Needles in the haystack: Using open-text fields to identify persons with intellectual and developmental disabilities in administrative home care data

Background: Use of administrative health data to study populations of interest is becoming more common. Identifying individuals with intellectual and developmental disabilities (IDD) in existing databases can be challenging due to inconsistent definitions and terminologies of IDD over time and across sectors, and the inability to rely on etiologies of IDD as they are frequently unknown.Aims: To identify diagnoses related to IDD in an administrative database and create a cohort of persons with IDD.Methods: Open-text diagnostic entries related to IDD were identified in an Ontario home care database (2003-2015) and coded as being either acceptable (e.g. Down syndrome) or ambiguous (e.g. intellectually challenged). The cognitive and functional skills of the resulting groups were compared using logistic regressions and standardized differences, and their age distributions were compared to that of the general home care population.Results: Just under 1% of the home care population had a diagnostic entry related to IDD. Ambiguous terms were most commonly used (61%), and this group tended to be older and less impaired than the group with more acceptable terms used to describe their IDD.Conclusions: Open-text diagnostic variables in administrative health records can be used to identify and study individuals with IDD. Implications: Future work is needed to educate assessors on the importance of using standard, accepted terminology when recording diagnoses related to IDD.