Authors' objectives

To assess the recurrence rates after inguinal hernia repair using the Shouldice technique, in a systematic review of controlled trials using a meta-analysis if possible .

Searching

MEDLINE was searched from 1966 to 1994, and EMBASE from 1974 to 1994, using the keywords 'inguinal hernia' and 'Shouldice'. Abstract books of international meetings and recent journals were handsearched. Studies identified included journal articles and abstracts.

Study selection

Assessment of study quality

The following criteria were used to assess the quality of the retrieved studies: patient characteristics, comparability of study groups, type of hernia, number of patients, method of randomisation, operative technique used, method of follow-up, and outcome measure. The trials were scored and listed in order of decreasing quality. A maximum score of 9 was possible when all the criteria were positive. Details of the scoring method used and of the scores of the individual trials are given. Three authors individually assessed the quality and scored the trials. Any differences in quality assessment were discussed and full agreement was reached.

Data extraction

Three authors individually collected the information. The authors of the primary studies were contacted where abstracts lacked the necessary information.

Methods of synthesis

Results of the review

There were 9 articles of prospective controlled trials included in the review (3,633 patients, 7 randomised trials and 2 non-randomised trials. Two of the articles examined 4 treatment arms and were considered as 4 individual studies in the analysis, giving a total of 11 studies.

Using all 11 studies, the recurrence rates were lower after Shouldice repair in 10 of the 11 studies. In 5 of the 11 studies this difference was significant.

Pooling of the 6 randomised trials scoring over 5 for quality, using the Mantel-Haenzel method, gave a RR ratio of 0.62 (95% CI: 0.44, 0.87) in favour of the Shouldice technique.

The sensitivity analysis produced ORs of 0.60 (95% CI: 0.43, 0.83) and 0.63 (95% CI: 0.44, 0.90) when using the fixed- and random-effects models, respectively. No statistical heterogeneity was demonstrated amongst the trials (P=0.28).

When the 2 lowest scoring randomised trials were included in the pooled results, the RR was 0.66 (95% CI: 0.49, 0.89) in favour of the Shouldice technique.

Authors' conclusions

The Shouldice technique is probably the best conventional method of hernia repair and results for laparoscopic repair and other methods should be measured against this standard.

CRD commentary

This is a well-written and clearly-presented review with an excellent discussion on the sources of potential bias. The quality of all the retrieved studies was assessed and scored by three individuals using unambiguous predefined criteria. Unpublished studies reporting negative results may, as discussed by the authors, have been omitted thus biasing the results in favour of the Shouldice technique. The limited follow-up period from 18 months to 5 years may have considerably underestimated the recurrence rate. The authors state that only 50% of the recurrences at 20 years are detectable within a 2 to 5 year period. It is not stated whether the proportion of eventual recurrences detectable at 5 years varies according to the technique of repair used or whether the results are applicable to the Shouldice technique. There are a number of sources of potential bias discussed comprehensively by the authors, including the level of surgical expertise of the surgeon, the experience the surgeon has of the Shouldice technique, the type of suture material used, methods of follow-up, and the outcome measures used. The authors state that the treatment groups were comparable with respect to patient demographics, but no mention is made of the comparability with respect to other variables such as the level of the surgeon, the surgeons experience with the Shouldice technique, or the suture material used. Information on some of the above may have been available from the original authors. It is not stated whether those assessing the outcome were blinded to the treatment group. Also, there appears to be a slight discrepancy between the results of the pooling presented in Table 4 and those reported in the text.

Implications of the review for practice and research

In view of the above potential sources of bias it is unclear whether the Shouldice technique is superior to other methods of herniorrhaphy in preventing recurrence.

Bibliographic details

Simons M P, Kleijnen J, van Geldere D, Hoitsma H F, Obertop H. Role of the Shouldice technique in inguinal hernia repair: a systematic review of controlled trials and a meta-analysis. British Journal of Surgery 1996; 83(6): 734-738. [PubMed: 8696728]

Other publications of related interest

DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials 1986;7:177-88.

Indexing Status

Subject indexing assigned by NLM

MeSH

Controlled Clinical Trials as Topic; Hernia, Inguinal /surgery; Humans; Randomized Controlled Trials as Topic; Surgical Procedures, Operative /methods; Suture Techniques

AccessionNumber

11996001005

Database entry date

31/01/1998

Record Status

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.