Clinical research study
Prediction of Mortality Risk in the Elderly

https://doi.org/10.1016/j.amjmed.2005.10.062Get rights and content

Abstract

Purpose

Ways to predict the risk of cardiovascular (CV) events or all-cause mortality have largely been derived from populations in which old and very old subjects were underrepresented. We set out to estimate the incremental prognostic utility of inflammation and atherosclerosis markers in the prediction of all-cause and CV mortality in elderly men.

Methods

In a prospective population-based cohort study, conventional CV risk factors were documented in 403 independently living elderly men. C-reactive protein (CRP) and interleukin (IL)-6 levels were measured. Carotid plaques were assessed by ultrasound. Analyses were performed with proportional hazards analyses, and bootstrapping was used for internal validation. Main outcome was CV and all-cause mortality occurring during 4 years of follow-up.

Results

Increasing tertiles of CRP, IL-6, and number of plaques were independently associated with all-cause and CV mortality. With information on age, carotid plaques, IL-6, and CRP yielded good discriminatory power for all-cause and CV mortality: area under the receiver operating characteristic curve (95% confidence interval), 0.76 (0.70-0.82) and 0.74 (0.68-0.80), respectively. Combined use of only IL-6 and plaque burden allowed identification of subjects with low and high mortality risk. The Framingham PROCAM and a Dutch Risk Function poorly predicted mortality risk, similar or worse than a model using age alone.

Conclusion

In the old and very old, IL-6 and number of carotid plaques are powerful predictors of mortality risk in the years to come. Conventional risk scores seem to perform unsatisfactorily.

Section snippets

Study Population and Outcome Ascertainment

The design of this single-center community-based prospective cohort study has been reported in detail.33 Briefly, 1567 men living independently in Zoetermeer, a medium-sized town in The Netherlands, were invited to join the study. Inclusion criteria were age more than 70 years and sufficient mobility to attend the baseline visit. A total of 403 men responded and gave written informed consent. The study was approved by the Medical Ethics Committee of the Erasmus University Hospital Rotterdam.

Results

During a follow-up period of 48 months (for survivors), 75 (19%) men died; the cause of death was CV disease in 31 of the men (8%). The mean time of death was 30 months since the study start (range, 3-47 months). The mean age of the cohort at study start was 78 years (range, 73-94 years), and their baseline characteristics are shown in Table 1.

The three different modalities of the Framingham Score and the PROCAM risk function did not discriminate all-cause or CV mortality (areas under the ROC

Discussion

The principal finding of the present study is that in the old and very old, CRP, IL-6, and the presence of carotid plaques seem to be particularly associated with a graded risk of all-cause and CV mortality. These markers of inflammation and atherosclerotic burden offer incremental prognostic value and allow good mortality risk prediction. Our findings expand the results of previous studies of the associations between inflammatory markers and morbidity/mortality in the elderly by demonstrating

Conclusion

In old and very old men, the risk of dying in the years to come is more adequately predicted by elevated levels of IL-6 and the presence of carotid plaques, whereas low IL-6 levels and fewer plaques predict survival. Conventional risk scores seem to perform unsatisfactorily in this age group.

Acknowledgments

The authors thank Hanneke van Meurs for performing the ultrasound measurements and gratefully appreciate the contribution of Dicky Mooiweer-Bogaerdt and Inge Haumersen to data collection. Andro Medical Research, Rotterdam, facilitated the investigation by offering assistance and its study center in the city of Zoetermeer. Finally, the cooperation of the city board and the general practitioners of the city of Zoetermeer is acknowledged.

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