Analog Scale Patient Research Articles

The Linearity of the Visual Analogue Scale in Patients with Severe Acute Pain

The visual analogue scale (VAS) is a standard measurement tool in pain research and clinical practice, and has been shown to have linear scale properties for mild to moderate pain. Our aim was to evaluate the scaling properties of the VAS in subjects with severe acute pain. After Ethics Committee approval we studied 22 patients and asked them to rate the severity of their pain on a 100 mm VAS at the initial assessment (VAS1), and again after administration of analgesic medication. The subject was asked to nominate when they considered their pain intensity had halved, and at this time they were asked to rate this on a second VAS (VAS0.5). When the subject had received satisfactory relief of their pain, they were asked to describe how much their pain had been relieved and were then asked to rate their final pain state using a third VAS (VASfinal). The mean (SD) scores were VAS1 84 (14) (range 56-100), VAS0.5 42 (13) and VASfinal 21 (16). The mean (95% CI) for VASratio was 0.51 (0.45-0.57). The mean (SD) patients' estimate of pain relief was 77 (21)% from that of baseline, with a mean (SD) VASfinal 0.26 (0.20), 95% CI 0.17-0.38. The correlation of the patients' estimate of pain relief with the VASfinal was r=0.89, rho=0.87, both P<0.001. The VAS is a linear scale in subjects with severe acute pain. Changes in the VAS score represent a relative change in the magnitude of pain sensation.

Clinically significant changes in nausea as measured on a visual analog scale

Our objective is to determine the minimum clinically significant change in nausea as measured on a visual analog scale. This was a prospective, descriptive, convenience sample study of consenting adults presenting to the emergency department with nausea, excluding intoxicated patients and those with mild nausea (measuring <30 mm on a visual analog scale). Patients rated their nausea severity on a 100-mm visual analog scale and reported whether their nausea was "a lot less," "a little less," "unchanged," "a little more," or "a lot more" compared with previous assessments. We defined the minimum clinically significant change as the mean difference in visual analog scale in patients reporting "a little less" or "a little more" nausea. Eighty-three paired visual analog scale measurements were collected from 50 patients. Fifty-eight percent of patients were women, and the mean age was 41 years. Mean changes in visual analog scale with corresponding qualitative descriptors were "a lot less" in 16 paired measurements (-42.2 mm; 95% confidence interval [CI] -54.9 to -29.5); "a little less" in 34 paired measurements (-15.4 mm; 95% CI -20.0 to -10.8); "no change" in 28 paired measurements (-0.4 mm; 95% CI -5.6 to 4.8); "a little more" in 2 paired measurements (16 mm; 95% CI -86 to 118); and "a lot more" in 3 paired measurements (23.7 mm; 95% CI -5.4 to 52.8). Patients reported "a little more" or "a little less" nausea in 36 paired measurements, with a mean change in visual analog scale of 15.4 mm (95% CI 11.0 to 19.8). The minimum clinically significant visual analog scale change in nausea was 15 mm, which is similar to previous studies of other symptoms, and helps in the interpretation of clinical studies reporting changes in nausea.

Perceived effect on shortness of breath of an acute inhalation of saline or terbutaline: variability and sensitivity of a visual analogue scale in patients with asthma or COPD

The purpose of the study was to validate a bipolar visual analogue scale (VAS) to assess the perceived effect on shortness of breath of an acute inhalation and to search for differences in perception between asthmatics and subjects with chronic obstructive pulmonary disease (COPD). Thirty two subjects with airway obstruction and a diagnosis of either asthma (n = 16) or COPD (n = 16) received three consecutive inhalations of isotonic saline, followed by two inhalations of 400 micrograms terbutaline. Saline was perceived by asthmatics as a slight improvement: VAS (median, 95% confidence interval) 9%, 0-18% of line length. COPD subjects could be separated into two subgroups: "high perceivers" (n = 8, VAS 43%, 33-53%) and "low perceivers" (n = 8, VAS 5%, 3-7%). The median intrasubject coefficient of variation of the three post-saline VAS ratings was 19.4% (asthma), 12.5% (COPD high perceivers), and 14.5% (COPD low perceivers). After terbutaline, asthmatics had, by selection, a larger increase in forced expiratory volume in one second (FEV1) than COPD subjects. However, for other indices (expiratory specific resistance, inspiratory vital capacity and maximal inspiratory flow at 50% forced vital capacity) the changes were smaller in COPD low perceivers than in both asthmatics and COPD high perceivers. The parallel improvement in VAS was 24%, 20-39% (asthma), 15%, 6-25% (COPD high perceivers) and 1%, -1-8% (COPD low perceivers). The most sensitive index was FEV1 in asthmatics, vital capacity in COPD subjects, VAS being among the most sensitive indices in the former, but among the least sensitive in the latter. We conclude that the sensitivity of this VAS to bronchodilation is better in asthmatics than in COPD subjects. The latter can however be separated into subgroups with high and low level of perception.