Survival times in people with dementia: analysis from population based cohort study with 14 year follow-up
BMJ 2008; 336 doi: https://doi.org/10.1136/bmj.39433.616678.25 (Published 31 January 2008) Cite this as: BMJ 2008;336:258
- Jing Xie, research associate1,
- Carol Brayne, professor1,
- Fiona E Matthews, senior research scientist2
- and the Medical Research Council Cognitive Function and Ageing Study collaborators
- 1Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Cambridge CB2 0SR
- 2MRC Biostatistics Unit, Institute of Public Health, Cambridge
- Correspondence to: C Brayne carol.brayne{at}medschl.cam.ac.uk
- Accepted 11 November 2007
Abstract
Objectives To provide estimates of survival after onset of dementia by age, sex, self reported health, disability, and severity of cognitive impairment.
Design Analysis of participants from prospective population based cohort study in 1991-2003, with follow-up of dementia status in all individuals after two and six years (in one centre) and 10 years and in subsamples additionally at six and eight years and mortality until 2005.
Setting Multicentre population based study in England and Wales: two rural and three urban centres.
Participants 438 participants who developed dementia from a population based study of 13 004 individuals aged 65 years and over drawn from primary care population registers.
Main outcome measures Sociodemographic factors, cognitive function, specific health conditions, and self reported health collected at each interview. Cox’s proportional hazards regression models were used to identify predictors of mortality from the selected variables in people who received diagnosis of dementia according the study’s criteria.
Results By December 2005, 356 of the 438 (81%) participants who developed dementia during the study had died. Estimated median survival time from onset of dementia to death was 4.1 years (interquartile range 2.5-7.6) for men and 4.6 years (2.9-7.0) for women. There was a difference of nearly seven years in survival between the younger old and the oldest people with dementia: 10.7 (25th centile 5.6) for ages 65-69; 5.4 (interquartile range 3.4-8.3) for ages 70-79; 4.3 (2.8-7.0) for ages 80-89, and 3.8 (2.3-5.2) years for ages ≥90. Significant factors that predicted mortality in the presence of dementia during the follow-up included sex, age of onset, and disability.
Conclusion These analyses give a population based estimated median survival for incident dementia of 4.5 years. Such estimates can be used for prognosis and planning for patients, carers, service providers, and policy makers.
Footnotes
We thank colleagues in the cognitive function and ageing study group for their cooperation in data collection and management. We are also grateful to all the respondents, their families, and their primary care teams from across the country for their continued participation in the study.
Contributors: All authors contributed to writing the paper. CB initiated the study. JX undertook the analysis and prepared the manuscript. CB and FEM supervised the work and edited the paper. JX is guarantor of the data analysis. CB is overall guarantor for the whole study.
Funding: Medical Research Council and Department of Health (grant No: G9952).
Competing interests: None declared.
Ethical approval: Multi-centre research ethics committee approval and ethical approval from the relevant local research ethics committees.
Provenance and peer review: Not commissioned; externally peer reviewed.
- Accepted 11 November 2007