Comparison of Ventilator-free Days at 14 and 28 days as a Clinical Trial Outcome in Low- and Middle-income Countries.

Abstract

Aims and objectivesReporting ventilator-free days (VFDs) with time frame of 28 days is a popular composite outcome measure (COM) in trials. However, early deaths and shorter pediatric intensive care unit (PICU) stay predominate in low- and middle-income countries (LMICs). A shorter time frame may reduce sample size required. We planned to compute sample size requirements for different effect sizes from datasets of previously conducted prospective studies for 28-day and 14-day time frames (VFD28 vs VFD14) to examine the hypothesis.Materials and methodsThe VFD28 and VFD14 were defined. Datasets of five prospective studies from PICU of our hospital were analyzed to estimate sample sizes for target reductions of 1–9 days in VFDs and other COMs for the two time frames. Reconfirmation of results was done with datasets of two other studies from PICUs of two geographical extremes of the country.ResultsTime-to-event occurred within 14 days in majority of patients. Sample size required for VFD14 is about one-fifth to one-sixth of what is required for VFD28 for target reductions of 1–9 days for all the enrolled studies. The same was true for other COMs as well. The hypothesis was supported by datasets of two other studies used for reconfirmation.ConclusionChoice of time frame for assessing VFDs and other COMs in clinical trials should be guided by the clinical context. A shorter time frame may be rewarding in terms of smaller sample size in the prevalent clinical setting of LMICs. Further confirmation with more datasets and prospective studies is desirable.How to cite this articleBaranwal AK, Kumar MP, Gupta PK. Comparison of Ventilator-free Days at 14 and 28 days as a Clinical Trial Outcome in Low- and Middle-income Countries. Indian J Crit Care Med 2020;24(10):960–966.