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. 2022 Aug 15;13:189–197. doi: 10.2147/PROM.S371882

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© 2022 Cella and Hays.

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Valderas and Alonso (2008) proposed classification system.

Note: Reprinted by permission from Springer: Quality of Life Research, Patient reported outcome measures: a model-based classification system for research and clinical practice. Valderas JM, Alonso J. 2008;17:1125-1135.13