anticholinesterase_a..

ANTICHOLINESTERASES ET ALZHEIMER
QUESTION : Les anticholinestérases sont-ils utiles pour le traitement de la
maladie d’Alzheimer?
AUTEUR : Marie-Hélène Desrosiers (FÉVRIER 2008)
P
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patients avec démence
anticholinestérases
pas de traitement
amélioration des symptômes
CONTEXTE : Mon patron me montre un article qui explique que le bénéfice d’un
anticholinestérase n’est peut-être pas si intéressant Les anticholinestérases
dans le traitement de l’Alzheimer sont très populaires mais sont-ils vraiment
efficaces?
RECHERCHE
Cochrane : 2 revues systématiques
Article de controverse (voir contexte)
RESULTATS :
1) COCHRANE : Birks J. Cholinesterase inhibitors for Alzheimer's disease.
Cochrane Database of Systematic Reviews 2006, Issue 1.
The results of 10 randomized, double blind, placebo controlled trials demonstrate
that treatment for 6 months, with donepezil, galantamine or rivastigmine at the
recommended dose for people with mild, moderate or severe dementia due to
Alzheimer's disease produced improvements in cognitive function, on average 2.7 points (95%CI -3.0 to -2.3, p<0.00001), in the midrange of the 70 point
ADAS-Cog Scale. Study clinicians rated global clinical state more positively in
treated patients. Benefits of treatment were also seen on measures of activities
of daily living and behaviour. None of these treatment effects are large.
The effects are similar for patients with severe dementia, although there is very
little evidence, from only two trials.
More patients leave ChEI treatment groups (29%), on account of adverse events
than leave the placebo groups (18%).
2) COCHRANE : Birks J, Harvey RJ. Donepezil for dementia due to
Alzheimer's disease. Cochrane Database of Systematic Reviews 2006, Issue 1.
24 trials are included, involving 5796 participants, of which 15 reported results in
sufficient detail for the meta-analyses. Most trials were of 6 months or less
duration in selected patients. Patients in 20 trials had mild to moderate disease,
in two trials moderate to severe, and in two severe disease. Available outcome
data cover domains including cognitive function, activities of daily living,
behaviour, global clinical state, adverse events and health care resource costs.
For cognition there is a statistically significant improvement for both 5 and 10
mg/day of donepezil at 24 weeks compared with placebo on the ADAS-Cog scale
(-2.01 points MD, 95%CI -2.69 to -1.34, P < 0.00001); -2.80 points, MD 95% CI 3.74 to -2.10, P < 0.00001) and for 10 mg/day donepezil compared with placebo
at 24 weeks (5.55 SIB points, 95% CI 3.60 to 7.49, p<0.00001) and 52 weeks
(1.84 MMSE points, 95% CI, 0.53 to 3.15, P =0.006).
The results show some improvement in global clinical state (assessed by a
clinician) in people treated with 5 and 10 mg/day of donepezil compared with
placebo at 24 weeks for the number of patients showing improvement (OR 2.38,
95% CI 1.78 to 3.19, P = < 0.00001, OR 1.82, 95% CI 1.42 to 2.35, P < 0.00001).
Benefits of treatment were also seen on measures of activities of daily living and
behaviour, but not on the quality of life score. There were significantly more
withdrawals before the end of treatment from the 10 mg/day (289/1125 24% 10
mg/day vs 219/1079 20% placebo, OR 1.35, 95% CI 1.11 to 1.65, P = 0.003) but
not the 5 mg/day, (100/561 18% 5 mg/day vs 109/568 19% placebo, OR 0.91,
95% CI 0.68 to 1.24, P = 0.56) donepezil group compared with placebo which
may have resulted in some overestimation of beneficial changes at 10 mg/day.
Benefits on the 10 mg/day dose were marginally larger than on the 5 mg/day
dose. The results were similar for all severities of disease.
Two studies presented results for health resource use, and the associated costs.
There were no significant differences between treatment and placebo for any
item, the cost of any item, and for the total costs, and total costs including the
informal carer costs.
3) S Baillargeon,Lucie. Maladie d’Alzheimer, les inhibiteurs de la
cholinestérase sont-ils vraiment efficaces?. L’actualité médicale, 15 mars
2006, p. 52
Section Importance des résultats
"Bien que 19 des 22 études aient montré des résultats significatifs en faveur de
l'inhibiteur de la cholinestérase, les bénéfices sont tout au plus modérés. Que
signifie exactement un gain de 1.5 à 3.9 points sur l'échelle ADAS-cog? L'état
des patients s'est-il cliniquement amélioré? Non d'après des experts de la FDA
américaine qui estiment qu'une différence d'au moins 4 points est le minimum
suggérant un bénéfice clinique. Les résultats fondés sur l'impression de
changement rapportés par les aidants naturels sont également modestes."
CONCLUSION :
Selon la revue Cochrane, il semble y avoir un bénéfice démontrable, bien que
léger.
Par contre, l’article de l’Actualité médicale suscite la controverse. La suggestion
qu’une différence de 4 points sur 70 dans l’échelle d’évaluation utilisée est
nécessaire pour être cliniquement significative est intéressante, puisque ce n’est
pas le cas dans les études.
Il est donc probable que les anticholinestérases sont un traitement à offrir mais
on ne doit pas se sentir mal si il n’est pas possible de le donner pour diverses
raisons, par exemple à cause d’effets secondaires.