- Design
- Systematic review and random-effects meta-analysis of randomised trials with trial sequential analysis
- Population
- 224 adults aged 60 or over with idiopathic normal pressure hydrocephalus in four trials
- Primary outcome
- Change in gait speed
- Effect
- SMD 0.73 (95% CI 0.45 to 1.01); functional independence OR 3.92; positional headache OR 5.62 (1.16 to 27.18)
This PRISMA-compliant meta-analysis pooled four randomised trials with 224 patients aged 60 or over with idiopathic normal pressure hydrocephalus. Trials compared immediate CSF shunting with placebo or no shunting. The primary outcome was change in gait speed.
Shunting improved gait velocity (standardised mean difference 0.73, 95% CI 0.45 to 1.01; P<0.0001). Functional independence also improved (OR 3.92), as did modified Rankin Scale scores (mean difference -0.73) and, more modestly, cognitive screening scores (SMD 0.37) and Symbol Digit Test performance (SMD 0.47). Trial sequential analysis found conclusive evidence for reduced functional disability.
Shunting increased positional headache (OR 5.62, 95% CI 1.16 to 27.18). Subdural haematoma was imprecisely estimated (OR 4.07, 0.62 to 26.94), and the authors stress that this does not mean the risk is absent; the largest included trial reported an excess of subdural bleeding. Effects on cognitive and urinary symptoms were more limited or uncertain.
With four small trials, the safety data are thin. The authors support shunting for carefully selected patients and call for larger trials with longer follow-up.
- Refer older patients with suspected iNPH for specialist assessment rather than watching and waiting.
- Counsel that gait and independence improved most, with more modest effects on cognition and urinary symptoms.
- Discuss the risk of positional headache and subdural bleeding; the bleeding estimate is imprecise.
- Select carefully; the authors emphasise patient selection and standardised outcome assessment.
Why it matters
Randomised evidence for shunting has historically been thin; this pooled analysis supports treating gait disturbance in iNPH as reversible.
Don't overread it
Four small trials leave major complications such as subdural haematoma too imprecise to rule in or out.
The statistics, in plain English
A standardised mean difference of 0.73 is a moderate-to-large effect on gait speed across trials that used different walking tests. With only 224 patients, wide intervals around rare harms such as subdural haematoma (0.62 to 26.94) cannot exclude a large increase.
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