Loss to analysis in randomized controlled trials in CKD

Am J Kidney Dis. 2011 Sep;58(3):349-55. doi: 10.1053/j.ajkd.2011.04.023. Epub 2011 Jul 20.


Background: Nephrology has a limited number of randomized controlled trials (RCTs). The quality of randomized trials is compromised further when not all participants randomly assigned are accounted for transparently.

Objectives: Systematically evaluate RCTs in individuals with chronic kidney disease regarding reporting and accounting of data missing in outcome analysis.

Study design: De novo empirical evaluation.

Setting & population: English-language parallel-group design RCTs in adults with chronic kidney disease on dialysis therapy or with a kidney transplant published in MEDLINE in 2007 and 2008.

Outcomes & measurements: (1) How often was there loss to analysis, defined as not all randomly assigned participants included in primary outcome analysis? (2) How often was intention-to-treat analysis complete; in other words, included all randomly assigned participants in their originally allocated group? (3) How often were methods of data imputation reported?

Results: Of 196 eligible RCTs, 27% did not clearly describe a primary outcome, 5% did not provide numbers of patients randomly assigned and analyzed, and 12% used time-to-event analysis. Of the remaining 110 studies, 58% had some loss to analysis, with a median loss to analysis of 10%. Fifty-four percent of trials claimed to have performed an intention-to-treat analysis, but only 44% of those included all participants randomly assigned. Only 5 of 110 (5%) studies mentioned imputation of missing data.

Limitations: Evaluation is restricted to analysis of primary study outcome. Only English-language publications were included. Exclusion of time-to-event analyses.

Conclusions: In variance to the reporting standards of CONSORT (Consolidated Standards of Reporting Trials), we found primary outcome designation missing in one-fourth of trials and poor quality in reporting and accounting of primary outcome data lost to analysis. Greater attention to transparency in handling and reporting loss to analysis will enhance the quality of trials in individuals with chronic kidney disease.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Humans
  • Intention to Treat Analysis / standards
  • Nephrology
  • Outcome Assessment, Health Care / standards*
  • Periodicals as Topic / statistics & numerical data
  • Randomized Controlled Trials as Topic / standards*
  • Renal Insufficiency, Chronic / therapy*