Abstract Published data on the epidemiology of idiopathic thrombocytopenic purpura (ITP) among adults are very limited. We conducted a study of ITP incidence using the General Practice Research Database in the United Kingdom. From 1992 to 2005, there were 840 cases of ITP among adults considering 21 749 623 person‐years (PYs) of follow‐up, for a crude incidence of 3.9 per 100 000 PYs [95% confidence interval (CI): 3.6, 4.1]. The incidence was higher among women [4.5 per 100 000 PYs (95% CI: 4.2, 4.9)] than men [3.2 per 100 000 PYs (95% CI: 2.8, 3.5)]. Among both women and men, incidence was higher at older ages and in later study years. In a systematic review of previously published literature, incidence of ITP among adults ranged from 1.6 to 2.68 per 100 000 persons per year; prevalence ranged from 9.5 to 23.6 per 100 000 persons. In order to improve the understanding of the disease burden of ITP, future studies should include a clearly defined definition of ITP and focus on well‐described source populations that are geographically and ethnically diverse.
A person experiencing more than one medical condition may have ambiguous clinical presentation. ITP is a serious autoimmune disease with little epidemiological evidence on its burden, risk factors, and comorbidities. Using the United Kingdom general practice research database, we conducted a 14 years population-based case control-type study to explore medical conditions more likely to cooccur with ITP and their temporal relationship in association with ITP. ITP patients were matched to non-ITP on practice, age, gender, and follow-up period. Potential comorbidities were represented by patients' medical information at the preferred term level of the MedDRA international classification. As well as death (OR = 60.0; 95% CI [4.47-806.0]) and known clinical signs and symptoms of ITP, ITP is associated with considerable number of medical conditions. The association between ITP and some of these conditions is apparent both before and after ITP diagnosis. Specific targeted studies can now be setup to reexamine observed associations.
Objective This study aims to describe the switch patterns of osteoporosis medication in postmenopausal women and to explore the impact of switching on persistence. Methods This study used a cohort of postmenopausal women who initiated the first treatment with osteoporosis medication between 1995 and 2008. Selected women had switched at least once to a different frequency or type of osteoporosis medication during follow-up. For each study woman, we identified the first therapy (initial osteoporosis medication), second therapy (medication received at first switch), and, where available, third therapy (medication received at second switch), regardless of how many times she switched during follow-up. Persistence was defined as the number of days from the index date to the end of the last prescription within each episode of use. The Kaplan-Meier method was used to calculate persistence rates at 6 months, 1 year, 3 years, and 5 years. Results Of 20,638 women who switched osteoporosis treatment at least once in the study period, approximately 67% switched once, 21% switched twice, and 12% switched three times or more. Persistence rates for the second therapy were highest (% [95% CI], 46.6 [46.1-47.1], 35.0 [34.5-35.5], 18.8 [18.3-19.3], and 11.4 [10.9-11.7] at 6 mo, 1 y, 3 y, and 5 y, respectively), whereas persistence rates for the first therapy were lowest (% [95% CI], 34.3 [33.9-34.8], 21.6 [21.2-21.9], 5.90 [5.68-6.13], and 1.57 [1.45-1.69], respectively). Conclusions Among women who switch their initial medication, even though switching to the second medication improves persistence during the initial therapy, persistence on the second and subsequent therapies remains suboptimal.
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