Wang 1984.

Methods	Randomised, controlled Method of randomisation: a table of random numbers Type of shunt: ventriculoperitoneal shunts Location: Canada Follow‐up: "until the last patient contact" Duration: 20 months
Participants	Inclusion: all patients that underwent ventriculoperitoneal shunt surgery at their hospital Exclusion: VPS infection within the preceding month. Received antibiotics within the previous week or patients who were known to be allergic to the intervention drug Treatment: 55; control: 65
Interventions	5 mg/kg trimethoprim and 25 mg/kg sulphamethoxazole IV. The first dose 1 hour before surgery. The second and third dose were given 8 and 16 hours after surgery. Control: dextrose solution given at the same time slot
Outcomes	Proportion of participants who had shunt infection Mean days after surgery before onset of infection in the trimethoprim group was 24.5 days and 47 days in the sulphamethoxazole group
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"table of random numbers"
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"double blinded"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not described
Incomplete outcome data (attrition bias) All outcomes	Low risk	7 exclusions due to infection diagnosed perioperatively. Exclusions well defined
Selective reporting (reporting bias)	Low risk	Study protocol is not available but it is clear that the published report includes all expected outcomes
Other bias	Low risk	The study appears to be free of other sources of bias

IV = intravenous