People with intellectual disability experience inadequate health care and have unmet health needs that can go unidentified or be poorly managed. Health assessments have been shown to significantly increase short-term clinical activity for people with intellectual disability. The aim of this study was to more accurately quantify the effect of health assessments for people with intellectual disability by comparing health actions recorded in health assessment booklets to actions recorded in general practitioners’ (GPs) records in the 12-month period following the health assessment. Participants were people with intellectual disability who had received a Comprehensive Health Assessment Program (CHAP), living in the community. The CHAP is a health assessment that is demonstrated to significantly increase health actions, compared with usual care, for people with intellectual disability. Data collected from three randomised controlled trials conducted in South-East Queensland, Australia, from 2000 to 2010 were pooled and analysed. The health assessment booklet contained significantly more information on health actions than GPs’ records. Notably, hearing tests (risk ratio (RR) = 5.9; 95% confidence interval (CI) = 4.7–7.4), breast checks (RR = 3.9; 95% CI = 2.7–5.7), and skin examinations (RR = 7.9; 95% CI = 5.9–10.7) were more likely to be recorded in the CHAP booklet. Health assessments increase health actions for people with intellectual disability to a significantly greater extent than previously demonstrated.