Obesity in women and underweight in both men and women was more common in adults with ID than in the general population after controlling for differences in the age distributions between the two populations. The associated factors suggest opportunities for targeting high-risk groups within the ID population for lifestyle and behaviour modification.

This study demonstrates that, compared to a matched sample, there is a greater prevalence of obesity amongst women with Down syndrome but not men. As the impact on the health of people with Down syndrome of being overweight or obese is uncertain, this is an area that requires further study.

The relatively high SMRs observed in young people and in women, particularly those living in inner city areas and with Down syndrome, deserve further investigation for possible explanations, including socio-economic factors.

Strategies to reduce inequalities in people with ID need to focus on decreasing mortality from potentially preventable causes, such as respiratory infections, circulatory system diseases and accidental deaths. The lack of mention of ID on death certificates highlights the importance of effective record linkage and ID reporting in health and social care settings to facilitate the government's confidential inquiry into causes of death in this population.

South Asian and white populations have similar prevalences of ID and related psychological morbidity. Culturally appropriate services for South Asian adults may need to focus on skill development and community care.