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Comment & Response
May 23, 2018

Considerations When Calculating Data Completeness

Author Affiliations
  • 1Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania
  • 2Department of Biostatistics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania
  • 3Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
JAMA Surg. Published online May 23, 2018. doi:10.1001/jamasurg.2018.1159

To the Editor We agree with Higa and Himpens1 that obtaining long-term data following metabolic/bariatric surgery is a challenge and that appropriate analytical methods need to be used to account for missing data, although they are not a substitute for complete follow-up. However, we disagree with their characterization of 7-year data completeness in the Longitudinal Assessment of Bariatric Surgery (LABS) study.2 Higa and Himpens stated, “data at 7 years were available for 1300 of the eligible 2277 patients (57%), not the 82.9% rate as reported.”1 They determined their percentage by dividing the number of nonpregnant participants with 7-year weight data (n = 1300) by the number of participants at study entry (n = 2348) minus the number who died prior to year 7 (n = 71). However, as the article indicates, the study ended before 700 participants were due for the 7-year assessment.2 Thus, it is inappropriate to include them in the denominator when calculating 7-year data completeness. Furthermore, because weights of pregnant women were excluded from the report, pregnant women (n = 9 at year 7) should not be counted in the denominator either.

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