Such evaluation of persistence provides insight into the duration of treatment supply [11, 30, 31]. The treatment

episode was defined as the period of time in which the patient continuously used the specific drug. If the gap between consecutive dispensing dates was more than 6 months, the last prescription of the drug before this gap was considered as the last prescription. The treatment period lasts from start date till end date of this last prescription using the therapy duration of this last prescription as recorded by the pharmacy. Each patient was judged during 365 days selleck as being either persistent (still on medication on drug of start) or non-persistent (no longer using this drug of start). Persistence after 1 year was calculated and used to correlate with factors that could influence 1-year persistence. Patients who stopped the initial drug during the first half year were followed during an additional 18 months. For the analysis of 12 months’ persistence, data were obtained from the LRx database between September 2006 and October 2008. All consecutive patients starting selleck screening library one of the available oral osteoporosis drugs between March and May 2007 and not receiving prescriptions of that particular drug during at least 6 months previous to the start were included. This timing selection

allowed in all patients to include a 6-month follow-up (trailing) period and a 6-month lookback period (Fig. 1). Fig. 1 Analysis of 12 months’ persistence In this analysis, we started with a total of 171,293 patients having any osteoporosis medication

of which 168,749 received oral medication. Most patients (n = 99,148) received their first prescription in our prescription database in the lookback period or during reporting and trailing period (n = 60,975), which results in 8,626 starters for the analysis of persistence. Moving to another address (e.g., nursing home) or death during follow-up could have biased the persistence results. Therefore, persistence was also separately analyzed in patients who also continued other than osteoporosis medications at the end of the period. Determinants Isotretinoin of persistence In order to explore factors that could be related to 12-month persistence, three groups of possible determinants were recorded. First, we used the patient-depending information like age, gender, sex, and rurality of the patients’ pharmacy. Second, we studied the co-medications at start and in the trailing period. Third, we added the specialty of the prescriber who prescribed the first osteoporosis drug. Co-medications were analyzed for ten treatment segments, each corresponding with one or more therapeutic areas. Some treatment classes had a relation to osteoporosis (e.g., calcium, vitamin D, and glucocorticosteroids) and others were chronic medication classes for other diseases (e.g.