Kochhar 2014.

Study characteristics
Methods	Double‐blind RCT Enrolment period: August 2007 to December 2012 Country: India Single centre
Participants	N: 217 participants Age (years; mean ± SD): PG: 37.42 ± 9.9; CG: 37.42 ± 11.5 % Men: 95.7% (overall study population) Inclusion criteria: unilateral or bilateral inguinal hernia, age 15 to 70 years Exclusion criteria: Patients allergic to the given antibiotic, recurrent hernia, strangulated hernia, pregnancy or lactation, an immune compromised state, antibiotic treatment within last 5 days, existing indication for antibiotic prophylaxis (i.e. valvular heart disease) BMI: not reported Skin antiseptic: not reported Operative time: not reported Method of repair: Lichtenstein technique with monofilament polypropylene mesh (hernioplasty) Drain use: not reported ASA class: not reported Anaesthesia method: not reported Hospitalisation method: inpatient Length of hospital stay: 1 day Surgeon: not reported
Interventions	Prophylactic group (PG): N: 109 antibiotic: amoxicillin clavulanic acid dose: 1.2 g number of doses: 1 route of administration: intravenous timing of administration: just before operation Control group (CG): N = 108 substance: equal volume of sterile saline
Outcomes	Wound infection definition: ASEPSIS criteria purulent discharge, erythema, wound breakdown) Follow‐up: 1 and 4 weeks SSSI N infected/N patients (%): PG: 4/106 (3.8%); CG: 5/106 (4.7%) DSSI: not reported (reported: "not necessary to remove any mesh") Adverse effects: not reported
Notes	Participants < 18 years old were included in this study Staphylococcus aureus, E. coli, Klepsiella pneumoniae bacteria were isolated from the wound infections Funding: nil.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “All patients were randomized to either intravenous placebo (control group) or antibiotic prophylaxis (study group) by block randomization”. No information on how randomisation was accomplished. However, the block randomisation method indicates that the randomisation methodology has been performed carefully to minimise bias.
Allocation concealment (selection bias)	Unclear risk	No information available
Blinding of participants and personnel (performance bias) All outcomes	Low risk	No information available, but performance bias is unlikely in this setting
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: “Surgeon who was not involved in surgery followed the case after 1 and 4 weeks post‐operatively”
Incomplete outcome data (attrition bias) All outcomes	Low risk	Missing outcome data balanced in numbers across intervention groups, with similar reason for missing data. The proportion of missing outcomes was considered not enough to have had a clinically relevant impact on the intervention effect estimate. Quote: “Out of the total study population 3 patients from the study and 2 patients from the control group were excluded postoperatively for development of URI and thus requirement of antibiotics.” Available‐case analysis was performed.
Selective reporting (reporting bias)	Low risk	The study protocol was not available but report includes all expected outcomes, including specification of SSSI
Other bias	Low risk	The study appears to be free of other sources of bias