Prevention and management of missing data during conduct of a clinical study

In a clinical study missing data can occur for various reasons, with or without any actual loss of study participants because of drop-outs. Poorly designed assessment schedules or use of inefficient data collection tools can result in missed visits or omissions of questions and, thus, missing data. Some simple adjustments in the assessment schedule or minor modifications in the data collection tools can reduce these types of problems and, at the same time, reduce participants’ burden and inconvenience. If implemented properly, an efficient missing data monitoring system can retrospectively salvage the majority of the missing data items except those that are the result of the drop-out of participants. The effectiveness of such a monitoring system depends on how quickly the missing data items are identified and how promptly participating site personnel are notified of the need to provide missing information.