Continuous Visual Analog Scale Research Articles

Visual analogue scales for mode-independent measurement in self-administered questionnaires

Previous research has shown evidence for mode differences between computer-assisted self-administered interviews (CASI) and paper-and-pencil interviews, especially in the case of sensitive questions. Some of these differences are explained by higher degrees of self-disclosure for CASI than for paper-and-pencil interviews, due to the more private situation with CASIs. This analysis examines the existence of different degrees of self-disclosure for CASI versus paper-and-pencil questionnaires and whether these differences can be reduced by the use of a specific response format. Judgments of items on a self-control scale with discrete 5-point (Likert-type) scales are compared with judgments on continuous visual analogue scales (VAS). Because a categorization effect for Likert-type items is assumed when pressure for social desirability is present, it is hypothesized that VAS compared to Likert-type response formats are less sensitive to mode differences.

Softer, Higher-Friction Flooring Improves Gait of Cows With and Without Sole Ulcers

We studied dairy cows (n=30) walking on concrete and on a soft, high-friction composite rubber surface to examine how flooring influenced gait and how this differed for cows with hoof lesions. Cows had hooves trimmed 9 wk after the trial and were classified as either with or without sole ulcers. Video recordings of the cows while walking were digitized using motion analysis software to calculate stride variables (length, height, overlap, duration, proportion of triple support, and speed). Gait was scored by a subjective scoring system (1 = sound to 5 = severely lame) and by a continuous visual analog scale for each of 7 gait attributes. Cows with sole ulcers walking on a composite rubber surface had longer strides (156.9±2.6 vs. 149.6±2.6cm), higher stride heights (9.7±0.3 vs. 8.8±0.3cm), more stride overlap (0.4±2.0 vs. −4.3±2.0cm), shorter periods of triple support (3 legs in ground contact; 68.6±2.0 vs. 73.8±2.0%), walked faster (1.22±0.04 vs. 1.17±0.04 m/s) and had lower overall gait scores (2.9±0.1 vs. 3.1±0.1), better tracking-up (19±2 vs. 24±2), better joint flexion (29±2 vs. 33±2), more symmetric steps (31±3 vs. 36±3), and less reluctance to bear weight on their legs (12±2 vs. 16±2) compared with walking on concrete. Similar results were found for cows without sole ulcers. Most of the subjective gait measures could distinguish between cows with and without sole ulcers, but this was not the case for kinematic measures other than stride height. Cows with higher gait scores (more severe lameness) showed the greatest improvement in stride length (r=−0.51), triple support (r=0.59), swing duration (r=−0.44), overall gait score (r=0.46), and reluctance to bear weight (r=0.66) when walking on the rubber surface compared with cows with lower gait scores. These results indicate that rubber flooring provides a more secure footing and is more comfortable to walk on, especially for lame cattle.

Effects of Milking on Dairy Cow Gait

We studied cows with (n=6) and without (n=26) sole ulcers before and after milking to explore how milking influences dairy cattle gait and how this differs for cows with hoof injuries. Video recordings of cows were digitized using motion-analysis software to calculate stride variables for each hoof. Gait was scored using a 1-to-5 numerical rating system (1 = sound, 5 = severely lame) and a continuous 100-unit visual analog scale of gait attributes (back arch, head bob, tracking-up, and reluctance to bear weight). For cows with and without sole ulcers, differences in gait before and after milking were evident; after milking, all cows had significantly longer strides (123.3 vs. 133.5±2.0cm, respectively), higher stride height (8.3 vs. 8.9±0.1cm), shorter stride durations (1.49 vs. 1.41±0.03s), walked faster (0.85 vs. 0.97±0.03 m/s), and had shorter periods of triple support (3 legs in ground contact; 80.0 vs. 71.7±2.0%). Tracking-up and reluctance to bear weight improved after milking (20 vs. 16±2; 20 vs. 15±1, respectively), but numerical rating scores and back arch did not. Cows with sole ulcers walked differently than cows without for all measures, except swing duration, both before and after milking. Interactions between hoof health and milking were found for swing duration and head bob but when tested separately, the only effect was that cows without sole ulcers had longer swing durations before milking (0.45 vs. 0.44±0.01s, respectively). Gait differences were probably due to udder distention and motivation to return to the home pen. Our results suggest that the most suitable time to assess lameness is after milking when differences between cows with and without ulcers are most evident.

