[Survival in amyotrophic lateral sclerosis].
BACKGROUND
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder. Median survival from symptom onset is about 3.5 years, but some patients live for longer than 5 years. Because of fatal termination of ALS, searching for the prognostic factors related to the length of illness is very important.


METHODS
The aim of this study was to determine the mean duration of the disease and statistical probability of survival in our ALS population. In a 7-year-survey period (1985-1991), 58 patients with ALS were discovered in the Belgrade district. The outcome in 54 cases was determined by directly contacting patients or their families. Four patients (2 men and 2 women) could not be reached for follow-up and dropped out of the study after diagnostic hospitalization. The differences between the two arithmetic means were tested by Student's t-test. The probability of survival was obtained bythe life table method]. Differences in survival between subpopulations were evaluated by long-rank test.


RESULTS
Over the period from 1985 to 1991, fifty-eight patients were diagnosed as new cases of ALS in Belgrade. Our series comprised 35 men and 23 women. The mean age at onset of symptoms was 56.2 +/- 9.8 (55.9 +/- 7.6 in male and 56.6 +/- 12.5 in female group). Although female patients were somewhat older than male subjects at onset of the disease, this difference was not statistically significant (t = 0.805; p > 0.05). The clinical manifestation at the onset of the disease was bulbar in nine (15.5%) and spinal in 49 (84.5%) patients. The mean age at onset was 56.0 +/- 9.5 in the group with spinal ALS. The patients with bulbar ALS were older at onset (57.3 +/- 9.8), but this difference was not statistically significant (t = 0.49; p > 0.05). In order to gain better insight into the natural course of ALS in our population, we focused special attention on 32 patients who died during the survey period. The mean duration of ALS in our population was 27.7 +/- 18.2 months (approximately 2 years and 4 months). The cumulative probabilities of survival of a two-, five- and seven-year period were 62%, 27% and 27%, respectively. These findings refer to the total population. We also analyzed survival in relation to sex, age and clinical form of ALS. There was a difference of survival according to sex. A five-year survival was 22% in males and 36% in females; the same was noted after a seven-year survey period. The long-rank test detected no statistically significant difference (chi2 = 2.65; p > 0.05). Survival was compared between subgroups of patients with different forms of the disease (spinal and bulbar ALS). At the end of a four-year period no patient with bulbar ALS was in live, while 38.4% patients with spinal ALS were still alive (Fig. 1). This difference was statistically highly significant (long-rank test; chi2 = 3.44; k = 1; p < 0.01). There was a significant difference in survival between patients under and over 49 years (Fig. 2). A two-year survival for patients under 49 years was 88% and 57% for those over 49 years old. At the end of a five-year period these figures were 53% and 23%, respectively. More than 50% of the patients under 49 and only 19% of those over 49 years were alive at the end of the survey period (chi2 = 21.87; k=1; p < 0.01).


CONCLUSIONS
Advanced age and bulbar signs at onset indicated poorer prognosis in our population. The patients under 49 years had significantly higher survival rates than the older patients. The more benign course of ALS in younger patients was also confirmed by the other authors. The bulbar form of ALS had a significantly lower survival rate in comparison to the spinal form. These findings are also consistent with findings in other populations. Some possible explanations for different survivals of ALS patients are also discussed, including the hypothesis that the apolipoprotein Eepsilon 4 allele may influence the pattern of motor neuron loss.
Alcaz
S
S
Jarebinski
M
M
Pekmezović
T
T
Marinković
Z
Z
Apostolski
S
S
D017668:Age of Onset; D000690:Amyotrophic Lateral Sclerosis / Q000401:mortality*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D015996:Survival Rate