Defining different recovery trajectories following acute infections as a measure of frailty

Date of Approval
Application Number
Technical Summary

This proposal will reframe the concept of frailty by assessing the different patient recovery trajectories following a urine or respiratory community acquired infection 2005-2015. This will develop a framework for future frailty research that has true construct validity. Open population based cohorts will be used within routine healthcare data to map the different recovery trajectories across different dimensions. These will include consultation rates, prescription rates, diagnosis rates, specific diagnostic codes, sequences of codes, location of health care interactions (inpatient, community, care home), and mortality. Changes in each dimension from baseline will be assessed over time using within patient case series analysis. To efficiently and systematically identify the most common ordered sequences of events from many potential combinations sequential pattern mining will be used. These different recovery trajectories will then be stratified by pre-existing co-morbidity and frailty measures, and the characteristics of patients in each trajectory will be described. A Cox proportional hazards model will be used to adjust for the competing risks between the multiple different trajectories using cumulative incidence functions. This model will then be used to calculate the association of pre-existing the co-morbidity and frailty measures with each recovery trajectory.

Health Outcomes to be Measured

Admission and length of hospital stay
- Clinical consultation rates
- All cause mortality
- Prescription rates
- Discharge or admission to care home
- Increased mobility needs


Colin Crooks - Chief Investigator - University of Nottingham
Colin Crooks - Corresponding Applicant - University of Nottingham
John Gladman - Collaborator - Nottingham University Hospitals
Trevor Hill - Collaborator - University of Nottingham


HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation