Age at time of surgery does not influence outcome in idiopathic normal pressure hydrocephalus – a national quality registry study of 3082 patients

Purpose This study aims to investigate the outcome of shunt surgery in patients with idiopathic normal pressure hydrocephalus (iNPH) in relation to age at surgery, using data from the Swedish Hydrocephalus Quality Registry (SHQR). The disease affects older patients, with a mean age at diagnosis of 74 years. Since shunt surgery, which introduces a risk of serious complications, is the only available treatment, appropriate selection of patients eligible for surgery is essential. It has been suggested that higher age negatively affects outcome after shunt surgery. Methods Patients operated upon during January 2004–February 2022 were included. The inclusion criteria were: age ≥ 60 years and data available from ≥ 3 domains by the iNPH scale. Clinical outcomes were assessed at 3 and 12 months using the modified version of the iNPH scale (miNPH), the Timed Up-and-Go (TUG) test and the modified Rankin scale (mRS). These were related to 5-year-interval age groups. Results Improvement was seen in all age groups, with no statistically significant differences in outcome between age groups in miNPH score, TUG or mRS. The oldest group (> 85 years) showed significant improvements, as illustrated by miNPH scale score changes at 3 and 12 months of 4.3 (–8.1 to 21.5) and 10.1 (–6.5 to 36.8), respectively. Conclusions This population-based study shows similarly favourable outcomes across ages, suggesting that there should be no upper age limit for shunt surgery in patients with iNPH.