Factors affecting survival of patients with neurodegenerative disease

Survival varies widely among different neurodegenerative diseases. Data on the role of the Mini Mental State Examination (MMSE) and apolipoprotein E (APOE) in survival are sparse except for Alzheimer's disease (AD).

We studied mortality of 3,581 patients in an academic clinic from 1993 to 2004. Average follow-up was 4.1 years. We studied patients with amyotrophic lateral sclerosis (ALS) (n = 174), possible AD (n = 206), probable AD (n = 1,175), Parkinson's disease (PD) (n = 661), mild cognitive impairment (MCI) (n = 357), frontotemporal dementia (FTD) (n = 94), Lewy body disease (LBD) (n = 64), and controls (n = 850). We compared patients' mortality to the US population and to controls.

Mortality ranged from 7% for controls to 58% for ALS patients. The median survival times from initial visit for PD, FTD, probable AD, possible AD, LBD, and ALS were 8.9, 7.0, 5.9, 5.6, 5.3, and 2.7 years, respectively. Mortality rate ratios comparing each disease to controls were 39.43, 7.25, 3.70, 3.51, 2.47, 2.73, and 1.61 for ALS, FTD, LBD, PD, probable AD, possible AD, and MCI, respectively. A lower initial MMSE score was associated with higher mortality for probable AD, PD, and MCI, while APOE4 predicted mortality for PD and LBD. Non-whites had 20% lower mortality rates than whites for all dementias combined, adjusting for education.

All neurologic diseases, including MCI, had increased mortality versus controls. A lower MMSE score and APOE4 presence predicted higher mortality for some patient groups.