Background: Patients with chronic obstructive pulmonary disease (COPD) have raised serum levels of C reactive protein (CRP). This may be related directly to COPD and its associated systemic inflammation or secondary to other factors such as concomitant ischaemic heart disease (IHD) or smoking status. The aim of this study was to evaluate IHD and smoking as potential causes of raised CRP levels in COPD and to test the association between inhaled corticosteroid (ICS) use and serum CRP levels. Methods: Cross sectional analyses comparing cohorts of 88 patients with COPD, 33 smokers (S), and 38 non-smoker (NS) controls were performed. Clinical assessments included a complete medical history, pulmonary function, 6 minute walk test (6MWT), cardiopulmonary exercise test, and high sensitivity serum CRP measurements. Results: Serum CRP levels were significantly higher in patients with COPD (5.03 (1.51) mg/l) than in controls (adjusted odds ratio 9.51; 95% confidence interval 2.97 to 30.45) but were similar in the two control groups (S: 2.02 (1.04) mg/l; NS: 2.24 (1.04) mg/l). There was no clinical or exercise evidence of unstable IHD in any of the subjects. CRP levels were lower in COPD patients treated with ICS than in those not treated (3.7 (3.0) mg/l v 6.3 (3.6) mg/l); this association was confirmed in an adjusted regression model (p,0.05). Conclusion: CRP levels are raised in COPD patients without clinically relevant IHD and independent of cigarette smoking, and reduced in patients with COPD using ICS. CRP may be a systemic marker of the inflammatory process that occurs in patients with COPD.

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.

To cite this article: Feudjo-Tepie MA, Robinson NJ, Bennett D. Prevalence of diagnosed chronic immune thrombocytopenic purpura in the US: analysis of a large US claim database: a rebuttal. J Thromb Haemost 2008; 6: 711-2. See also Segal JB, Powe NR. Prevalence of immune thrombocytopenia: analyses of administrative data. J Thromb Haemost 2006; 4: 2377-2383; Segal JB, Powe NR. Prevalence of diagnosed chronic immune thrombocytopenic purpura in the US: analysis of a large US claim database: reply to a rebuttal. This issue, pp 713. We read with interest the paper by Segal and Powe [1] on the prevalence of immune thrombocytopenic purpura (ITP). ITP is a disease caused by inadequate platelet production, as well as increased platelet destruction, and is traditionally categorized into acute and chronic forms. For the latter, thrombocytopenia needs to be present for at least 6 months [2]. In this paper, Segal and Powe refer to ITP as immune (rather than idiopathic) thrombocytopenia purpura. There is relatively little epidemiological evidence on chronic ITP, and its prevalence in the US is poorly documented. The paper by Segal and Powe is one of the first population-based studies of prevalence of ITP in the US that provides an estimate of chronic ITP (albeit informal). However, as the authors noted, there were some limitations in their study. Most of these were related to the limitations in the data source. In the analysis presented here, we aimed to estimate the diagnosed prevalence of ÔchronicÕ ITP in the US in 2005, using a large US claims data base. In particular, our analysis overcomes some of the main limitations in Segal and PoweÕs paper. (i) Segal and Powe used only one calendar year (2002) of data and identified potentially chronic ITP patients as those with at least two ITP ICD-9 codes (287.3), which were separated by at least 6 months. Therefore, a patient whose first ITP ICD-9 code occurred in the second half of 2002 had no chance of presenting a second code within the 2002 calendar year. Hence, as the authors pointed out, their estimation of the prevalence of ÔchronicÕ ITP in all people under 65 years (4.5 per 100 000) may be a considerable underestimate. (ii) Segal and PoweÕs estimation only includes patients under 65 years old. The increased risk of ITP with age is well documented [3-5] and excluding patients over 64 years of age would lead to an underestimate. We analyzed the Integrated Healthcare Information System (IHCIS) database, one of the largest US health care managed databases, fully de-identified, with over 70 million patients from more than 45 health plans. It covers 7 out of 10 census regions and contains patient demographics, age, gender and morbidity. Our patient population consisted of patients enrolled to one of the health plans before or any time between 2002 and 2006 with a continuous enrollment throughout the year 2004. Chronic ITP cases were defined as patients with at least two diagnoses (ICD-9 code 287.3) for primary thrombocytopenia separated by at least 6 months between 2002 and 2006....