NASHVILLE, TENN. — Women with postmenopausal osteoporosis are no more likely to adhere to bisphosphonate therapy with weekly dosing than with daily dosing, according to data presented in a poster at the annual meeting of the American Society for Bone and Mineral Research.
In a retrospective study of 12,538 women with postmenopausal osteoporosis, risk of adherence failure did not differ between patients receiving weekly versus daily bisphosphonate therapy, according to Derek Weycker, Ph.D., of Policy Analysis Inc. in Brookline, Mass., and colleagues.
The researchers reviewed integrated medical and outpatient pharmacy claims from 1998 to 2003 for women aged 45 years and older with postmenopausal osteoporosis from 30 U.S. health plans.
Women were said to have postmenopausal osteoporosis if they had one or more medical claims with a corresponding diagnosis code. They also had no evidence of secondary causes of osteoporosis.
Adherence was assessed daily from the date of therapy initiation through the date of a switch to another antiosteoporosis drug or formulation, date they left the plan, or Dec. 31, 2003—whichever came first.
Within 6 months of initiating therapy, 57% of the 9,117 women on weekly therapy and 62% of the 3,421 women on daily therapy were considered to have adherence failure. At 1 year, 66% of those on weekly therapy and 71% of those on daily therapy had adherence failure. At 2.5 years, the rates were 80% for weekly therapy and 82% for daily therapy.
Risk of failure was higher among women aged 65 years and older but lower in those with a fracture history. The researchers did not assess adherence for specific drugs.
The research was funded by Amgen Inc., which is currently investigating a fully monoclonal antibody for osteoporosis.