Neurodevelopmental Diagnoses Before, During, and After the COVID-19 Pandemic.

Importance: The COVID-19 pandemic and associated lockdowns resulted in changes to the way children learned, developed, and accessed health care. Objective: To evaluate changes in rates and rate trends of new neurodevelopmental diagnoses for children in Ontario, Canada, before, during, and after the COVID-19 pandemic. Design, Setting, and Participants: This population-based retrospective cohort study used administrative data from ICES to assess new neurodevelopmental diagnoses from March 14, 2015, to December 31, 2024, among 291 896 children aged 6 years or younger in Ontario. Exposures: The COVID-19 pandemic period, defined as March 14, 2020, to November 30, 2022, and the postpandemic period, defined as December 1, 2022, to December 31, 2024. Main Outcomes and Measures: Monthly rate of new neurodevelopmental diagnoses per 1000 child-months, defined as the total number of children with a neurodevelopmental diagnosis divided by the total number of child-months. Interrupted time series analysis using data before, during, and after the pandemic was performed to evaluate changes in rate levels or slopes between study periods. Results: A total of 291 896 children received a neurodevelopmental diagnosis during the study period. Of 1 481 844 children at risk, 130 418 received a diagnosis in the prepandemic period (mean [SD] age, 2.5 [1.6] years; 79 573 boys [61.0%]); of 1 115 791 children at risk, 86 383 received a diagnosis during the pandemic period (mean [SD] age, 2.4 [1.6] years; 52 943 boys [61.3%]); and of 1 014 792 children at risk, 75 095 received a diagnosis in the postpandemic period (mean [SD] age, 2.7 [1.6] years; 45 030 boys [60.0%]). In the prepandemic period, rates of neurodevelopmental diagnoses increased monthly (slope = 0.04; 95% CI, 0.03-0.05; P < .001). In the first month of the pandemic, rates of neurodevelopmental diagnoses decreased by 0.91 per 1000 child-months (95% CI, -1.56 to -0.25 per 1000 child-months; P = .01) compared with the expected rate in the absence of the pandemic. Rates recovered and remained stable, with no statistically significant differences in slopes between the prepandemic period and either during or after the pandemic. Conclusions and Relevance: This population-based cohort study showed no significant differences in rates of new neurodevelopmental diagnoses among children aged 6 years or younger from prepandemic rates in the pandemic and postpandemic periods. The rapid deployment of virtual care may have helped maintain health care access, facilitating diagnoses during the pandemic and postpandemic periods.