Influence of Pharmacists??? Attitudes on Adverse Drug Reaction Reporting

Pharmacists can play a fundamental role in adverse drug reaction (ADR) reporting, although the factors that affect underreporting among these professionals are unknown. The objectives of this study were to identify (i) professional or demographic characteristics; and (ii) attitudes associated with pharmacists' ADR reporting in northern Portugal. We conducted a case-control study on a population of pharmacists employed in hospital and community pharmacies across Portugal's Northern Regional Health Authority catchment area in 2003. Cases (n=34) comprised pharmacists who had reported at least one ADR to the northern region's drug surveillance unit, and controls (n=280) were randomly sampled from pharmacists who had never reported an ADR. All were interviewed using a mail questionnaire. Most attitudes were based on Inman's 'seven deadly sins' and were measured using a continuous visual analogue scale. Answers were recorded in a range from 0 (total disagreement) to 10 (total agreement). Logistic regression was used to determine the ADR reporting adjusted odds ratio (OR) for a change in exposure corresponding to the interquartile range for each attitude. The response rate was 86.8%. Reporting probability proved higher among hospital versus community pharmacists (adjusted OR 20.0; 95 CI 3.3, 125.0; p<0.001). Attitudes to ADRs were strongly associated with reporting probability. Hence, an interquartile decrease in any of the following attitudes increased the probability of reporting by (i) 223% (95% CI 51, 595; p < 0.05) for "Really serious ADRs are well documented by the time a drug is marketed"; (ii) 240% (95% CI 89, 508; p=0.002) for "I would only report an ADR if I were sure that it was related to the use of a particular drug"; (iii) 316% (95% CI 44, 1104; p=0.010) for "It is only necessary to report serious or unexpected ADRs"; and (iv) 171% (95% CI 13, 549; p=0.020) for "I do not have time to think about the involvement of the drug or other causes in ADRs". ADR under-reporting is strongly associated with certain attitudes, possibly indicating that under-reporting could be minimised through educational interventions targeted at changing such attitudes. Pharmacists' ADR education must be improved and educational programmes should be focused on altering attitudes identified by the study as being associated with under-reporting. Our data also indicate that community pharmacists must be a priority target for this intervention.

Effect of Hoof Pathologies on Subjective Assessments of Dairy Cow Gait

To explore how hoof pathologies affect dairy cattle gait, we studied cows with sole hemorrhages (n = 14), sole ulcers (n = 7), and those with no visible injuries (n = 17). Overall gait assessments, scored from video using a 1 to 5 numerical rating system (1 = sound, 5 = severely lame) and a continuous 100-unit visual analog scale, found cows having sole ulcers had poorer gait than healthy cows (mean±SEM: 4.0±0.13 vs. 3.1±0.08, and 59±3 vs. 46±2, respectively). Six gait attributes (back arch, head bob, tracking-up, joint flexion, asymmetric gait, and reluctance to bear weight) were also assessed using continuous 100-unit scales. Compared with healthy cows, those having sole ulcers walked with a more pronounced back arch (12±3 vs. 28±4), more jerky head movement (2±2 vs. 10±3), shortened strides (7±2 vs. 26±4), and more uneven weighting among the limbs (16±2 vs. 32±3). Of all measures, the numerical rating system most effectively discriminated healthy cows from those with sole ulcers (R2 = 0.73), classifying 92% of animals correctly. No differences were detected among cows with and without sole hemorrhages. Intra- and interobserver reliabilities were reasonable for all measures (R2≥0.64) except joint flexion and asymmetric gait. In summary, subjective assessments of dairy cattle gait provide valid and reliable approaches to identifying cattle with sole ulcers.

Enhanced temporal summation of pressure pain in the trapezius muscle after delayed onset muscle soreness

Temporal summation of muscle pain is an important factor in musculoskeletal pain as central integration of repetitive nociceptive input can be facilitated in musculoskeletal pain patients. The aim of this study is to evaluate changes in temporal summation of pressure pain after induction of delayed onset muscle soreness (DOMS) of the trapezius muscle. Sixteen healthy volunteers participated in the study. Temporal summation of pain was induced by sequential pressure stimulation by a computer-controlled algometer. Sequential stimulation consisting of ten stimuli (at pressure pain threshold intensity) was applied over the trapezius muscle. Stimulus duration was 1 s and inter-stimulus intervals (ISI) were 1, 5, 10, and 30 s, respectively. The pain was rated on a continuous visual analogue scale (VAS, 10 cm) after each stimulus and normalised to the VAS score from the first stimulus. DOMS was induced in the right trapezius muscle by eccentric shoulder exercises while the left trapezius muscle served as control. Temporal summation of pressure evoked pain was measured before and 24 h after the exercise. At 24 h after exercise, soreness intensity during shoulder elevation was 3.7+/-0.2 cm, while no soreness was observed on the control side. When sequential pressure stimulation was applied to the DOMS muscle, VAS scores for 1 s ISI progressively increased to a higher level than before exercise (VAS increase for the last stimulus: 0.8+/-0.2 cm vs. 0.6+/-0.1 cm, P<0.05), while VAS scores for ISI 5, 10, and 30 s were not increased. On the control side, significant increases in VAS scores was observed for all ISIs but not affected by contralateral DOMS. Facilitation of temporal summation for 1 s ISI indicated that DOMS may increase the central excitability besides involving peripheral sensitisation. During DOMS there was no potential for further nociceptor sensitisation by repeated noxious pressure stimuli, which may account for the diminishment of temporal summation evoked by pressure stimuli with ISI 5, 10, and 30 s. These data indicate that muscle soreness might facilitate the central components of temporal summation to mechanical stimulation.

