Quality of follow-up: a systematic review of the bariatric surgery research

Noah J Switzer, BSc, MD, Shaheed Merani, Daniel Skubleny, Xinzhe Shi, Jean-Sebastien Pelletier, Richdeep Gill, Daniel Birch, Christopher de Gara, Arya Sharma, Shahzeer Karmali. University of Alberta

Introduction. Follow-up is a major concern for interpreting results, especially in light of evolving surgical techniques. McMaster Evidence-Based Criteria for High Quality Studies states that follow-up for clinical studies of prevention or treatment should have follow-up of at least 80%. Bariatric surgery is a fast growing surgical field of great interest in the academic world, however the quality of follow up in a general sense remains unknown. This study, to our knowledge, is the first in the literature to systematically review the bariatric surgery literature with regards to adequacy of patient follow up.

Methods. A complete search of PubMed using the search terms gastric bypass, (obesity AND surgery) OR bariatric surgery, weight loss OR weight OR BMI OR body mass index. Due to the large amount of gastric bypass studies, the publication time was restricted to a range of five years (2007 – 2012), the language was limited to English, and only one major database, PubMed, was explored. Inclusion criteria included all English speaking RCTs, Cohort, Case-control, and case series studies with adult patients undergoing gastric bypass procedure between the years 2007-2012.

The primary outcome was loss to follow up (LTF) at 12 months and at the endpoint of the study. Secondary outcomes included length of follow up at analysis, number of patients enrolled in RYGB arm and total study, country of study origin, number of centers involved in the study, impact factor of publishing journal. McMaster Evidence-Based Criteria for High Quality Studies was used to assess the follow-up data and a Meta-regression was performed to identify indicators of high quality studies.

Results.103 papers were included in the review. The average follow up time for all studies was 29.5 months (range 4-120) For 12 month follow-up, only 41/103 (40%) of papers had adequate patient follow-up, 22/103 (21%) failed to meet the McMaster criteria and 40/103 (39%) failed to report any follow-up results. For follow-up at study end, only 40/103 (39%) of papers had adequate patient follow-up, 42/103 (41%) failed to meet the McMaster criteria and 21/103 (20%) failed to report any follow-up results. On average, 15% of patients were lost to follow-up at 12 months and 29% were lost to follow-up at the study’s end.

The meta-analysis separated the patients into two groups: all patients enrolled in the study and patients only enrolled in the gastric bypass portion of the study (when applicable). Only study duration (p=0.004) and if the study was performed in the United States of America (p=0.007) were predictive factors of meeting the McMaster criteria for high quality follow-up. The impact factor of the publishing journal (p=0.49), number of centres involved (p=0.255) and study type (p=0.722) were not predictive.

Conclusion. Follow up after bariatric surgery is underwhelming with only approximately 40% of studies meeting criteria for adequate follow-up. On average, nearly 30% of patients are lost to follow-up at study’s end. This is the first paper to systematically review the literature on follow-up after bariatric surgery.

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