[Adherence with daily and weekly administration of oral bisphosphonates for osteoporosis treatment]

Bisphosphonates provide efficacious treatment for osteoporosis. However, side effects often lead to patients discontinuing this treatment. This study analyses differences in adherence (including acceptance, persistence and compliance) between daily (ALD-D) and weekly (ALD-W) administration of alendronate among German patients with osteoporosis.

Prescription claims data of two random groups of subjects (144 patients each) taking ALD-D and ALD-W, respectively, were observed for 12 months after starting the given prescription. Termination was defined as the moment when the last prescription had been used up. The percentage of patients continuing the drug treatment after the first prescription was used as a measure for acceptance. Compliance was measured by the medication possession ratio (MPR), namely the percentage of days on which the patient was supplied with the medication. An MPR > 80% is therapeutically relevant because the risk of fractures is significantly reduced.

31.3% (ALD-W) vs. 45.8% (ALD-D) of patients discontinued therapy after one prescription. 53.5% (ALD-W) vs. 72.2% (ALD-D) of patients discontinued therapy throughout the year. The proportion of those who discontinued the treatment was significantly higher with daily administration (p=0.0035). Mean time until discontinuation was 220 days (ALD-W) vs. 169 days (ALD-D). Mean compliance among any patients was 51.7% (ALD-W) vs. 37.7% (ALD-D); Only 30.6% (ALD-W) vs. 19.2% (ALD-D) (p=0,0295) of patients reached a therapeutically relevant compliance level.

A large proportion of patients discontinued treatment with bisphosphonates, a majority of discontinuing patients not even refilling their first prescription. Adherence, although enhanced by less frequent dosing, was suboptimal in all of its aspects, i.e. acceptance, persistence and compliance. There is a need for treatment strategies to increase adherence.