Changes in Mechanical, Chemical, and Thermal Sensitivity of the Cornea after Topical Application of Nonsteroidal Anti-inflammatory Drugs

In addition to their well-known anti-inflammatory actions, some of the nonsteroidal anti-inflammatory drugs (NSAIDs) appear to have an analgesic effect. In human subjects, the changes in threshold and intensity of sensations evoked by mechanical, chemical, and thermal stimulation of the cornea induced by topical administration of two commercial NSAIDs, diclofenac sodium (Voltaren; Novartis, Basel, Switzerland) and flurbiprofen (Ocuflur; Allergan, Irvine, CA), were studied. Corneal sensitivity was measured in 10 young, healthy subjects with a gas esthesiometer. Chemical (10%-70% CO2 in air), mechanical (0-264 mL/min), and thermal (corneal temperature changes between -4.5 degrees C and +3 degrees C around the normal value) stimuli were applied to the center of the cornea. The intensity and perceived magnitude of the psychophysical attributes of the evoked sensation were scored at the end of the pulse in a 10-cm, continuous visual analog scale (VAS). The threshold was expressed as the stimulus intensity that evoked a VAS score >0.5. Sensitivity was measured in both eyes of each subject on two separate days, one without treatment and the other 30 minutes after topical application of 0.03% flurbiprofen (seven subjects) or 0.1% diclofenac sodium (six subjects). Diclofenac attenuated significantly all the sensation parameters evoked by high-intensity mechanical, chemical, and thermal stimuli. Flurbiprofen produced a slight reduction of the sensations evoked by mechanical and chemical stimulation that became significant only for the irritation caused by chemical stimuli of maximum intensity (70% CO2). None of the drugs modified significantly the detection threshold of the different stimuli. Flurbiprofen had a very limited effect on sensations evoked by corneal stimulation, whereas diclofenac reduced the intensity of sensations evoked by stimuli of different modality, suggesting a mild local anesthetic effect of this drug on all types of corneal sensory fibers. Such anesthetic action could explain the analgesic effect that has been reported after topical application of diclofenac in inflamed human eyes.

Physicians??? Attitudes and Adverse Drug Reaction Reporting

Voluntary adverse drug reaction (ADR) reporting is fundamental to medical drug safety surveillance; however, substantial under-reporting exists and is the main limitation of the system. This study sought to identify the knowledge- and attitude-related factors associated with ADR reporting by physicians in Northern Portugal. Case-control study covering a population of National Health Service medical practitioners. The 88 cases comprised physicians who had reported at least one ADR to the drug surveillance unit from the year 2000 to the date of enrolment in the study. The 771 controls were randomly selected from among the remaining physicians. All interviews were conducted using a self-administered questionnaire. Knowledge and attitudes regarding spontaneous ADR reporting were based on Inman's 'seven deadly sins'. Agreement with the questions included in the questionnaire was measured using a horizontal, continuous visual analogue scale, which was unnumbered. Recorded answers were read in a range from zero (total disagreement) to ten (total agreement). We used logistic regression to determine the ADR reporting adjusted odds ratio (ORadj) for a change in exposure corresponding to the interquartile range for each attitude. A total of 397 questionnaires were received from 731 eligible practitioners (54.3%). Physicians who worked in primary versus hospital care (ORadj 7.74 [95% CI 1.85, 32.30]) and in general medicine (ORadj 1.05 [95% CI 0.30, 3.69]) versus medical specialities were more likely to report ADRs. In contrast, physicians working in the medical-surgical/surgical fields were significantly less likely to report ADRs compared with medical specialists (ORadj 0.10 [95% CI 0.02, 0.46]). Attitudes to ADRs were strongly associated with reporting probability. Hence, an interquartile decrease in any of the following attitudes increased the probability of reporting by: (i) 87% (p < 0.05) for complacency (the belief that really serious ADRs are well documented by the time a drug is marketed); (ii) 109% (p < 0.01) for insecurity (the belief that it is nearly impossible to determine whether a drug is responsible for a particular adverse reaction); (iii) 143% (p < 0.001) for diffidence (the belief that one would only report an ADR if one were sure that it was related to the use of a particular drug); (iv) 220% (p < 0.001) for indifference (the belief that the one case an individual doctor might see could not contribute to medical knowledge); and (v) 71% (p < 0.05) for ignorance (the belief that it is only necessary to report serious or unexpected ADRs). This study shows that there are attitudes strongly associated with under-reporting. The implementation of purpose-designed educational interventions based on the attitudes identified in this study may serve to improve reporting substantially.

