Every country in the world is experiencing growth in both the size and the proportion of older persons. As a result of the changes, the profile and needs of people with medical illnesses have evolved. How care is delivered to patients has to keep pace with these changes, or patients will experience poor care at high cost and not have their needs met. A new model of care has emerged to meet these challenges: Acute Medical Unit. Despite considerable investment and popularity of this model, questions remain:

1.  Who benefits most from this care model?
2. How may these models be most effectively implemented for the best results?
3. How effective are these models?

Singapore is well-placed to answer these questions with its national healthcare system and excellent research institutions. The investigators plan to study how effective the model is by comparing patients with similar profiles exposed to both these care models compared to how hospital care is usually provided, looking for four differences:

1. how long patients stay in hospital,
2. how often they use the emergency department
3. quality of health
4. cost

Additionally, the investigators seek to characterise patterns of health needs for this group of patients.