Limits...
The quality of research synthesis in surgery: the case of laparoscopic surgery for colorectal cancer.

Martel G, Duhaime S, Barkun JS, Boushey RP, Ramsay CR, Fergusson DA - Syst Rev (2012)

Bottom Line: Reviews were synthesized, and outcomes were compared qualitatively.Overall survival was evaluated by ten reviews, none of which found a significant difference.Further systematic reviews or meta-analyses are unlikely to be justified without specifying a significantly different research objective.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Surgery, Department of Epidemiology & Community Medicine, and Ottawa Hospital Research Institute, The Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada. guillaume.martel@gmail.com

ABSTRACT

Background: Several systematic reviews and meta-analyses populate the literature on the effectiveness of laparoscopic surgery for colorectal cancer. The utility of this body of work is unclear. The objective of this study was to synthesize all such systematic reviews in terms of clinical effectiveness, to appraise their quality, and to determine whether areas of duplication exist across reviews.

Methods: Systematic reviews comparing laparoscopic and open surgery for colorectal cancer were identified using a comprehensive search protocol (1991 to 2008). The primary outcome was overall survival. The methodological quality of reviews was appraised using the Assessment of Multiple Systematic Reviews (AMSTAR) instrument. Abstraction and quality appraisal was carried out by two independent reviewers. Reviews were synthesized, and outcomes were compared qualitatively. A citation analysis was carried out using simple matrices to assess the comprehensiveness of each review.

Results: In total, 27 reviews were included; 13 reviews included only randomized controlled trials. Rectal cancer was addressed exclusively by four reviews. There was significant overlap between review purposes, populations and, outcomes. The mean AMSTAR score (out of 11) was 5.8 (95% CI: 4.6 to 7.0). Overall survival was evaluated by ten reviews, none of which found a significant difference. Three reviews provided a selective meta-analysis of time-to-event data. Previously published systematic reviews were poorly and highly selectively referenced (mean citation ratio 0.16, 95% CI: 0.093 to 0.22). Previously published trials were not comprehensively identified and cited (mean citation ratio 0.56, 95% CI: 0.46 to 0.65).

Conclusions: Numerous overlapping systematic reviews of laparoscopic and open surgery for colorectal cancer exist in the literature. Despite variable methods and quality, survival outcomes are congruent across reviews. A duplication of research efforts appears to exist in the literature. Further systematic reviews or meta-analyses are unlikely to be justified without specifying a significantly different research objective. This works lends support to the registration and updating of systematic reviews.

Show MeSH

Related in: MedlinePlus

Citation of previously published systematic reviews.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3351744&req=5

Figure 5: Citation of previously published systematic reviews.

Mentions: The pattern of citations of previously published systematic reviews is presented in Figure 5. In total, nine (33%) reviews did not cite any pre-existing work. The maximum number of cited existing systematic reviews was five, which was found in two reviews [29,40]. All other studies cited zero to four pre-existing systematic reviews. The mean number of cited existing reviews was 1.6 (95% CI: 1.0 to 2.2). The mean ratio of cited to total existing systematic reviews was 0.16 (95% CI: 0.093 to 0.22), ranging from 0 to 0.5. All three Cochrane Reviews (0, 0.048 to 0.091) and the more recent HTA report (0.18) had citation ratios that were less than 0.2. There was no correlation between the citation ratio and the AMSTAR score (r = 0.047) or the journal's 5-year impact factor (r = -0.099) for individual reviews. In total, 13/26 pre-existing reviews were cited at least once, with 5 of these accounting for 71% of all citations (29/41) [17-19,22,26]. Figure 5 shows that five reviews were cited disproportionately more frequently, and that all five reviews were published in the earlier portion of the literature review.


The quality of research synthesis in surgery: the case of laparoscopic surgery for colorectal cancer.

Martel G, Duhaime S, Barkun JS, Boushey RP, Ramsay CR, Fergusson DA - Syst Rev (2012)

Citation of previously published systematic reviews.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3351744&req=5

Figure 5: Citation of previously published systematic reviews.
Mentions: The pattern of citations of previously published systematic reviews is presented in Figure 5. In total, nine (33%) reviews did not cite any pre-existing work. The maximum number of cited existing systematic reviews was five, which was found in two reviews [29,40]. All other studies cited zero to four pre-existing systematic reviews. The mean number of cited existing reviews was 1.6 (95% CI: 1.0 to 2.2). The mean ratio of cited to total existing systematic reviews was 0.16 (95% CI: 0.093 to 0.22), ranging from 0 to 0.5. All three Cochrane Reviews (0, 0.048 to 0.091) and the more recent HTA report (0.18) had citation ratios that were less than 0.2. There was no correlation between the citation ratio and the AMSTAR score (r = 0.047) or the journal's 5-year impact factor (r = -0.099) for individual reviews. In total, 13/26 pre-existing reviews were cited at least once, with 5 of these accounting for 71% of all citations (29/41) [17-19,22,26]. Figure 5 shows that five reviews were cited disproportionately more frequently, and that all five reviews were published in the earlier portion of the literature review.

Bottom Line: Reviews were synthesized, and outcomes were compared qualitatively.Overall survival was evaluated by ten reviews, none of which found a significant difference.Further systematic reviews or meta-analyses are unlikely to be justified without specifying a significantly different research objective.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Surgery, Department of Epidemiology & Community Medicine, and Ottawa Hospital Research Institute, The Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada. guillaume.martel@gmail.com

ABSTRACT

Background: Several systematic reviews and meta-analyses populate the literature on the effectiveness of laparoscopic surgery for colorectal cancer. The utility of this body of work is unclear. The objective of this study was to synthesize all such systematic reviews in terms of clinical effectiveness, to appraise their quality, and to determine whether areas of duplication exist across reviews.

Methods: Systematic reviews comparing laparoscopic and open surgery for colorectal cancer were identified using a comprehensive search protocol (1991 to 2008). The primary outcome was overall survival. The methodological quality of reviews was appraised using the Assessment of Multiple Systematic Reviews (AMSTAR) instrument. Abstraction and quality appraisal was carried out by two independent reviewers. Reviews were synthesized, and outcomes were compared qualitatively. A citation analysis was carried out using simple matrices to assess the comprehensiveness of each review.

Results: In total, 27 reviews were included; 13 reviews included only randomized controlled trials. Rectal cancer was addressed exclusively by four reviews. There was significant overlap between review purposes, populations and, outcomes. The mean AMSTAR score (out of 11) was 5.8 (95% CI: 4.6 to 7.0). Overall survival was evaluated by ten reviews, none of which found a significant difference. Three reviews provided a selective meta-analysis of time-to-event data. Previously published systematic reviews were poorly and highly selectively referenced (mean citation ratio 0.16, 95% CI: 0.093 to 0.22). Previously published trials were not comprehensively identified and cited (mean citation ratio 0.56, 95% CI: 0.46 to 0.65).

Conclusions: Numerous overlapping systematic reviews of laparoscopic and open surgery for colorectal cancer exist in the literature. Despite variable methods and quality, survival outcomes are congruent across reviews. A duplication of research efforts appears to exist in the literature. Further systematic reviews or meta-analyses are unlikely to be justified without specifying a significantly different research objective. This works lends support to the registration and updating of systematic reviews.

Show MeSH
Related in: MedlinePlus