BACKGROUND: Bisphosphonates are effective in the prevention and treatment of osteoporosis, yet their use is suboptimal.
OBJECTIVES: To measure bisphosphonate compliance among first-time users and identify factors associated with compliance.
METHODS: We conducted a prospective follow-up of all women aged 45+ in the second largest health management organization in Israel who were prescribed bisphosphonates for the first time. The 4448 women were classified by drug dosage. Persistence and adherence measures of compliance were calculated for each woman over a 1 year period.
RESULTS: Mean bisphosphonate persistence over a year was 216 days, with a mean medication possession ratio of 66%. Women whose medication was changed, whether from weekly to daily or daily to weekly, always had better persistence rates than those who consistently took the original dose. Persistence rates were as follows: 264 days for women who switched back and forth between daily and weekly doses, 229 days for those who switched from daily to weekly, 222 days for those who took the dosage weekly only, 191 days for those who switched to daily dosage, and 167 days for those who took the dosage daily only (P < 0.001). Switchers were also more likely to have adequate adherence rates (MPR > or = 80%): 81.3%, 76.6%, 67.5%, 61.3% and 52.2% respectively (P < 0.001). More than 20% of women stopped taking their medication within the first month. Women with higher supplemental insurance (offering significant discounts for weekly dose medications) had better persistence rates: 221 vs. 208 days (P = 0.03). Younger women and women on national pension insurance had the lowest persistence rates: 204 and 209 days respectively.
CONCLUSIONS: While weekly bisphosphonate takers had better compliance rates, persistence and adherence rates were inadequate for all groups. Changing medication to meet the needs of the patient, discounting weekly medications, and providing follow-up within the first months of prescription may promote compliance.