Identifying families with limited English proficiency using a capture-recapture approach.

Background and Objective: Health providers need reliable estimates of the number of families with limited English proficiency (LEP) to assess language need and language service provision. Hospitals often lack reliable language screening tools and fail to provide interpretation for LEP families. The objective of this study was to develop a simple audit tool to more accurately identify LEP patients and families. Methods: We conducted a cross-sectional analysis of a retrospective cohort of patients admitted to a large pediatric hospital between July 1 and December 31, 2009. We used a “capture-recapture” approach to develop a simple audit tool to measure language screening, determine the rate of language interpretation, and estimate the number of LEP families. The captures were based on 2 independent sources: (1) language need identified at registration and (2) request for interpretation during hospital admission. Assuming a closed population, we estimated the number of LEP families missed by both captures. Results: During the study period, 6887 patients were admitted for care. There were 948 LEP families identified at registration and 847 families received interpretation at least once during hospital admission. We determined that the “ascertainment corrected” number of LEP families was 1031 (95% confidence interval: 1022–1040). The number of patients who had been “missed” by both methods was 15 (95% confidence interval: 7–24). Only 76% of LEP patients were identified in both data sources. Conclusions: A simple language audit tool can be used to determine language need, rates of interpretation, and unmet demand for language services, even when both sources of data are incomplete.