A capture-recapture model to estimate prevalence of XXXX born in Scotland with @entity735 .

@entity1 @entity154 @entity4353 @entity17347 @entity735 @entity4643
BACKGROUND: @entity4353 , @entity17347 and @entity4643 (MAC) are closely related @entity735 that have caused public concern in the UK following media reports of apparent clusters of cases. An extensive search was carried out to identify potential cases, and diagnoses were confirmed by ophthalmological review. Despite this effort, it was recognised that some cases would remain unidentified. Capture-recapture methods could improve the accuracy of the study's birth prevalence estimate. METHODS: A register of all @entity1 born with the @entity735 of MAC in Scotland (1981-96) was compiled. This identified 188 cases from eight national ascertainment sources. The methods described by Hook and Regal were used to determine possible estimates for each source. A log-linear method of capture-recapture was used to fit a model to the number of @entity1 identified by the different combinations of the eight national sources, and the individual sources were included in the model as main effects. RESULTS: Maximum-likelihood estimates were calculated for tables of captured/not captured by one source versus any other source. The estimated number of unobserved cases for the most complete source, the register of @entity154 for Scotland, and the seven others combined is 78 (95% CI 53-115). Estimates calculated from two different log-linear models of the numbers of cases unobserved by all sources were 61 (95% CI 43-86) and 175 (95% CI 106-287). An external check with an independent @entity154 register in one region, which is known to have high completeness, gave an estimate of 120. The study found a birth prevalence of MAC in Scotland of 1.9/10000, based on total live births during the study period. The capture-recapture analysis suggests that the true birth prevalence lies between 2.4/10 000 and 3.5/10000. DISCUSSION: Our experience shows that, even with multiple sources of ascertainment and considerable resources directed at case identification, a considerable level of under-ascertainment of congenital @entity735 still results, and suggests that the use of capture-recapture analysis would be a useful addition to @entity154 registers for needs assessment, disease-burden estimates and health-service planning.
