Normal pressure hydrocephalus (NPH) is characterized by a triad of gait disturbance, cognitive impairment, and urinary incontinence (UI) (1). The latter affects approximately 48.1% of patients and contributes to caregiver burden (2). Shunt surgery (SS) has demonstrated benefits in alleviating UI, but its impact on caregiver burden remains insufficiently understood (3). This study aimed to evaluate how UI influences caregiver burden in NPH patients after SS.

This is a secondary analysis of a prospective observational cohort from our institution’s NPH Clinical Care Center (2016–2024). We included patients with confirmed NPH diagnosis who underwent SS following multidisciplinary board evaluation. UI severity was measured using the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-UI-SF), and caregiver burden using the Zarit Burden Interview (ZBI). UI was used to classify patients as slight (1–5), moderate (6–12), severe (13–18), and very severe (19–21). For ZBI scores, the following were considered: no burden (≤46), mild birden (47-55) and intense burden (≥56). Assessments were conducted at baseline and at 3, 6, and 12 months postoperatively. Primary outcomes were changes in UI severity and caregiver burden during follow-up in function to IU baseline severity. 

A descriptive analysis was conducted based on the nature of each variable. Group differences were evaluated using Kruskal-Wallis test for continuous variables and Fisher’s exact test for categorical variables. A repeated measures ANOVA (RM-ANOVA) was conducted to evaluate longitudinal changes in ICIQ-UI-SF and ZBI scores. Greenhouse-Geisser correction was applied when sphericity was violated. Factors included time (within-subject), baseline UI severity (between-subject), and time × severity interaction. Statistical significance was set at p < 0.05. Analyses were performed in Jamovi 2.3.21.

A total of 102 patients were analyzed. Baseline ICIQ-UI-SF scores differed across severity groups with a statistically significant difference for mild vs very severe (median 10 in mild vs. 16.5 in very severe; p = 0.050). ZBI scores were similar at baseline (p = 0.398). All groups showed a reduction in ICIQ-UI-SF scores, although those with very severe UI improved less (median 12 [IQR 3.75] at 12 months). 
RM-ANOVA revealed a significant time effect for ICIQ-UI-SF (F(3.37, 127.93) = 6.50, p < .001), indicating a global improvement in UI after surgery. No significant interaction was observed between time and baseline UI severity (F(10.10, 127.93) = 0.77, p = .661). For ZBI scores, no significant time effect was found (F(2.70, 48.64) = 2.30, p = .095), and no interaction with baseline UI severity was detected.

SS led to progressive UI improvement across all severity groups. Patients with mild UI showed the lowest ICIQ-UI-SF scores and early, sustained improvement, though the magnitude was limited by a floor effect. Those with severe and very severe UI showed a notable initial reduction, but continued to have the highest scores throughout follow-up, indicating partial improvement. The lack of a time × baseline severity interaction indicates that, although UI improved significantly over time, the degree of improvement was not influenced by baseline UI severity. Despite a trend toward reduced caregiver burden, there was no significant evidence of progressive reduction after SS. ZBI score changes were independent of UI severity, indicating a similar burden trajectory across groups.

While SS significantly improves UI, these changes do not correlate with a reduction in caregiver burden over the longitudinal measures. This may reflect the greater influence of cognitive decline on caregiver stress. Notably, patients with severe baseline UI may experience less complete resolution. Study limitations include lack of additional clinical variables and potential selection bias due to follow-up loss. Future research should integrate gait and cognitive outcomes and explore broader caregiver-related factors.

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