Epidemiology and practice variations of shunt surgery for hydrocephalus: a nationwide registry–based study

Abstract

OBJECTIVE Indications for surgical treatment of hydrocephalus (HC) can vary across centers. The authors sought to investigate the frequencies of surgically treated HC disorders and to study variations in the practice of shunt surgery in Norway, a country with universal and free healthcare. METHODS This is a nationwide registry–based study using data from the Norwegian Patient Registry. Four neurosurgical centers serve exclusively in 4 defined geographic regions. All patients who underwent shunt surgery in Norway between January 1, 2008, and December 31, 2021, were included and regional differences and time trends were explored. RESULTS The national annual rate of shunt surgery in the study period was 6.0 per 100,000. A total of 4139 individuals (49.5% male) underwent primary shunt surgeries, and a total of 9262 operations including revision surgeries were performed. There were statistically significant regional differences between the 4 treating centers in Norway in terms of patients’ age (median 61 years, range 53–65 years); mean annual rate of primary shunt surgery (5.1–7.6 per 100,000); annual rate of primary shunt surgery in patients of different age groups (0.9–1.2 in 0–17 years, 1.8–2.7 in 18–64 years, and 1.6–3.9 in ≥ 65 years); annual rate of revision surgeries (2.4–5.7 per 100,000); annual rate of primary surgery for communicating HC (0.7–2.0 per 100,000); annual rate of primary surgery for normal pressure HC (0.5–1.8 per 100,000); and annual rate of primary surgery for HC associated with cerebrovascular disease (0.5–2.0 per 100,000). There was significant variation in overall shunt surgeries during the study period (p = 0.026), and there was an overall decrease in revision surgeries over time (p < 0.001). There appears to be a homogenization of revision surgeries over time. CONCLUSIONS There are significant and large practice variations in the surgical management of HC in Norway. There are significant differences between regions, particularly in terms of rates of shunt surgery for some diagnoses (communicating HC, normal pressure HC, and HC associated with cerebrovascular disease) as well as revision rates.