Optimal anti-TNF adherence threshold higher than usual targets

Last Updated: 2017-12-21

By Will Boggs MD

NEW YORK (Reuters Health) - For patients with inflammatory bowel disease (IBD), the optimal adherence to subcutaneous anti-TNF (tumor necrosis factor) treatment exceeds 85%, well above the 80% target in most clinical trials.

"We found that very small delays (4 days every 4 weeks on average) in medication refills was associated with a higher risk of hospitalization or new steroid use," Dr. Shail M. Govani from University of Michigan in Ann Arbor told Reuters Health by email.

Intermittent (nonadherent) anti-TNF treatment is a significant predictor of the development of antibodies to the medication, but little is known about what level of adherence is necessary to avoid flares associated with steroid use and hospitalization. Until now, possession of medication for >80% of the intended time of use has been considered an acceptable target.

Using data from the Truven Health MarketScan Commercial Claims and Encounters database, Dr. Govani's team sought to identify an optimal adherence threshold for these medications to prevent important clinical outcomes.

They used a medication possession ratio (MPR) - calculated as the sum of the days of medication supplied, divided by the sum of the days in the total refill intervals - to assess anti-TNF adherence, according to the December 12 online report in the American Journal of Gastroenterology.

Among patients taking adalimumab, an MPR cutoff of 86% best distinguished nonadherent from adherent patients in terms of hospitalization or new steroid prescription outcomes. Adherent patients were 25% less likely than nonadherent patients to be hospitalized or to be given a new steroid prescription, after adjustment for other factors.

Similarly, for patients taking certolizumab, an MPR cutoff of 87% best distinguished nonadherent from adherent patients, with adherent patients being 46% less likely to require hospitalization or a new steroid prescription.

These adherence measures, as Dr. Govani mentioned, equate to missing only 4 days of medication in a 28-day cycle.

"I think these data should be used to advocate for the removal of barriers which lead to delays for these medications," Dr. Govani said. "These barriers include yearly insurance re-authorizations for the medications."

"I (also) use these data to remind our patients of the importance of taking these medications on time and planning for possible delays which are inevitable in day-to-day life," he said. "I have encouraged patients to set alarms/reminders on their phones to ensure their medications are taken on time."

"Future work on the most effective interventions targeted to high-risk patients taking these medications who fall below this level of adherence is necessary," the researchers note.

SOURCE: http://go.nature.com/2CVlFlL

Am J Gastroenterol 2017.