Article
First results of the interim analysis of the randomized controlled SVASONA trial for idiopathic normal pressure hydrocephalus (ISRCTN51046698)
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Published: | September 16, 2010 |
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Objective: The idiopathic normal-pressure hydrocephalus (iNPH) is a neurodegenerative disease which may be responsible for up to 6% of all dementia cases. The surgical implantation of a ventriculoperitoneal shunt represents the current standard of care. The results of the prospective Dutch iNPH study in 1997 proved that low pressure valves (<80 mmH2O) lead to a significantly better outcome compared with medium pressure valves (80–120 mmH2O). But this advantage is dearly bought with a very high rate of overdrainage complications. New posture-dependent gravity units that counterbalance hydrostatic pressure changes in the upright position were developed to overcome this problem. The aim of our study was to investigate whether a gravity unit is capable to allow good outcomes with programmable valves adjusted to low opening pressures without overdrainage complications.
Methods: SVASONA is a pragmatic randomized controlled trial conducted at seven centers in Germany. Patients with iNPH were randomly assigned to receive 1) a programmable valve with a gravity unit (proGAV, Miethke, Germany) or 2) a conventional programmable valve (Medos-Codman, Johnson & Johnson, Germany). Both devices are FDA-cleared. The institutional review boards of all collaborating centers approved the protocol. Written informed consent was obtained from all patients. The primary hypothesis was that the experimental device reduces the rate of overdrainage from 25% to 10%. As secondary endpoints, iPNH-specific outcome, generic quality of life (Short Form 36), and complications and serious adverse events (SAE) were recorded. The planned interim analysis for safety and efficacy was performed halfway and lead to a stop of the study due to significant confirmation of the hypothesis.
Results: Between 01/2007 and 10/2009 152 patients were included until the criteria for the planned interim analysis were reached. Concordant with our primary hypothesis we found a significant reduction in the rate of overdrainage using the gravity valve. The outcome according to the iNPH specific scores and the generic quality of life was marginally better in the gravity valve group.
Conclusions: Our prospective randomized study showed that gravity valves compared with the standard therapy significantly avoid overdrainage complications. We demonstrated significant evidence for a raise of patients’ safety by gravity valves in the treatment of iNPH.