BACKGROUND AND OBJECTIVES: In literature, different methods of calculating persistence are used. In this study, the effect of using these different methods on persistence and the association of patients characteristics and persistence are assessed. METHODS: The PHARMO record linkage system was used to calculate persistence with antihypertensive drugs for a cohort of 14,466 new users of antihypertensives. Three different types of methods were used to define the maximum gap allowed between two prescriptions that a patient may have to be defined as a continuous user, one based on a defined number of days (varying from 9-365 days), the second based on the duration of the last prescription (varying from 0.1-4 times the duration), the third based on a combination of both methods, whichever leads to the lowest number of days. RESULTS: Refill persistence varied between 19.7-86.4% (method 1), between 27.9-90.2% (method 2), and between 19.7-86.4% (method 3). Furthermore, patient characteristics associated with persistence differed between and within the three different methods. CONCLUSION: The method used and the variation within a method influenced both persistence and the association between patient characteristics and persistence. Results of persistence studies are highly influenced by the researchers' method of the maximum allowed treatment gap.
BACKGROUND AND OBJECTIVES: In literature, different methods of calculating persistence are used. In this study, the effect of using these different methods on persistence and the association of patients characteristics and persistence are assessed. METHODS: The PHARMO record linkage system was used to calculate persistence with antihypertensive drugs for a cohort of 14,466 new users of antihypertensives. Three different types of methods were used to define the maximum gap allowed between two prescriptions that a patient may have to be defined as a continuous user, one based on a defined number of days (varying from 9-365 days), the second based on the duration of the last prescription (varying from 0.1-4 times the duration), the third based on a combination of both methods, whichever leads to the lowest number of days. RESULTS: Refill persistence varied between 19.7-86.4% (method 1), between 27.9-90.2% (method 2), and between 19.7-86.4% (method 3). Furthermore, patient characteristics associated with persistence differed between and within the three different methods. CONCLUSION: The method used and the variation within a method influenced both persistence and the association between patient characteristics and persistence. Results of persistence studies are highly influenced by the researchers' method of the maximum allowed treatment gap.
Authors: Boris L G van Wijk; William H Shrank; Olaf H Klungel; Sebastian Schneeweiss; M Alan Brookhart; Jerry Avorn Journal: J Hypertens Date: 2008-01 Impact factor: 4.844
Authors: Miriam Qvarnström; Thomas Kahan; Helle Kieler; Lena Brandt; Jan Hasselström; Kristina Bengtsson Boström; Karin Manhem; Per Hjerpe; Björn Wettermark Journal: Eur J Clin Pharmacol Date: 2013-07-16 Impact factor: 2.953
Authors: Maurits E L Arbouw; Kris L L Movig; Henk-Jan Guchelaar; Petra J E Poels; Jeroen P P van Vugt; Cees Neef; Toine C G Egberts Journal: Eur J Clin Pharmacol Date: 2008-07-15 Impact factor: 2.953