1. Greenhalgh J (2009) The applications of PROs in clinical practice: what are they, do they work, and why? Qual Life Res 18:115–123
2. Jaeschke R, Guyatt G (1990) How to develop and validate a new quality of life instrument. In: Spilker B (ed) Quality of life assessments in clinical trials. Raven Press, New York, pp 47–57
3. US Department of Health and Human Services. Food and Drug Administration. Center for Drug Evaluation and Research (CDER). Center for Biologics Evaluation and Research (CBER). Center for Devices and Radiological Health (CDRH) (2009) Guidance for industry. Patient-reported outcome measures: use in medical product development to support labeling claims [Internet]. Available from http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM193282.pdf
4. Streiner D, Norman G (2008) Health measurement scales: a practical guide to their development and use. Oxford University Press, Oxford
5. Copay AG, Subach BR, Glassman SD, Polly DW, Schuler TC (2007) Understanding the minimum clinically important difference: a review of concepts and methods. Spine J 7:541–546