Zhao 2016

Methods	Design: RCT, factorial design
Participants	Baseline: 60 participants were divided into 6 groups. We reported the results of 9 participants in the 10‐second heparin injection group and 10 participants in the 30‐second heparin injection group ‐ 13 male and 6 female; mean age in the intervention group was 61.5 (SD 11.5) years and in the control group 61.6 (SD 6.5) years. Setting: patients who were hospitalised in the cardiology unit of a university hospital in China Country: China Injection site: about 5 cm up and down the navel Injection protocol: injection without drug aspiration Inclusion criteria: received SC injection of enoxaparin sodium 4100 IU; were conscious; platelet values were within the limits of 100,000 to 300,000/dL; activated partial thromboplastin time (APTT) in the reference range 25 to 37.5 seconds; no large abdominal skin bruising, induration, or skin disease; not taking antiplatelet drugs such as aspirin or clopidogrel before the start of the study Exclusion criteria: liver and kidney dysfunction, significant weight loss, body mass index less than 18.5 kg/m2, previously injected with LMWH
Interventions	Slow injection (30‐second injection) as intervention vs fast injection of heparin (10‐second injection) as control
Outcomes	Site pain intensity was assessed by VAS (0 to 100 mm) immediately after each injection. Extent of injection site bruising was evaluated at 48 hr after injection with ruler to measure the maximum diameter of bruise recorded as mm.
Notes	Funding sources: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random number table used
Allocation concealment (selection bias)	Unclear risk	Method not stated
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding of participants and personnel was impossible in this trial.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Researcher who evaluated outcomes was blinded to the group.
Incomplete outcome data (attrition bias) All outcomes	High risk	One participant in the control group (10%) was lost to follow‐up. Study did not report intention‐to‐treat analysis.
Selective reporting (reporting bias)	Low risk	All stated outcomes were reported.
Other bias	Unclear risk	Other aspects of heparin injection (e.g. heparin temperature, syringe size, needle gauge, injection volume, air bubble in the syringe) were not clearly described. This may have affected outcomes.

APTT: activated partial thromboplastin time. CIS: Cochrane Vascular Information Specialist. cm: centimetres. hr: hours. IU: international units. LMWH: low molecular weight heparin. mm: millimetres. RCT: randomised controlled trial. SC: subcutaneous. SD: standard deviation. VAS: visual analogue scale.