Since then, the Canadian tenth revision (ICD-10-CA) codes have been used. Measuring persistence with therapy We determined persistence with therapy using ODB (pharmacy claims) data. ODB data include the days supplied and thus we can calculate

when a patient is expected to refill their prescription. We defined persistence as continuous treatment without an interruption (gap) exceeding 60 days (Fig. 1). In a secondary analysis, we extended the permissible gap length to 120 days. These gap small molecule library screening lengths are consistent and comparable with prior research on persistence with osteoporosis pharmacotherapy [20–23]. When calculating persistence, overlap of the same drug and regimen was additive; however, a switch between agents or from daily to weekly dosing of the same drug was considered continuous use with no overlap granted. Values for missing days supplied selleck kinase inhibitor were imputed prior to 1997 when this field was not reported in the ODB database; this included 13 patients dispensed alendronate (24 dispensing CX-5461 manufacturer records), and all patients dispensed cyclical etidronate prior

to 1997. We imputed a 60-day supply for alendronate—the median number of days supply for alendronate from 1997 to 1999. A 90-day supply was imputed for cyclical etidronate since it is dispensed as 14 days of active drug plus 76 days of calcium supplements. Fig. 1 Defining persistence with therapy (adapted from Cadarette et al. [33]). Persistence with therapy after index was defined as continuous treatment without a gap >60 days (primary analysis) and >120 days (secondary analysis). Theoretical end of treatment Ribonucleotide reductase must have occurred within the follow-up interval under investigation; however, pharmacy data after the theoretical treatment end date were used to identify whether or not an extended gap was relevant to define non-persistence. *If the gap length between prescriptions was ≤60 days, then the patient was assumed to have persisted with therapy. **Example when a patient

reinitiates therapy after an extended gap. Some patients never reinitiate treatment and are defined in Table 2 as having discontinued therapy. Rx = Prescription Statistical analysis We compared the characteristics (age, sex, bisphosphonate at index, prior BMD testing, and fracture history) of new users across four time periods: April 1996–March 2000, April 2000–March 2003, April 2003–March 2006, and April 2006–March 2008. We then examined persistence with therapy and number of extended gaps (primary analysis gap length >60 days and secondary analysis gap length >120 days) between prescriptions according to follow-up periods ranging from 1 to 9 years after treatment initiation. Only those persons with complete follow-up information were included in each respective follow-up period, and therefore patients who died within the observation period were excluded from respective analyses.