Can patients accurately read a visual analog pain scale?

The objective of this study was too determine if patients can accurately read a visual analog scale (VAS) for pain. A 100-mm visual analog pain scale designed for patient use was printed on the top page of carbonless copy paper with a perfectly aligned hatched scale on the second (bottom) page. Patients over the age of 18 in acute pain were enrolled in this prospective, descriptive study. Patients were asked demographic questions and to indicate their pain severity with a single mark through the 100-mm scale. Once scored, patients were asked to read the number from the hatched bottom scale. Two physician-raters, blinded to patients' and each other's readings, then scored the VAS. Analysis of physician interrater reliability and correlation of patient and physician readings was performed. One hundred forty-five patients were enrolled. Seventy-nine patients (54.5%) read the VAS exactly as physician-readers. One hundred thirty-eight (95.2%) read their VAS within +/-2 mm of physician readings. Ninety-five percent of patients are able to read a VAS within +/-2 mm of physician readings. The data suggests this instrument could be used by discharged patients in longitudinal pain studies or with help in management of chronic pain.