Disentangling the roles of disability and morbidity in survival to exceptional old age

Abstract

Background: Although it is commonly held that survival to age 100 years entails markedly delaying or escaping age-related morbidities, nearly one-third of centenarians have age-related morbidities for 15 or more years. Yet, we have previously observed that many centenarians compress disability toward the end of their lives. Therefore, we hypothesize that for some centenarians, compression of disability rather than morbidity is a key feature for survival to old age.

Methods: This cross-sectional, nationwide study included 523 women and 216 men 97 years or older. The participants were stratified by sex and age at onset (age <85 years [termed survivors] and age >or=85 years [termed delayers]) of chronic obstructive pulmonary disease, dementia, diabetes, heart disease, hypertension, osteoporosis, Parkinson disease, and stroke. Dependent variables were the Barthel Activities of Daily Living Index (Barthel Index) and the Information-Memory-Concentration test of the Blessed Dementia Scale.

Results: Thirty-two percent of the participants were survivors. For men with hypertension and/or heart disease for 15 or more years, the median Barthel Index score was 90 (independence range, 80-100). For female survivors with hypertension, heart disease, and/or osteoporosis, the median Barthel Index score was 65 (minimal assistance range, 60-79). Generally, men had better function than women: 60% of male survivors had Barthel Index scores of 90 or higher compared with 18% of female survivors (P < .001) and 50% of male delayers had Barthel Index scores of 90 or higher compared with 27% of females delayers (P < .001).

Conclusions: Whereas the compression of both morbidity and disability are essential features of survival to old age for some centenarians, for others, the compression of disability alone may be the key prerequisite. Though far fewer in number, male centenarians tend to have significantly better cognition and physical function than their female counterparts.

Figure 1

Level of cognitive impairment for male and female centenarians. Blessed Dementia Scale scores higher than 34 indicate normal cognition; 27 to 33, mild impairment; 21 to 26, moderate impairment; and lower than 21, severe impairment. The subjects who were not able to complete the Information-Memory-Concentration test because of dementia were included in the severe impairment category.

Figure 2

Distribution of Barthel Activities of Daily Living Index (Barthel Index) scores by sex and morbidity group. Frequency of Barthel Index scores for male and female centenarians by morbidity group: age at onset younger than 85 years (A, female; B, male) and age at onset 85 years or older (C, female; D, male).