Predictors of adverse outcomes and cost after surgical management for idiopathic normal pressure hydrocephalus: Analyses from a national database

•Drivers of adverse outcomes were investigated for surgical management of iNPH.•The median (IQR) LOS was 3 days (2–5), with 37.3 % rate of non-routine discharge.•Median (IQR) cost was $11,230 ($7,735–15,590).•Emergent admission was the most important predictor of adverse outcomes. We utilized a national administrative database to investigate drivers of immediate adverse economic and hospital outcomes, including non-routine discharge, prolonged length of stay (LOS), and admission costs among patients undergoing surgery for idiopathic normal pressure hydrocephalus (iNPH). The National Inpatient Sample (NIS) was queried from 2007 to 2017 for patients aged ≥60 with a diagnosis code for iNPH undergoing surgery. Multivariable logistic-regression models and Wald χ2 were used to identify drivers of non-routine discharge, prolonged length of stay (LOS) (>75th percentile) and higher admission costs (>90th percentile). A total of 13,363 patients with iNPH undergoing surgical management were identified. The most common comorbidity reported in the cohort was a cardiovascular pathology (56.9 %, n = 7,787), followed by urinary pathology (37.2 %, n = 5,084), osteoarthritis (7.8 %, n = 1,071), Alzheimer’s disease (4.6 %, n = 626) and cerebrovascular pathology (4.2 %, n = 569). The most frequently employed procedure was ventriculo-peritoneal (VP) shunt placement (65.6 %, n = 8,942) of which 89.8 % (n = 8,027) were performed open and 10.2 % (n = 915) laparoscopically. This was followed by lumbo-peritoneal (LP) shunting (15.5 %, n = 2,115), lumbar puncture alone (screened, serial CSF removal) (14.8 %, n = 2,013), endoscopic third ventriculostomy (ETV) (2%, n = 274), ventriculo-atrial (VA) shunt (0.95 %, n = 130) and ventriculo-pleural (Vpleural) shunt (0.46 %, n = 64). The median (IQR) LOS was 3 days (2–5), the rate of non-routine discharge was 37.3 % and median (IQR) cost was $11,230 ($7,735–15,590). On multivariable-analysis, emergent-admission (OR 2.91), older age (76–90: OR 1.55; 90+: OR 2.66), VP shunt (open: OR 3.09; laparoscopic: OR 2.32), ETV (OR 3.16), VA/VPleural shunt (OR 2.73) and hospital admission in Northeast-region compared to Midwest (OR 1.27) were found to be associated with increased risk of non-routine discharge. Some of the highly significant associated factors for prolonged LOS included emergent-admission (OR 11.34), ETV (OR 10.92), VA/VPleural shunt (OR 7.79) and open VP shunt (OR 8.24). For increased admission costs, some of the highly associated facto