Determinants of persistence with weekly bisphosphonates in patients with osteoporosis

To evaluate the relationship between the persistent acquisition of bisphosphonate (BP) osteoporosis (OP) medication and the following factors: BP prescribed; whether BP was first used to replace another non-BP drug for OP; patient age; type of drug coverage; specialty of initial prescribing physician; and number and type of comorbid diseases.

Data were acquired from a large Canadian public and private claims database, which included information on all prescriptions filled, including drug preparation, dose, dosing schedule, number of tablets dispensed, and the date of dispensing. A total of 62,897 female patients who had initiated weekly BP therapy (risedronate 35 mg once weekly or alendronate 70 mg once weekly) for OP between January 1, 2003, and February 28, 2006 were analyzed, each for 12 months. Persistence rates were determined for 6 and 12 months post initial prescription. Regression models were used to assess the influence of various patient, physician, and drug factors.

Persistence of BP declined over the first year of BP prescription, to between 60% and 74% by 6 months, and between 37% and 59% by 12 months, depending upon a variety of factors. The factors that most adversely influenced BP persistence were patient age (< 65 vs > or = 65; p < 0.0001); the type of drug coverage (public vs private; p < 0.0001); prescribing physician specialty (GP vs specialist; p < 0.0001); and number and type of comorbid illnesses (p < 0.01).

Persistence to BP declined significantly over one year. Healthcare practitioners should take note of several factors when counselling patients taking BP for OP.