Survival in the oldest old: death risk factors in old and very old subjects

Factors predicting death in the ninth decade of life may differ from predictors in younger age groups. A prospective study was carried out on 210 subjects entering a residential home at the age of 68 to 79 years and of 287 subjects aged greater than or equal to 80 years who included 91 survivors from the first group; all subjects were followed until 78% of them had died. A Cox analysis was carried out with death as end point and 13 potential risk factors as covariates. Mildly impaired mobility at entry, defined as the need for help to walk 300-400 yards for various reasons, smoking, bacteriuria, and presence of ECG abnormalities were significant death risk predictors before age 80. Beyond this age, only mildly impaired mobility and serum cholesterol levels less than or equal to 5.9 mmol/L, as compared with levels greater than or equal to 8.0 mmol/L, remained significant. Higher hematocrit levels were predictors of survival before and after age 80. Systolic blood pressure, age, sex, weight, and socioeconomic status had no effect in either group. The data show that survival after age 80 is related only to adequate physical mobility and high hematocrit and cholesterol levels, regardless of the levels of other common risk factors.