Hoffmann 1995b.

Methods	Randomised controlled trial
Participants	20 participants with ISSHL, with or without tinnitus. All participants had no improvement after 14 days of pharmacological treatment with hydroxyethyl starch, pentoxifylline and cortisone.
Interventions	Control (10): no treatment HBOT (10): 100% oxygen at 1.5 ATA for 45 minutes daily, 5 days each week for 2 to 4 weeks (10 to 20 sessions)
Outcomes	Audiometry at 3 months, subjective tinnitus scale
Notes	Rank 6 for sample size: power to detect mean hearing improvement of 20 dB more in active group than control < 80%
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No clear statement of sequence generation "20 patients were randomised "
Allocation concealment (selection bias)	Unclear risk	No mention of concealment
Blinding (performance bias and detection bias) All outcomes	High risk	No blinding for any party "...an untreated control group..."
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No apparent losses to follow‐up, numbers not clearly reported
Selective reporting (reporting bias)	Low risk	No indication of missing outcomes
Other bias	Low risk	No obvious other sources of bias