Poulson 1983.

Methods	RCT Setting: hospital, Denmark
Participants	n = 21 started the trial; 18 completed the trial (A) 7 (B) 11 5 men/13 women Age: 26 to 86 years Patients with infected laparotomy wounds, a minimum of 7 cm, requiring opening and drainage Inclusion criteria: wound infection following laparotomy surgery; operations included: appendicectomy, bowel surgery, cholecystectomy, hysterectomy, repair of ventral hernia, wound infection which necessitated opening and drainage of the wound Minimum length of wound 7 cm Maximum depth of wound 7 cm Exclusion criteria: patients with burst abdomen, stoma or fistula in the vicinity of the wounds, because this increased the risk of continuous wound contamination
Interventions	A and B: initial drainage and removal of necrotic tissue method of removal not stated All wounds dressed with saline dressings to secure haemostasis (A) Twice‐daily dressings, necrotic tissue removed; dressing soaked in 20 ml solution (streptokinase/streptodornase) applied; solution provided by hospital pharmacy (B) Twice‐daily dressings, necrotic tissue removed; dressing soaked in 20 ml solution applied; solution provided by hospital pharmacy (saline)
Outcomes	Primary outcome: mean time to clean wound bed and closure by secondary suture: (A) 5.00 days (SD = 2.16) (B) 13.45 days (SD = 6.77) Statistically significant (P < 0.05, both Student's t‐test and Mann‐Whitney U‐test) Secondary outcomes: (1) Patient satisfaction: neither group of patients complained of significant wound discomfort; no data or statistics presented (2) Rate of infection: not reported (3) Quality of life: not reported (4) Length of hospital stay (median): (A) 2.2 days less than group B (B) Not reported (5) Cost‐effectiveness: not reported (6) Adverse events: 3 patients were excluded from the evaluation for non completion of the treatment; in group A 1 patient died of a pulmonary embolism and the other required further surgery for intra‐abdominal sepsis; 1 patient in group B was withdrawn as a result of abdominal dehiscence
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Pharmacy undertook the randomization" (p245), however no details are given regarding how this randomisation was done
Allocation concealment (selection bias)	Low risk	Pharmacy prepared the solutions (20 ml Varidase or 20 ml saline)
Blinding (performance bias and detection bias) Participants and personnel	Unclear risk	Not explicitly stated and therefore judged as unclear. However, it would be highly unlikely that participants and personnel would have been able to tell which solution was being applied as both ampoules contained 20 ml of clear solution, so unlikely to influence results. On p246 the authors state "only when the code was broken 11 patients were found to have saline and 7 had Varidase".
Blinding (performance bias and detection bias) Outcome assessors	Unclear risk	Not explicitly stated and therefore judged as unclear. However, it would be highly unlikely that outcome assessors would have been able to tell which solution was being applied as both ampoules contained 20 ml of clear solution, so unlikely to influence results. On p246 the authors state "only when the code was broken 11 patients were found to have saline and 7 had Varidase".
Incomplete outcome data (attrition bias) All outcomes	High risk	From the 21 originally recruited, 3 were withdrawn: 2 from the placebo group and one from the Varidase group. These 3 were excluded from the results presented and therefore no ITT analysis was undertaken. Rationales were given for the withdrawal.
Selective reporting (reporting bias)	Unclear risk	No study protocol available The stated aim of the trial was "to show, by means of a prospective clinical trial with randomised double blind procedure if Varidase is superior to conventional management of infected laparotomy wounds" (p245). However, they do not state what constitutes 'superior' and how this would be measured. The study reports number of days required for wound dressing and number of days in hospital (within discussion section). Size of wound and type of bacterial growth recorded at the start of the trial; this is not reported on again within the results.