Study	Reason for exclusion
Blagovesh 1990	ALLOCATION: Not a random comparison of HBOT versus an alternative
Cuixia 2008	ALLOCATION: Non‐random controlled study
Dauman 1993	ALLOCATION: Randomised controlled trial PARTICIPANTS: Patients with sudden hearing loss INTERVENTIONS: Both groups received hyperbaric oxygen
Dundar 2007	ALLOCATION: No indication of randomisation and included post‐viral hearing loss
Joachims 1978	ALLOCATION: Case series only
Lamm 1995	ALLOCATION: Review only, no new data
Lamm 1998	ALLOCATION: Review only, no new data
Li 2010	ALLOCATION: Not a random comparison of HBOT versus an alternative
Lina 2010	ALLOCATION: Not a random comparison of HBOT versus an alternative
Sano 1988	ALLOCATION: Case series
Sparacia 2003	ALLOCATION: Randomised controlled trial PARTICIPANTS: Patients with sudden hearing loss INTERVENTIONS: All patients received hyperbaric oxygen
Tisch 2000	ALLOCATION: Review, no new data
Wang 2000	ALLOCATION: Not a randomised comparison
Xiao 1986	ALLOCATION: Randomised controlled trial PARTICIPANTS: Patients with sudden hearing loss INTERVENTION: All patients received hyperbaric oxygen

HBOT: hyperbaric oxygen therapy