Study	Reason for exclusion
Agarwal 2018	Retrospective study that reviewed medical records
ASERNIP‐S 2014	Health technology assessment of Miethke proSA® adjustable gravitational shunt
Baird 2014	Systematic review
Beez 2014	Retrospective study that reviewed medical records
Czosnyka 1990	Physiological study on valve mechanics
Czosnyka 2000	Letter
Czosnyka 2002	Physiological study on valve mechanics
Decq 1995	Retrospective study that reviewed medical records
Del Bigio 1998	Systematic review of in vitro studies
Drake 1996	Duplicate
Drake 1998a	Narrative review
Drake 2000	Duplicate
Eymann 2007	Prospective study with no control group
Felix 1983	Prospective study with no control group
Gruber 1984	Prospective study with no control group
Haberl 2009	Prospective study with no control group
Higashi 1994	Case series comparing different valves
Hoshide 2017	Editorial
Ito 2012	Systematic review
Jain 2005	Case series
Kiefer 2000	Case series comparing different valves
Legat 1996	Non‐randomised comparative study
Li 2017	Systematic review
Lund‐Johansen 1994	Case series comparing different valves
Mbabazi‐Kabachelor 2019	Randomised study that assessed the effects of antibiotic‐impregnated shunts
Meling 2005	Prospective study with no control group
Portnoy 1976	In vitro study
Rasul 2012	Systematic review
Sainte‐Rose 1993	Case series
Schatlo 2013	Retrospective study
Sinha 2012	Randomised trial of a shunt at different pressures
Smely 1997	Case series
Sotelo 2005	Wrong intervention (shunt of continuous flow did not include a valve device). Study population included normotensive hydrocephalus.
Symss 2015	Retrospective study
Villeda 1997	Case series
Wong 2012	Systematic review
Xenos 2003	Observational study
Xu 2013	Systematic review
Xu 2013a	Systematic review