Theoretical, psychometric, and pragmatic issues in pain measurement.

Measurement is essential to nursing practice and research, and adequate tool selection is crucial for both. The present paper seeks to provide an overview of key issues to consider in tool development, selection, and psychometric testing using the concept of pain. Both the classic and the contemporary approaches to validity are described and compared. Although sharing similar features, the contemporary approach seems more encompassing, because it considers measurement purposes, participants' characteristics, and conditions under which instruments are used. Strategies pertaining to reliability and validity testing are discussed and illustrated with specific pain assessment measures, including pain intensity scales, multidimensional questionnaires, and other behavioral tools. Depending on measurement purposes, the more appropriate strategies are highlighted. Cultural issues in pain measurement as well as pragmatic criteria for measure selection also are discussed.