Accuracy and validity of observational estimates of shoulder and elbow posture

This study investigated the accuracy of video-based observational posture analysis for the elbow and shoulder. Posture analyses were conducted by 28 ergonomists for four jobs presented on a traditional VHS format video recording. Estimates of posture from the observational-based methods were compared with values measured directly with an optical motion capture system. Ergonomists used categorical posture scales and a continuous visual analog scale to estimate the peak and most frequently occurring or average posture for each job. Use of a three-category scale resulted in misclassifications of peak and most frequently occurring elbow and shoulder posture with a probability averaging 30.1%. With the six-category posture scale this average probability of misclassification increased to 64.9%. Using a continuous visual analog scale peak shoulder elevation was the only posture for which the average error among ergonomists’ estimates was significantly different from zero ( p<0.05). Correlations between the estimated postures and measured postures were higher and statistically significant ( p<0.05) for elbow flexion and shoulder elevation ( r 2 between 0.45 and 0.66) but were considerably lower and not significant ( r 2 between 0.03 and 0.18) for the peak and average horizontal shoulder abduction. Ergonomists’ estimates of the temporal distribution of shoulder posture, indicating the duration severity of the posture, appeared to be biased such that the percentage of the cycle time in each posture category was estimated as more uniformly distributed than the measured values indicated.

Visceral and cutaneous hypersensitivity in Persian Gulf war veterans with chronic gastrointestinal symptoms

Approximately 697,000 United States military personnel participated in the Persian Gulf War (PGW) between August 1990 and March 1991. By April 1997, over 25% of veterans reported chronic health complaints of underdetermined etiology. Gastrointestinal symptoms were among the most frequently reported symptoms including abdominal pain and diarrhea. The objectives of this study were (1) to determine if PGW veterans chronic abdominal pain and diarrhea exhibit visceral and cutaneous hypersensitivity, (2) to determine if these differences in pain sensitivity are significantly associated with psychological stress. A total of 12 veterans (ten males, two females) (39±9 years) who were deployed to the Persian Gulf were enrolled. Seven civilians without prior military experience (five males, two females) and five veterans (five males) who had previously been deployed for active combat were enrolled as controls (35±9 years). All 12 PGW veterans reported chronic abdominal pain and diarrhea (negative diagnostic workup) that developed during their tour of duty in the Persian Gulf region. All patients completed a battery of psychological assessments and then randomly received experimental visceral (rectal distension of 35 and 55 mmHg for 30 s) and cutaneous (immersion of right foot in 45 and 47°C water for 30 s) pain stimuli after which they rated their pain intensity and pain unpleasantness on a continuous visual analogue scale (M-VAS) scale. The trials were repeated and the mean M-VAS scores for the two trials were recorded for each subject. In comparison to controls, PGW subjects reported statistically significant higher mean ratings of pain intensity and pain unpleasantness in response to 35 and 55 mmHg rectal distention ( P<0.001) and in response to 45 and 47°C water immersion ( P<0.001) of the hand and foot. Results of the hierarchical regressions indicated that the psychological measures (i.e. anxiety, somatic focus) accounted for a significant amount of variance in each of the pain measures. PGW veterans who developed chronic abdominal pain and diarrhea during their tour of duty exhibit visceral hypersensitivity similar to patients with the irritable bowel syndrome. These veterans also have cutaneous hypersensitivity and higher levels of anxiety and somatic focus accounting for these differences in pain reporting.

