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Capture-recapture analysis of ascertainment by active surveillance in the British Congenital Cataract Study
1Department of Epidemiology and Public Health, Institute of Child Health/Great Ormond Street Hospital, London, United Kingdom.
Purpose:
Active surveillance has not been widely used in ophthalmologic research. The use of capture-recapture analysis to determine completeness of case ascertainment by active surveillance in a national study of congenital cataract is reported.
Methods:
In 1 year in the United Kingdom, all incident diagnoses of congenital and infantile cataract were notified through independent ophthalmic and pediatric active surveillance schemes. Two-source capture-recapture analysis was applied to assess the level of ascertainment of infants (age < or = 12 months) by these two schemes.
Results:
In a 12-month period, 161 infants with newly diagnosed congenital or infantile cataract were notified. Overall ascertainment was estimated to be 92% complete and was higher in the ophthalmic (85%) than in the pediatric (45%) scheme. Comparison with the number of cases expected, from disease frequency reported in existing national congenital anomaly notification systems, suggests previous underascertainment of congenital cataract in such passive reporting systems.
Conclusions:
This study shows the effectiveness of two-source active surveillance in identifying a nationally representative cohort that will provide better information about this disorder than has been available from sources of routinely collected data.