Locating and Selecting Appraisal Studies for Reviews

Understanding and Appraising Systematic Reviews and Meta-Analysis

Systematic reviews and meta-analysis seek to answer a pre-framed research question to lead to a valid answer through a systematic, explicit and reproducible method of locating; identifying, including and appraising appropriate trials. The results are synthesized considering the methodological rigor of included trials. While the meta-analysis quantitatively pools the results from individual included studies, the systematic review summarizes the findings as qualitative conclusions. These reviews are crux of evidence based dentistry for various stake-holders, i.e., clinicians, researchers and policy-makers. Although the meticulous methodology of systematic review and meta-analysis minimizes the elements of bias, yet the validity and reliability of their findings should be explored prior to translating their conclusions to practice. The goal of this paper is to familiarize readers with rationale, conduct and appraisal of systematic review and meta-analysis. Further, guidance is provided on tracing potential elements of bias in the review to enable readers to judge the quality of evidence generated from the review.

Increasing number of databases searched in systematic reviews and meta-analyses between 1994 and 2014

OBJECTIVES

The purpose of this study was to determine whether the number of bibliographic databases used to search the health sciences literature in individual systematic reviews (SRs) and meta-analyses (MAs) changed over a twenty-year period related to the official 1995 launch of the Cochrane Database of Systematic Reviews (CDSR).

METHODS

Ovid MEDLINE was searched using a modified version of a strategy developed by the Scottish Intercollegiate Guidelines Network to identify SRs and MAs. Records from 3 milestone years were searched: the year immediately preceding (1994) and 1 (2004) and 2 (2014) decades following the CDSR launch. Records were sorted with randomization software. Abstracts or full texts of the records were examined to identify database usage until 100 relevant records were identified from each of the 3 years.

RESULTS

The mean and median number of bibliographic databases searched in 1994, 2004, and 2014 were 1.62 and 1, 3.34 and 3, and 3.73 and 4, respectively. Studies that searched only 1 database decreased over the 3 milestone years (60% in 1994, 28% in 2004, and 10% in 2014).

CONCLUSIONS

The number of bibliographic databases searched in individual SRs and MAs increased from 1994 to 2014.

There is No Evidence on the Effect of the Attachment System on Implant Survival Rate, Overdenture Maintenance, or Patient Satisfaction

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Attachment systems for mandibular implant overdentures: a systematic review. Kim HY, Lee JY, Shin SW, Bryant SR.J Advanced Prosthodont 2012;4(4):197-203.

REVIEWER

Ahmed Yaseen Alqutaibi, BDS, MDSc, PhD(c)

PURPOSE/QUESTION

To address treatment outcomes depending on attachment systems for two-implant mandibular-supported overdentures in terms of (1) implant survival rate, (2) prosthetic maintenance and complications, and (3) patient satisfaction.

TYPE OF STUDY/DESIGN

Systematic review

LEVEL OF EVIDENCE

Level 2: Limited-quality, patient-oriented evidence

STRENGTH OF RECOMMENDATION GRADE

Grade B: Inconsistent, limited-quality patient-oriented evidence.

Searching one or two databases was insufficient for meta-analysis of observational studies

OBJECTIVE

To address methodologic issues in searching for observational studies by presenting database search methods and results.

STUDY DESIGN AND SETTING

Results of two literature searches for publications reporting on observational studies of alcohol consumption and the risk of breast cancer and large bowel cancer were compared, to evaluate the sensitivity of various bibliographic databases and search strategies, including hand-searching reviews and meta-analyses.

RESULTS

The target sensitivity of 90% of publications in the breast cancer search was achieved by starting with Medline, then adding Biosis, Embase, and SCI EXPANDED-SSCI, which provided a total of 72 (91%) of the 79 relevant publications. To reach a similar 89% sensitivity for large bowel cancer, at least Biosis, Dissertation Abstracts Online, Embase, ETOH, and Medline had to be searched, with the addition of hand search of reviews and meta-analyses.

CONCLUSION

Limiting a search to one or two databases when conducting meta-analyses of observational studies will not provide a thorough summary of the existing literature. The findings support recommendations to implement a comprehensive search of electronic databases and the reference lists of recent review articles and meta-analyses.