Arambasik 2013.

Methods	Allocation: randomized Controlled: placebo and active comparator Blinding: double‐blind Arm: 2‐arm, parallel treatment group, pilot study Centre: single centre Study dates and duration: 16‐month period trial (June 2011 to October 2012)
Participants	Inclusion criteria: not reported Exclusion criteria: not reported Baseline characteristics N: 37 participants; 37 VOC episodes Age (mean): 29.9 years Gender: F 13, M 24 Number randomized: 17 intervention, 20 control Number completed: number of participants at each follow‐up time not explicitly stated Setting of recruitment and treatment: not reported Country and sites: Akron General Medical Centre, Akron, OH, USA
Interventions	Duration of treatment: individual time to resolution of crisis Follow‐up period: not reported Treatment group (17 participants; 17 VOC episodes): IV hydromorphone 2 mg 15 minutes later: IV hydromorphone 2 mg + IV ketamine 6.2 mg/kg Control group (20 participants; 20 VOC episodes): IV hydromorphone 2 mg 15 minutes later: IV hydromorphone 2 mg + IV saline placebo 6.2 mg/kg Cointerventions/additional analgesia: not reported
Outcomes	Primary outcomes Pain score (VAS 0–10) Secondary outcomes Not reported
Notes	Abstract only, sufficient data on pain scores Sources of funding: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "this pilot study was randomised, prospective, double‐blinded trial." Comment: unclear details of randomization.
Allocation concealment (selection bias)	Unclear risk	Quote: "this pilot study was randomised, prospective, double‐blinded trial." Comment: unclear details of concealment.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "this pilot study was... double‐blind..." Comment: insufficient information, unclear method of blinding.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: insufficient information from abstract.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: insufficient information from abstract.
Selective reporting (reporting bias)	Unclear risk	Comment: primary outcome was reported in methods and results. However, unclear what other outcomes were from this abstract alone.
Size	High risk	Comment: total 37 participants, fewer than 50 participants per treatment arm.
Other bias	Unclear risk	Comment: unclear due to only abstract available.