Systematic review and meta-analysis in anatomic pathology

Underutilization of Meta-analysis in Diagnostic Pathology

CONTEXT

Underutilization of Meta-analysis No studies to our knowledge have investigated citations and utilization of meta-analysis in diagnostic pathology (DP).

OBJECTIVE

To characterize meta-analyses in DP compared with meta-analyses in medicine.

DESIGN

We searched PubMed for meta-analyses in 12 major DP journals without specifying years and in 4 major medicine journals in both 2006 and 2011. We compared articles' adjusted citation ratios (ACRs), defined as an article's citation count divided by the mean citations for the meta-analysis, review, and original research articles published in the same journal in the same year.

RESULTS

Forty-one of 76 DP articles, 74 of 125 medicine articles in 2011, and 52 of 83 medicine articles in 2006 were qualified meta-analyses as identified by PubMed. The ACRs of DP meta-analysis articles were higher than those of original research articles (2.62 ± 2.31 versus 0.92 ± 0.84, P < .001) and similar to those of review articles in 2006 (2.62 ± 2.31 versus 1.95 ± 1.59, P = .50), but they were similar to both in 2011 (1.85 ± 1.39 versus 0.99 ± 1.43, P = .11; 1.85 ± 1.39 versus 1.12 ± 1.43, P = .21, respectively). Diagnostic pathology and medicine meta-analyses had similar ACRs (1.85 ± 1.39 versus 1.57 ± 1.35 in 2011, P = .60; and 2.62 ± 2.31 versus 1.85 ± 1.90 in 2006, P = .50, respectively). However, although DP journals published fewer meta-analyses (0.97% versus 6.66% in 2011 and 0.67% versus 4.40% in 2006, P < .001 for both), they published more meta-analyses using both original and published data than medicine (21.95% versus 1.59%, P < .001). They also published more meta-analyses per year in 2011-2014 than in 2000-2010 (6.4 ± 1.29 versus 1.36 ± 1.03 articles per year, P < .001).

CONCLUSIONS

We found underutilization of meta-analyses in DP, despite their high ACRs and recently increased utilization. More DP meta-analyses are needed.

Underutilization of Meta-analysis in Diagnostic Pathology

Context

No studies to our knowledge have investigated citations and utilization of meta-analysis in diagnostic pathology (DP).

Objective

To characterize meta-analyses in DP compared with meta-analyses in medicine.

Design

We searched PubMed for meta-analyses in 12 major DP journals without specifying years and in 4 major medicine journals in both 2006 and 2011. We compared articles' adjusted citation ratios (ACRs), defined as an article's citation count divided by the mean citations for the meta-analysis, review, and original research articles published in the same journal in the same year.

Results

Forty-one of 76 DP articles, 74 of 125 medicine articles in 2011, and 52 of 83 medicine articles in 2006 were qualified meta-analyses as identified by PubMed. The ACRs of DP meta-analysis articles were higher than those of original research articles (2.62 ± 2.31 versus 0.92 ± 0.84, P &lt; .001) and similar to those of review articles in 2006 (2.62 ± 2.31 versus 1.95 ± 1.59, P = .50), but they were similar to both in 2011 (1.85 ± 1.39 versus 0.99 ± 1.43, P = .11; 1.85 ± 1.39 versus 1.12 ± 1.43, P = .21, respectively). Diagnostic pathology and medicine meta-analyses had similar ACRs (1.85 ± 1.39 versus 1.57 ± 1.35 in 2011, P = .60; and 2.62 ± 2.31 versus 1.85 ± 1.90 in 2006, P = .50, respectively). However, although DP journals published fewer meta-analyses (0.97% versus 6.66% in 2011 and 0.67% versus 4.40% in 2006, P &lt; .001 for both), they published more meta-analyses using both original and published data than medicine (21.95% versus 1.59%, P &lt; .001). They also published more meta-analyses per year in 2011–2014 than in 2000–2010 (6.4 ± 1.29 versus 1.36 ± 1.03 articles per year, P &lt; .001).

Conclusions

We found underutilization of meta-analyses in DP, despite their high ACRs and recently increased utilization. More DP meta-analyses are needed.

Frequency of K-ras mutations in pancreatic intraductal neoplasias associated with pancreatic ductal adenocarcinoma and chronic pancreatitis: a meta-analysis

Molecular analyses have demonstrated mutations in the K-ras gene at codon 12 in the majority of pancreatic ductal adenocarcinomas (PDACs). In order to determine whether the K-ras mutation rate increases parallel to the grade of dysplasia in duct lesions, we performed a meta-analysis of the studies published between 1988 and 2003 that provide information on K-ras mutations in hyperplastic and dysplastic duct lesions in the pancreas. The described duct lesions were reclassified according to the nomenclature for pancreatic intraepithelial neoplasia (PanIN), and the molecular methods for detecting K-ras were reviewed. In PanIN lesions from pancreata of patients with PDAC, there was a stepwise increase in K-ras mutations that correlated with the grade of dysplasia of the PanIN lesion. K-ras mutations were found in 36%, 44%, and 87% of PanIN-1a, 1b, and 2-3 lesions, respectively (trend statistic P <.001). Mutation-enriched polymerase chain reaction (PCR) resulted in higher rates of K-ras mutations in PanIN than plain PCR did. The incidence of K-ras mutations in PanIN lesions associated with chronic pancreatitis (CP) or normal pancreas was low (around 10%). In CP, K-ras mutations were only found after a disease duration of 3 years. The correlation of the incidence of K-ras mutations with the grade of dysplasia in PanIN and the occurrence of these mutations in CP with a duration of more than 3 years underlines the importance of this genetic change for the development of PDAC.

The application of special technologies in diagnostic anatomic pathology: is it consistent with the principles of evidence-based medicine?

Proponents of evidence-based medicine (EBM) have emphasized the need to consider the quality of different sources of medical information and have proposed various methods to integrate available "best evidence" into rules, guidelines and other diagnostic, therapeutic and prognostic models. The various factors that can affect the internal validity of studies in anatomic pathology, such as interobserver variability, use of retrospective rather than prospective data and others, are reviewed. The need for testing for the external validity of the results of anatomic pathology studies is introduced, using "test sets" of cases that have not been used to generate the classification or prognostic models. This methodology has been seldom used in anatomic pathology to validate the generalizability of various "entities," usefulness of diagnostic tests under different conditions and other information. Basic concepts of meta-analysis for research synthesis are introduced; these methods have been seldom used in anatomic pathology to integrate information from different studies using quantitative techniques rather than summary tables that merely list the results of various publications. The potential use of decision analysis and value of information analysis for the adoption of new tests is briefly discussed.