A review of randomized controlled trials (RCTs) in four leading medical journals has revealed that the majority of studies did not use imputation to deal with missing quality of life (QoL) outcome data. The results of this study, conducted at the University of Aberdeen, were published this week in Trials, a BioMed Central journal.

Quality of life outcomes are becoming an increasingly important factor for decision-making in clinical trials of new treatments. Often these outcomes are collected via postal questionnaires and consequently subject to a substantial proportion of missing information. Imputation, whereby a reasonable alternative value is substituted for one that is missing, is one of a range of methods used by researchers to account for missing QoL data and thus try to eliminate potential bias in the results.

Fielding et al. conducted a PubMed search to identify a random selection of 285 RCTs published during 2005 and 2006 in the BMJ, The Lancet, The New England Journal of Medicine and the Journal of the American Medical Association. A QoL outcome was r