percent of asthma patients using generic controller medications exclusively had high adherence rates (80% or higher) compared with 14% of asthma patients who were using branded controller medications exclusively.
  • Asthma patients using generic controller medications exclusively had much lower rates for acute exacerbations and status asthmaticus (34%) than asthma patients using branded controller medications exclusively (62%). Both groups had high adherence rates of over 80%.
  • Comparison

  • We also found that patients using generic controller medications exclusively and having adherence rates greater than 80% had 24% lower Emergency Department visits and 32% lower inpatient admissions per thousand member months compared with patients using branded controller medications exclusively.
  • Comparison

    Our observations were based on limited administrative claims data; however, the results are in line with the analysis presented by association for accessible medicines depicting higher compliance among patients on generic drugs and other While potential reasons for this finding such as demographic differences or formulary composition were not investigated, the most likely reason for this observation is differences in asthma severity between the population using generic controller medications and the population using branded controller medications.


    [i] American Academy of Allergy, Asthma and Immunology. Allergy and Asthma Drug Guide.

    [ii] Centers for Disease Control and Prevention. National Center for Health Statistics. Last updated: March, 2017. Available at:

    [iii] National Ambulatory Medical Care Survey: 2015 State and National Summary Tables. Available at:

    [iv] Asthma Controller Medication Adherence, Risk of Exacerbation, and Use of Rescue Agents Among Texas Medicaid Patients with Persistent Asthma. Published: 2015.

    [v] Mika J. Mäkelä, Vibeke Backer, Morten Hedegaard, Kjell Larsson, Adherence to inhaled therapies, health outcomes and costs in patients with asthma and COPD, Respiratory Medicine, Volume 107, Issue 10, 2013, pages 1481–1490, ISSN 0954-6111. Available at:

    [vi] Generic Drug Access & Savings in the U.S. Association for Accessible Medicines (AAM). 2017 Report. Available at:

    [vii] HEDIS 2017 Volume 2 NDC Code List. Available at:

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