6-minute walk test and the 3-metre backward walk test are sensitive to postoperative gait improvement in idiopathic normal pressure hydrocephalus.

Background: Gait impairment is a core symptom in idiopathic normal pressure hydrocephalus (iNPH), but commonly used tests like the 10-metre walk test (10MWT) may underestimate postoperative improvements. We evaluated the 6-minute walk test (6MWT) and 3-metre backward walk test (3MBWT) as outcome measures compared with 10MWT and Timed Up and Go (TUG) and explored sex-related and age-related differences in shunt-operated patients with iNPH. Methods: A retrospective study of 291 shunted patients with iNPH (62.5% male; mean age 73.3±6.2 years) was conducted. Gait function was assessed preoperatively and at a median of 5.4 months postoperatively. Outcomes were analysed using linear regression, with age and sex as covariates; improvement was described as per cent change from baseline. Correlations between tests were assessed with Spearman coefficients. Results: Postoperative changes were observed for all gait measures: 3MBWT time (40% reduction (95% CI 36% to 44%)), 6MWT distance (32% increase (95% CI 23% to 43%)), TUG time (28% reduction (95% CI 24% to 32%)) and 10MWT time (19-23% reduction (95% CI 16% to 25%)) at maximal speed and self-selected speed. Women performed worse than men both before and after shunt insertion, but improvement did not differ by sex when adjusting for baseline performance. Each 5-year increase in age reduced gait improvement by 3-8% (p<0.05). Preoperatively, 6MWT correlated strongly with 10MWT (ρ=-0.81) and 3MBWT with TUG (ρ=0.75), while the correlation between 6MWT and 3MBWT was moderate (ρ=-0.58) (all p<0.001). Conclusions: The 3MBWT and 6MWT capture postoperative gait changes and may provide complementary information to conventional gait assessments in iNPH.