A psychophysical methodology for the development of measurement scales: the quantification of the qualities of cancer pain

Abstract

The studies in this project demonstrate how the psychophysical methodology can be applied to the measurement of cancer pain to produce a scale which: (1) is based on the descriptors of pain used by cancer patients and the clinicians who treat them, (2) reliably measures patients' subjective experience of pain, (3) is a valid instrument for tracking the effects of treatment, and (4) discriminates the unique characteristics of pain experienced by patients with different pain etiologies. Unlike other pain scales (Melzak & Torgerson, 1971; Hunter, M., 1983; Daut, Cleeland and Flanery, 1983) the scale developed using the psychophysical methodology relied on interviews with cancer pain experts (pain patients and clinicians) to determine what dimensions of pain were important and to identify the descriptors patients use to describe these dimensions. Based on the descriptions of pain obtained in these interviews, the M. D. Anderson Cancer Pain Scale was constructed to measure pain qualities, pain intensity and the disruption of patients' lifestyle. Reliability was demonstrated by showing that patients' responses on the scale were consistent on two similar measurement occasions. Validity was demonstrated by showing the scale's ability to track a known effective treatment and by its ability to discriminate between patients with different pain etiologies.