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. 2013 Oct 20;2013(10):CD006823. doi: 10.1002/14651858.CD006823.pub2

Somers 1992.

Study characteristics
Methods Single‐centre prospective randomised controlled trial on 227 participants undergoing breast‐conserving therapy with level I and level II axillary dissection
Participants n = 227. Drain 108, no drain 119. Age of participants, years: drain 60.1 ± 12.8, no drain 59.3 ± 13.8 (mean ± SD)
Interventions Drain versus no drain. Jackson‐Pratt closed suction
Outcomes Seroma, total volume of drainage, total number of aspirations, number of days from surgery to final aspiration, wound infection, lymphoedema, impaired shoulder movement, haematoma, wound dehiscence
Notes Setting: Albert Einstein Medical Centre, Philadelphia, Pennsyvania, USA
Funding source not stated
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) High risk Randomisation method based on the last digit of the participant's admission number—pseudorandomisation. Code could easily be broken by surgeon performing several operations
Allocation concealment (selection bias) High risk Method only pseudorandomisation, so easy to crack code
Blinding of participants and personnel (performance bias)
All outcomes Unclear risk Cannot blind surgeons or participants to presence/absence of drain. Unclear what effect, if any, this would have
Blinding of outcome assessment (detection bias)
All outcomes Low risk Seroma defined: "any palpable or ballottable fluid collection"
Aspiration defined: "all collections were aspirated...regardless of size or symptoms"
Wound infection defined: "erythema, warmth or purulent drainage at incision site"
Incomplete outcome data (attrition bias)
All outcomes Unclear risk Clearly state why four patients were excluded from drain group because drains were left in for > 1 day, in breach of study protocol. 4/109—affects 3% of study population, but unclear why they went > 1 day—all could have developed infection, lots of aspirations required
Selective reporting (reporting bias) Low risk No unreported outcomes
Other bias Low risk No other biases in study design. Good write‐up with lots of detail and good objective definitions of study outcomes