Estimation of the Period Prevalence of Inflammatory Bowel Disease Among Nine Health Plans Using Computerized Diagnoses and Outpatient Pharmacy Dispensings

Harvard University, Cambridge, Massachusetts, United States
Inflammatory Bowel Diseases (Impact Factor: 4.46). 04/2007; 13(4):451-61. DOI: 10.1002/ibd.20021
Source: PubMed


There are few contemporary estimates of prevalence rates for inflammatory bowel disease (IBD) in diverse North American communities.
We estimated the period prevalence of IBD for January 1, 1999, through June 30, 2001, among 1.8 million randomly sampled members of nine integrated healthcare organizations in the US using computerized diagnoses and outpatient pharmaceutical dispensing. We also assessed the positive predictive value (PPV) and sensitivities of 1) the case-finding algorithm, and 2) the 30-month sampling period using medical chart review and linkage to a 78-month dataset, respectively.
The PPV of the case-finding algorithm was 81% (95% confidence interval [CI], 78-87) and 84% (95% CI, 79-89) in two different organizations. In both, the sensitivity of the optimal algorithm, compared with the most inclusive, exceeded 90%. The sensitivity of the 30-month sampling period compared with 78 months was 61% (95% CI, 57-64) in one organization. Applying a slightly more sensitive case-finding algorithm, the average period prevalence of IBD across the nine organizations, standardized to the age- and gender-distribution of the US population, 2000 census, was 388 cases (95% CI, 378-397) per 100,000 persons (range 209-784 per 100,000; average follow-up 26 months). The prevalence of Crohn's disease, ulcerative colitis, and unspecified IBD was 129, 191, and 69 per 100,000, respectively.
The observed average prevalence was similar to prevalence proportions reported for other North American populations (369-408 per 100,000). Additional research is needed to understand differences in the occurrence of IBD among diverse populations as well as practice variation in diagnosis and treatment of IBD.

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    • "Epidemiological studies of IBD in the USA are necessary to quantify the public health burden of disease and inform policy regarding the allocation of resources and provision of health services for affected individuals. Because IBD is not a reportable condition in the USA and comprehensive, nationwide registries for IBD surveillance have not been established, published studies on the epidemiology of IBD in the USA [1–6] are limited and primarily include studies which have sampled small, geographically restricted populations. Furthermore, no studies of IBD prevalence have been published using data from the last 5 years and, therefore, current time trends remain unknown. "
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    • "Validation studies for chronic diseases have also been published [16,17]. These generally, though implicitly, are studies of disease prevalence rather than incidence. "
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