Comorbid chronic diseases, discordant impact on mortality in older people: a 14-year longitudinal population study.
OBJECTIVE
To determine the impact of comorbid chronic diseases on mortality in older people.


METHODS
Prospective cohort study (1992-2006). Associations between numbers of chronic diseases or mutually exclusive comorbid chronic diseases on mortality over 14 years, by Cox proportional hazards model adjusting for sociodemographic variables or Kaplan-Meier analyses, respectively.


METHODS
Population based, Australia.


METHODS
2087 randomly selected participants aged ≥65 years old, living in the community or institutions.


RESULTS
Participants with 3-4 or ≥5 diseases had a 25% (95% CI 1.05 to 1.5, p=0.01) and 80% (95% CI 1.5 to 2.2, p<0.0001) increased risk of mortality, respectively, by comparison with no chronic disease, after adjusting for age, sex and residential status. When cardiovascular disease (CVD), mental health problem or diabetes were comorbid with arthritis, there was a trend towards increased survival (range 8.2-9.5 years) by comparison with CVD, mental health problem or diabetes alone (survival 5.8-6.9 years). This increase in survival with arthritis as a comorbidity was negated when CVD and mental health problems or CVD and diabetes were present in disease combinations together.


CONCLUSIONS
Older people with ≥3 chronic diseases have increased risk of mortality, but discordant effects on survival depend on specific disease combinations. These results raise the hypothesis that patients who have an increased likelihood of opportunity for care from their physician are more likely to have comorbid diseases detected and managed.
Quality Use of Medicines and Pharmacy Research Centre, Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, GPO Box 2471, Adelaide 5001, Australia. gillian.caughey@unisa.edu.au
G E
GE
Caughey
E N
EN
Ramsay
A I
AI
Vitry
A L
AL
Gilbert
M A
MA
Luszcz
P
P
Ryan
E E
EE
Roughead
D000203:Activities of Daily Living / Q000523:psychology*; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002908:Chronic Disease / Q000401:mortality*; D015897:Comorbidity; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007407:Interviews as Topic; D008137:Longitudinal Studies; D008297:Male; D009026:Mortality / Q000639:trends; D012111:Residence Characteristics / Q000706:statistics & numerical data; D012647:Self-Assessment; D012959:Socioeconomic Factors; D013021:South Australia / Q000453:epidemiology