ORLANDO – Men may be more adherent than women are in their use of asthma controller medications, but adherence overall is poor, according to an analysis of claims from a large database.
Older adults were also more adherent than were younger adults in the retrospective cohort study, which included medical and pharmacy claims for 145,950 patients aged 18-65 years who were seen from January 2006 to December 2008.
To be included, patients included had to have 12 months or more of continuous medical and pharmacy eligibility following the index date (6 months after first medical claim for asthma), said Leslie J. Hinyard, Ph.D. at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
Mean age at enrollment was 41 years for the 53,532 men, and 43 years for the 92,418 women. Adherence was defined by the Medication Possession Ratio (MPR), calculated as the number of days for which the medication is supplied divided by the number of days from first fill through the end of study eligibility.
Overall adherence, stratified by gender, ranged from a low MPR of 0.246 for inhaled corticosteroid use among women to a high of 0.597 for omalizumab use in women.
"I was actually surprised by how poor adherence was across the board. It’s actually consistent with what you find throughout the literature; but the adherence to what should be medicines taken daily over a long period of time is rather poor," said Dr. Hinyard, who is with the St. Louis University Center for Outcomes Research and also the university’s department of internal medicine, division of allergy.
Men had significantly greater adherence than did women for inhaled corticosteroid (MPR, 0.259 vs. 0.246), long-acting beta-agonists (0.384 vs. 0.345), combinations of the two (0.388 vs. 0.352), and for mast cell–stabilizing agents (0.238 vs. 0.205). On the other hand, women were significantly more adherent than men were for leukotriene modifiers (0.499 vs. 0.472).
"I was intrigued by the fact that, across the board, men seemed to have slightly higher adherence than women, except for leukotriene modifiers, which are pills. The rest are all inhaled," Dr. Hinyard said in an interview.
She noted that the explanation could be that women are more accustomed than are men to taking pills, rather than that men are more apt to use inhalers. However, she emphasized, "I’m completely speculating."
There was no statistically significant difference between men and women for oral steroid use, monoclonal antibodies, or theophylline.
Examined by age tertiles of 18-34 years, 35-49 years, and 50-65 years, there was a positive linear association between age and adherence for all drug categories except for chronic oral steroids.
For example, with inhaled corticosteroids, 45% of those aged 50-65 years fell into the top tertile for adherence, compared with 16% of the 18- to 34-year-olds. "Older adults were more adherent, especially compared to the younger adults," she noted.
"We need to understand if there’s a minimal threshold for adherence that will keep people from having exacerbations," Dr. Hinyard said. "We’re never going to get perfect adherence, but perhaps we can set a more realistic goal for people to strive for."
Dr. Hinyard had no relevant disclosures.