Reduction of TMD pain by high-frequency vibration: a spatial and temporal analysis

Under some conditions, vibration delivered to the skin can reduce pain ( vibratory analgesia). Previous studies of this phenomenon in a clinical context have been somewhat variable in terms of stimulus control, and have not examined the way in which the spatial distribution of pain is affected. In the present study, we used rigorously controlled conditions to examine vibratory analgesia in participants ( N=17) with painful temporomandibular disorders (TMD). Results of 20- and 100-Hz vibration were compared with data from a no-vibration control condition. The results document for the first time that vibratory analgesia occurs in TMD chronic pain conditions. We measured its time course using continuous visual analog scale (VAS) recording, and its spatial aspects by asking subjects to indicate painful regions on standardized drawings. VAS ratings and drawings both showed that pain is reduced by 100-Hz, but not by 20-Hz, vibration. The effectiveness of the high-frequency vibration cannot be attributed to a mechanism involving Pacinian corpuscles, since these receptors are lacking in the skin of the orofacial region. Spatial analyses revealed that ipsilateral and contralateral effects of vibration were statistically equivalent, suggesting that vibratory analgesia relies at least in part on central nervous system processes rather than local mechanisms.

Effect of cue exposure, urge to smoke, and nicotine deprivation on cognitive performance in smokers.

The primary aim of this investigation was to test the hypothesis that the urge to smoke interferes directly with cognitive performance. Fifty-four smokers were randomly assigned to 1 of 3 groups: (a). ad lib, (b). deprived, or (c). nicotine patch. Participants rated their urge to smoke on continuous visual analogue scales. Cognitive performance was determined by measuring reaction times (RTs) on a Sternberg task. The deprived group reported a higher urge and had longer RTs than the ad lib group when exposed to smoking-related cues. However, the nicotine patch group reported a higher urge in the absence of longer RTs. The results indicated that nicotine deprivation affects cognitive performance and that the urge to smoke only partially mediated RTs.

Generalised muscular hyperalgesia in chronic whiplash syndrome

The whiplash syndrome has immense socio-economic impact. Despite extensive studies over the past years, the mechanisms involved in maintaining the pain in chronic whiplash patients are poorly understood. The aim of the present experimental study was to examine the muscular sensibility in areas within and outside the region involved in the whiplash trauma. Eleven chronic whiplash patients and 11 sex and age matched control subjects were included in the study. Before the experiment, the whiplash patients had pain in the neck and shoulder region with radiating pain to the arm. Five patients reported pain that was more widespread. The somatosensory sensibility in the areas over the infraspinatus, brachioradial, and anterior tibial muscles was assessed by pressure stimulation, pin-prick stimulation, and cotton swap stimulation. Infusion of hypertonic saline (5.85%, 0.5 ml) into the infraspinatus and anterior tibial muscles was performed to assess the muscular sensibility and referred pain pattern. The saline-induced muscle pain intensity was assessed on a continuous visual analogue scale (VAS). The distribution of pain was drawn on an anatomical map. The pressure pain thresholds were significantly lower in patients ( P<0.01) compared with controls: infraspinatus (mean 152.2 vs. 172.7 kPa), brachioradial (mean 70.0 vs. 363.8 kPa), and anterior tibial muscle (mean 172.7 vs. 497.8 kPa). The skin sensibility to pin-prick stimulation and cotton swap stimulation was not different between patients and controls. Infusion of hypertonic saline caused significantly higher VAS scores with longer duration in patients compared to control subjects ( P<0.01). The area under the VAS-time curve was significantly ( P<0.01) increased in patients compared to control subjects after injection into the infraspinatus muscle (mean 4138.1 vs. 780.0 cm s) and anterior tibial muscle (mean 4370.8 vs. 978.7 cm s). The saline infusion caused local pain defined as pain located around the injection site and referred pain areas not included in the local pain area. The area of local and referred pain were significantly larger in patients compared to control subjects ( P<0.01). In the control group, the referred pain areas to infusion of hypertonic saline into the anterior tibial muscle were found at the dorsal aspect of the ankle. In contrast, the areas of referred pain were quite widespread in the patient group with both distal and proximal referred pain areas. In the present study, muscular hyperalgesia and large referred pain areas were found in patients with chronic whiplash syndrome compared to control subjects both within and outside the traumatised area. The findings suggest a generalised central hyperexcitability in patients suffering from chronic whiplash syndrome. This indicates that the pain might be considered as a neurogenic type of pain, and new pharmacological treatments should be investigated accordingly.

Studies with pain rating scales.

Good correlation has been shown between pain scores derived from 4 different rating scales. The correlation was maintained when presentation of the scales was separated by a series of questions and by physical examination. There is good evidence that the 4 scales are measuring the same underlying pain variable as they calibrate well. There is also evidence that an 11-point (0-10) numerical rating scale performs better than both a 4-point simple descriptive scale or a continuous (visual analogue) scale.