| Methods |
Cluster RCT.
Power calculation: no.
Follow‐up period: 3 weeks after discharge. |
| Participants |
2953 patients undergoing elective clean surgery.
Exclusion: patients with a temperature of 37.5oC on the day of or day before surgery, infection remote from operation site, antibiotics given within 7 days prior to surgery for infection, incarcerated inguinal hernia, radical mastectomy.
Baseline comparability: age, sex, type of surgery, antibiotic prophylaxis, hair washed, hair removal method, wound drainage. |
| Interventions |
All patients had 2 showers;1 the day before surgery and 1 on the day of surgery.
Group 1: used 50 ml of chlorhexidine 4% for each shower;
Group 2: placebo.
Special application instructions were provided to all participants. |
| Outcomes |
Primary outcome:
Wound infection was defined in the report as "inflammation of the surgical wound with discharge of pus, spontaneous and/or after surgical intervention that occurs during hospitalisation or during routine follow‐up"
Group 1: 37/1413 (2.6%);
Group 2: 33/1400 (2.4%). |
| Notes |
|
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
Randomisation was carried out for each surgical unit by means of computer‐generated patient trial numbers. |
| Allocation concealment (selection bias) |
Low risk |
Bottles of solution were contained in boxes of 10, each holding 5 chlorhexidine and 5 placebo in random sequence. Unless the code was broken, it was impossible to know which preparation the patient had used. |
| Blinding (performance bias and detection bias)
Investigator and participant |
Low risk |
Neither patients nor investigators were aware of group allocation. |
| Blinding (performance bias and detection bias)
Outcome assessor |
Low risk |
Outcome assessment was by routine surveillance methods employed by individual hospitals (infection control nurse or surgeon). They were unaware of group allocation. |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
140 (4.7%) patients were withdrawn after randomisation either because the patient was not operated on (62 patients), had had 1 bath only (26), operation not stated 'clean' (14) or had a current infection (38). The withdrawals were evenly distributed between the chlorhexidine and placebo groups. |
| Selective reporting (reporting bias) |
Low risk |
All data reported. |
| Other bias |
Low risk |
ICI supplied the bathing materials. However, as results favoured the placebo group, this is unlikely to have affected results. |
