Obesity, Underweight and Risk of Death Among People with and without Disabilities

Background

Obesity and underweight are both strongly associated with mortality risk, but their impact may differ across population groups. People with disabilities represent a vulnerable population with distinct health profiles, yet evidence on BMI-related mortality in this group remains limited. This study aimed to examine the association between BMI and risk of death among people with and without disabilities over a follow-up period of up to 17 years.

Methods

This study used the National Health Insurance health check-up database. A total of 16,463,178 adults aged ≥20 years who underwent health check-ups between 2006 and 2008 were included after excluding those with extreme BMI values (<15 or > 50 kg/m²) or those who died within two years. Participants were classified into six BMI groups, ranging from underweight (<18.5 kg/m²) to severe obesity (≥40.0 kg/m²). Multivariable Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

The risk of death by BMI showed an inverted J-shaped pattern, with the highest risk observed among underweight people with disabilities compared with normal-weight people without disabilities (HR: 6.81, 95% CI: 6.67–6.95). After adjustment, the association followed a U-shaped pattern, with the highest risk among underweight people with severe disabilities (aHR: 2.48, 95% CI: 2.39–2.56). The risk of death was also particularly high among underweight people with internal organ disabilities (aHR: 4.63, 95% CI: 4.29–4.99) and severely obese people with developmental and mental disabilities (aHR: 4.91, 95% CI: 3.39–7.11).

Conclusions

Underweight posed the greatest risk, especially among those with severe and internal organ disabilities, while severe obesity was associated with increased risk among people with developmental and mental disabilities. These findings highlight the need for tailored strategies addressing both undernutrition and obesity in people with disabilities.

Key messages

• Underweight was associated with the highest risk of death among people with disabilities, particularly those with severe and internal organ disabilities.

• Risk of death across BMI categories differed by disability status and type, highlighting the need for tailored strategies to address both underweight and severe obesity.