Asthma Medication Ratio Reliably Predicted Exacerbations in Children on Medicaid

Nearly 10% of pediatric patients with asthma with Medicaid public health insurance had a high-risk asthma medication ratio (AMR) during any given time period, which reliably predicted severe acute exacerbations within 3 months. Thus, such high-risk patients have almost double the odds of a severe episode compared with other children with asthma with lower-risk AMRs, according to study results published in the Journal of Asthma.

Given the prevalence of childhood asthma, the potential for severe exacerbations and the tendency for children of lower socioeconomic status to have poorer outcomes, possibly as a result of lower medication adherence, an accurate and efficient tool for identifying high-risk patients is desperately needed. The AMR offers near real-time risk assessment that can be utilized to allow targeted interventions directed at the highest-risk patients, potentially narrowing the outcome disparity seen between patients insured publicly vs commercially.

A longitudinal retrospective analysis utilized 2013 to 2014 Truven Health Medicaid pharmacy and medical claims data to enroll 214,452 patients with asthma (mean age, 7.8 years; 59% boys) aged 2 to 17 years who had ≥1 claim for an inhaled corticosteroid (ICS) or ICS/long-acting β₂-agonist (LABA). The AMR — defined as the number of controller medication claims / (number of controller medication claims plus number of rescue medication claims) — was calculated for rolling 3-month periods and served as the independent variable. The dependent variable and primary outcome was having or not having any emergency department (ED) visit or hospitalization for an asthma exacerbation in a given period.

The percentage of individuals classified as high-risk (AMR <.5), low-risk (AMR ≥.5) and no medication claims (without any asthma medication) in each time period was reported, and the likelihood of having an acute exacerbation within 3 months based on the primary outcome was calculated. Simple logistic regression analysis was employed to assess the association between AMR classification and subsequent ED visits or hospitalizations for asthma, reported as odds ratios (ORs) and 95% CIs.

The majority of patients (85%) had ICS prescribed as their index controller medication, with the remainder (15%) prescribed ICS/LABA. In comparing index medications, patients using ICS/LABA vs ICS alone had more high-risk AMRs (12% vs 8.5%) and fewer no-medication claims (37% vs 54%). A total of 16.6% of all patients had ≥1 ED visit or hospitalization due to asthma complications. The population level frequency of such events was highest in the high-risk AMR group (25.0%), lowest in the no-medication claims group (13.9%), with the low-risk AMR group falling in the middle (18.1%), demonstrating significant between-group differences (P <.0001).

In any given 3-month period, 8% to 9% of the cohort on average was classified as having a high-risk AMR, a mean of 51% were categorized as no-medication claims, and an average of approximately 40% was rated as having a low-risk AMR. Regression analysis revealed that high-risk AMR patients were almost twice as likely as low-risk or no-medication claims individuals to have had an asthma-related ED visit or hospitalization within 3 months (ORs, 1.7-1.9; 95% CIs, 1.6-2.0).

Study limitations included the use of administrative claims data, inability to determine prescription writing from the data used, exclusion of any medications not paid for by insurance, lack of geographical information, and use of a nonstandard method to identify eligible participants.

“These findings further support the rolling 3-month AMR as an appropriate method for identifying children at high risk for imminent exacerbation regardless of public or private insurance status,” noted the investigators. They recommended that future research continue to explore differences in AMR classification and acute exacerbation rates between publicly- and privately-insured individuals.

Disclosures: This research was supported by the South Carolina Clinical and Translational Research (SCTR) Institute, with an academic home at the Medical University of South Carolina, National Institutes of Health/National Center for Advancing Translational Sciences (grants KL2 TR001452 and UL1 TR001450) and the Doris Duke Charitable Foundation (grant 2015209).

The authors report no conflicts of interest.

Reference

Andrews AL Brinton DL, Simpson KN, Simpson AN. A longitudinal examination of the asthma medication ratio in children with medicaid published online July 17, 2019. J Asthma. doi:10.1080/02770903.2019.1640727