Fig. 4

Percentage of exposed individuals by year of observation ^{a, b,c}. ^a Method 4 can contain more than one individual where first intellectual disability diagnosis date is greater than the date of entry (e.g. a person entering the cohort in 2000 but diagnosed first with intellectual disability in 2006 enters the cohort without intellectual disabilities in 2000 and enters again with intellectual disabilities in 2006). ^b Please note that, as a random sample of the general population without intellectual disabilities for the comparison (unexposed) group, this graph cannot be interpreted as representing prevalence of intellectual disability. ^c As Method 3 involved matching on cohort entry at a 1:10 ratio by design, approximately 10% of the sample had intellectual disabilities throughout the observation period