The investigators will create a frailty index using health administrative data available for older people having surgery. The index will be based on the Canadian Study of Health and Aging Frailty Index and standard recommendations for creation of frailty indices.~Once derived the index will be tested to measure its association with outcomes, as well as its discrimination. Various representations of the frailty index will be tested (primary-as a continuous measure; secondary as a binary, categorical and fractional polynomial variable). Performance in subgroups will also be evaluated,
The investigators will create a frailty index using health administrative data available for older people having surgery. The index will be based on the Canadian Study of Health and Aging Frailty Index and standard recommendations for creation of frailty indices.