[Long-term survival related to cognitive performance in older adults treated at a tertiary hospital level]

To determine the association between cognitive performance and long-term survival in an elderly Mexican population sample.

In this retrospective, retrolective and observational study elderly subjects were assessed in the Geriatrics Clinic of the Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán" between January 1994 and August 1999 using a comprehensive geriatric assessment. All 2544 subjects for whom vitality status was known up to September 2002 were included in the analysis. Socio-demographic and health-related information was gathered during the clinical interview, and their emotional and functional status was determined using the Katz, Lawton and GDS scales. Cognition was measured using the Mini-Mental State Examination (MMSE), grouping the subjects according to their performance into four groups: normal-high performance, normal-low performance, mild-to-moderate impairment and moderate-to-severe impairment. Vitality status was determined by searching the hospital's clinical records or by telephonic contact with the patient or primary caregiver when needed.

Long-term mortality rates increased in a linear fashion as MMSE scores decreased (p < 0.001), even for MMSE scores over 24. This association persisted even after adjustment for comorbidity, depression, functional status and socio-demographic factors.

Patients showed a progressive decline in long-term survival according to their cognitive performances. MMSE scores between 24 and 27 were also associated with an increased mortality and should not be considered as normal, even if they are not sensitive enough to detect impairment.