Professor Jane Hutton

A major determinant of the economic cost of being disabled is the expected length of the disabled person’s life.
 
Health and social care providers, whether insurance companies or state authorities, need information on life expectancy in order to plan for the medical, educational and social needs of disabled people.
 
If medical liability is admitted, information on life expectancy is an essential component in deciding how much money is awarded. The UK Health services pay out millions of pounds to children with cerebral palsy—brain-damage which results in physical disability. Although medical doctors are often asked to give an opinion on a patient, they rarely have detailed follow-up of well-defined, large cohorts, or knowledge of methods for unbiased estimation of survival probabilities.
 
To provide a reliable estimate, good data and good statistical models are required. The most reliable source of information on survival is a precisely defined geographical cohort, with accurate records of the dates of onset and death and of factors which affect lifetime. The UK has excellent records of dates of death, but if many people in a cohort are still alive, methods which allow for unknown length of life are required. The relevant statistical approach is to use survival regression models. Choosing models which give consistent, accurate and robust estimates, even when some data are missing, is essential.