Factors in Survival

by ALSN Staff on Fri, 2009-05-01 15:43

Factors in Survival:

Age at diagnosis, diagnostic delay, fronto-temporal dementia, gender, genetic factors and modifiers, type of onset and rate of progression all play a role in length of survival.

Factor Good or Bad? Notes
Age at Diagnosis

Generally, the younger the age of the individual at time of diagnosis, the longer the duration of the disease.

Survival time is longer for those who receive a diagnosis under age 45; diagnosis at old age (more than 65 years) is consistent with shorter survival time.

Age is likely a better predictor of prognosis than any other “unalterable” factor.

Evidence from a number of studies shows a strong correlation between age at diagnosis and length of survival.

Diagnostic Delay Typically, the longer it takes to receive a definitive diagnosis from time of onset, the better the odds for longer survival; a short interval from onset to diagnosis is associated with shorter survival. This may reflect the fact that more aggressive cases of ALS are more easily diagnosed; also, those who experience a slower course of disease may put off visiting a clinic.
Fronto-Temporal Dementia (Ftd) Studies have shown shorter survival time in patients with ALS-FTD than in those who have only ALS. FTD involves cognitive decline, including personality changes and language-related deficits. May be attributable to the tendency of those with ALS-FTD to refuse or ignore treatment recommendations, such as assisted ventilation and feeding tubes.
Gender Female gender is often associated with shorter length of survival; males, longer. Evidence for this is inconsistent and may be attributable to a greater incidence in women of bulbar-onset ALS, as well as more advanced age at onset of symptoms.
Genetic Factors Some familial forms of ALS have proven more aggressive than others. Disease duration may be longer or shorter depending on the gene involved and the exact mutation, and may differ even among family members.
Genetic/Epigenetic Modifiers It’s suspected that factors that cause genes to behave differently without actually changing the DNA may positively or negatively affect length of survival. These factors may apply in both familial and sporadic cases of ALS.
Rate of Progression

A slow rate of decline after disease onset tends to correlate with longer survival; the opposite is true for cases in which progression is rapid.

More severe symptoms at the time of diagnosis generally predict shorter survival time.

Studies show strong evidence to support a relationship between rate of progression and survival length.
Type Onset

Limb-onset (symptoms starting in an arm or leg) is consistent with an overall better prognosis.

Bulbar-onset (symptoms starting in the speaking, swallowing or facial muscles), typically more aggressive, is associated with shorter survival time.

Rates of progression in primary lateral sclerosis (PLS) and progressive muscular atrophy (PMA) are significantly slower.

Evidence for these associations varies with different studies, possibly as a result of differing use of terminology among physicians.
ALSN Staff
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