The descriptor differential scale of pain intensity: an evaluation of item and scale properties

Improved methods for pain measurement have both theoretical and clinical importance. This study evaluated the Descriptor Differential Scale (DDS) of Pain Intensity, a recent methodology designed for assessing pain reports in clinical samples. Experiment 1 evaluated the sensitivity of the measure to small changes in electrocutaneous stimulation relative to a traditional visual analogue scale (VAS) of pain intensity. Additionally, direct psychophysical scaling methods were employed to determine ratio-scale values for the DDS sensory items in relation to the electrocutaneous stimuli. This ratio scale was cross-validated by comparison with previously published ratio-scaled data from cross-modality matching pain intensity judgement studies. Experiment 2 evaluated the performance of the measure in both experimental and clinical pain samples, as well as the similarity of item-response patterns in each of these samples. Results indicate that the DDS of Pain Intensity is sensitive to small changes in electrocutaneous stimulation, has consistent ratio-scale properties across two different psychophysical methods, and demonstrates similar item-response patterns across divergent experimental and clinical samples. The results support the validity of the sensory DDS as a measure of pain intensity.