Huang 2002.

Methods	Random allocation. Blinding not reported.
Participants	160 opioid dependent by ICD‐10; Group sizes (1) 78 (2) 82. Duration of drug abuse 15 months to 11 years. 79% using by inhalation. 91% male, mean age 30.
Interventions	Naloxone 0.03mg/kg iv followed by naltrexone 0.6mg/kg by nasogastric tube under anaesthesia with propofol, midazolam and (1) ketamine or (2) tramadol. Anaesthesia maintained for 3 hours, iv tranquillizers for 2 hours. Inpatient treatment, general hospital.
Outcomes	Heart rate and blood pressure before and after anaesthesia, after each dose of naloxone, and after naltrexone. Main withdrawal symptoms before and after treatment.
Notes	Ten signs and symptoms of withdrawal assessed; scoring method not reported. Country: China
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Quote: "...volunteers were divided at random into two groups". Method of sequence generation not reported.
Allocation concealment?	Unclear risk	Method not reported.
Blinding? Subjective outcomes ‐ intensity of withdrawal, adverse effects	High risk	No blinding reported.
Blinding? Objective outcomes ‐ duration of treatment, completion of treatment	Low risk	These outcomes not reported, and considered unlikely to be affected by lack of blinding.
Incomplete outcome data addressed? All outcomes	Low risk	No drop out reported.
Free of selective reporting?	Low risk	None apparent
Free of other bias?	Low risk	None apparent
Other bias: Selection of comparison cohort	Low risk	Experimental and comparison groups drawn from same population.
Other bias: Comparability of cohorts	Unclear risk	Comparability of group demographics not reported.
Other bias: Representativeness of exposed cohort	Unclear risk	Participants described as volunteers, but means of recruiting participant and source population not reported.
Other bias: Ascertainment of exposure	Low risk	Data collection established by study protocol.