Disability severity transitions in the community-dwelling Swiss ageing population: secondary analysis of the Swiss version of the Survey of Health, Ageing and Retirement in Europe (SHARE) using multistate models.

Multimorbidity increases the risk of transitioning to higher disability severity states and death across most transitions.

• HRs between 0.90 and 2.34 for model A (multimorbidity operationalised as count) compared with not being multimorbid
• HRs between 0.95 and 1.46 for model B (multimorbidity operationalised as burden score) for a one-point increase in the disease burden score
• Findings were similar across both operationalisations of multimorbidity
• Analysis conducted using multistate Markov models with proportional hazards assumption

Higher age is associated with increased likelihood of transitioning to higher disability severity states and death.

• HRs between 1.00 and 1.14 for model A for a 1-year increase in age
• HRs between 1.00 and 1.15 for model B for a 1-year increase in age
• The association was consistent across both multimorbidity operationalisation models
• Study population was community-dwelling adults aged 50+ in Switzerland

Transitions to death are less likely for women compared with men.

• HRs between 0.34 and 0.88 for model A for women compared with men
• HRs between 0.38 and 0.71 for model B for women compared with men
• The sex effect was specific to transitions to death, not transitions between disability severity states
• This finding was consistent across both multimorbidity models

The study used an overall functioning score to define four disability severity states (no, mild, moderate, and severe) and death as a fifth state.

• Disability severity states were defined as no, mild, moderate, and severe disability, plus death
• The overall functioning score was previously developed prior to this study
• Death status was assessed using the SHARE end-of-life interview
• Multistate Markov models were used to conduct transition analysis between states

The study sample consisted of 3505 community-dwelling Swiss adults aged 50 or older with at least two interviews in SHARE.

• N=3505 participants included in the secondary analysis
• Data sourced from the Swiss version of the Survey of Health, Ageing and Retirement in Europe (SHARE)
• Inclusion criterion required participants to have at least two interviews
• Population was community-dwelling, not institutionalised

Two distinct operationalisations of multimorbidity — count-based and burden-based — produced similar findings when analysed in separate models.

• Model A used a count-based operationalisation of multimorbidity
• Model B used a disease burden score operationalisation of multimorbidity
• Both models yielded similar patterns of association with disability severity transitions and death
• The authors note this study contributes to discussion on how to operationalise multimorbidity in healthy ageing research