The authors concluded that there was no significant difference between Vypro II and polypropylene mesh in short-term effectiveness. Use of Vypro II mesh was associated with reduced feeling of a foreign body inside. The conclusions appear reliable. The small number of included studies for each pooled analysis should be borne in mind.

To compare the effectiveness of Vypro II mesh and polypropylene mesh after inguinal hernia repair.

PubMed, The Cochrane Library, EMBASE, Science Citation Index and Chinese Biomedical Literature Databases were searched (all from inception to May 2009). Search terms were reported. Reference lists of identified primary studies, abstract booklets and review articles were handsearched. No language restriction was applied. Only articles published in peer reviewed journals were considered.

Randomised controlled trials (RCTs) that compared Vypro II mesh with standard polypropylene mesh for inguinal hernia repair were eligible for inclusion. Outcomes assessed included recurrence, pain, urinary tract infection, seroma, feeling of a foreign body and testicular atrophy.

Most of the operations were Lichtenstein. Types of inguinal hernias in the included patients varied (unilateral primary or recurrent and bilateral primary or recurrent). Types of standard polypropylene mesh varied (premilene, prolene, Surgipro). Study follow-up periods varied and ranged from eight weeks to five years.

Two reviewers assessed studies for inclusion; disagreements were resolved by consensus.

Two reviewers independently assessed study quality using criteria outlined in Cochrane Handbook for Systematic Reviews of Interventions. Key criteria assessed were sequence generation, allocation concealment, blinding of participants, personnel and outcome assessors, intention-to-treat analysis, handling of incomplete outcome data, selective outcome reporting and other sources of bias.

Data on numbers of patients with outcomes were extracted to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Authors were contacted for additional outcome data where these were not reported.

The authors did not state how many reviewers performed data extraction.

Pooled odds ratios and 95% CIs were calculated using fixed-effects meta-analysis. Heterogeneity was assessed using X² and I². Sensitivity analysis was done based on study quality. Subgroup analyses explored potential clinical differences between trials that could modify magnitudes of treatment effects.

Ten RCTs (n=2,027 participants, range 108 to 591) were included. Three studies included the same patients with different follow-up durations. Seven studies reported adequate information on randomisation, allocation concealment and blinding.

No significant differences were found between Vypro II mesh and polypropylene mesh in one-year recurrence and total recurrence, postoperative pain within one year, urinary tract infection, seroma and testicularly atrophy. Vypro II mesh was associated with significantly lower feeling of a foreign body (OR 0.58, 95% CI 0.42 to 0.80, I²=37%; four RCTs, n=1,305).

No results were reported for sensitivity analysis.

There was no significant difference between Vypro II and polypropylene mesh in short-term effectiveness. Use of Vypro II mesh was associated with reduced feeling of a foreign body inside.

The review question was clearly stated. Relevant sources were searched. There were no language limitations, which minimised potential for language bias. Relevant papers may have been missed as only articles published in peer-reviewed journals were considered. Study selection and quality assessment were conducted in duplicate, which reduced potential reviewer error and bias; it was unclear whether similar steps were followed during data extraction. Study quality assessment was reported and used appropriate criteria; it was unclear whether the findings were used to inform the synthesis. The decision to combine results using meta-analysis was appropriate given the absence of significant heterogeneity.

The authors' conclusions are based on the presented evidence and appear reliable; the small number of included studies for each pooled analysis should be borne in mind.

Practice: The authors did not state any implications for practice.

Research: The authors stated that further high-quality RCTs with long follow-up periods were needed.

None stated.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.