Visual Analogue Scale Data Research Articles

Impact of Music on Pediatric Oncology Outpatients

Music is widely used to enhance well-being. We wished to assess music's effect on pediatric oncology outpatients. Patients who had leukemia and were in maintenance or consolidation outpatient treatment served as their own control at two visits. At visit 1, children rested for 20 min; at visit 2, for 20 min they listened to music designed to increase vitality and improve heart rate variability (HRV). At both visits, parents completed before and after treatment visual analog scales (VAS) of their child's relaxation, well-being, vitality, anxiety, stress, and depression; patients' heart rates were monitored during treatments to calculate HRV. The 47 patients with complete VAS data and 34 patients with usable HRV data were similar. At baseline, VAS scores for negative states were low (average <2.5 of 10) and positive states were high (average 7> of 10). Relaxation improved more with music than rest (p < 0.01). The HRV parasympathetic parameter was significantly lower with music than rest. No other differences were significant. Further studies are needed to better delineate the relationship between subjective and objective measures of well-being among patients who are not in severe distress.

Effects of Pulsed Electromagnetic Fields on Postoperative Pain: A Double-Blind Randomized Pilot Study in Breast Augmentation Patients

Postoperative pain may be experienced after breast augmentation surgery despite advances in surgical techniques which minimize trauma. The use of pharmacologic analgesics and narcotics may have undesirable side effects that can add to patient morbidity. This study reports the use of a portable and disposable noninvasive pulsed electromagnetic field (PEMF) device in a double-blind, randomized, placebo-controlled pilot study. This study was undertaken to determine if PEMF could provide pain control after breast augmentation. Forty-two healthy females undergoing breast augmentation for aesthetic reasons entered the study. They were separated into three cohorts, one group (n = 14) received bilateral PEMF treatment, the second group (n = 14) received bilateral sham devices, and in the third group (n = 14) one of the breasts had an active device and the other a sham device. A total of 80 breasts were available for final analysis. Postoperative pain data were obtained using a visual analog scale (VAS) and pain recordings were obtained twice daily through postoperative day (POD) 7. Postoperative analgesic medication use was also followed. VAS data showed that pain had decreased in the active cohort by nearly a factor of three times that for the sham cohort by POD 3 (p < 0.001), and persisted at this level to POD 7. Patient use of postoperative pain medication correspondingly also decreased nearly three times faster in the active versus the sham cohorts by POD 3 (p < 0.001). Pulsed electromagnetic field therapy, adjunctive to standard of care, can provide pain control with a noninvasive modality and reduce morbidity due to pain medication after breast augmentation surgery.

Effect of addition of menthol to a drink on voluntary fluid and carbohydrate intake during exercise in humans.

The purpose of this study was to investigate if the cold sense of menthol facilitates voluntary fluid and carbohydrate (CHO) intake during exercise in humans. Eighteen women's hockey player performed a routine training session were given 3 beverages : water (W), 5% CHO drink (C; 5% CHO, 0.1% citric acid, 0.1% NaCl) and 5% CHOwith menthol drink (MC; 5% CHO, 0.1% citric acid, 0.1% NaCl, 0.1% menthol). The subjects chose these drinks freely during the training and the intake of each drink was measured after the training. The subjects were asked to answer a visual‐analog‐scale (VAS) questionnaire on the feelings on each drink. Although the intake of each drink did not differ significantly, the intake of C and MC tended to be greater than W. The subjects fell into three groups according to their most favorite drink; W (PW, n=3), C (PC, n=7), MC (PMC, n=8). Fluid and CHO intake of PC and PMC was calculated as the sum of the most favorite drink and water. The ratio of water intake was higher in PC than PMC (43.0% (SD 34.9) vs 8.7 (6.1), P &lt; 0.05). Consequently, C was diluted more compared to MC. As a result CHO concentration was PMC &gt; PC (4.6% (SD 0.3) vs 3.6 (0.9) , P &lt; 0.05). VAS data showed that sweetness was stronger in MC and C than W (P &lt; 0.05), and tended to be lower in MC than C. These results suggest that the cold sense of menthol reduces sweetness which would avoid diluting a drink so that larger amount of CHO could be supplied during exercise, which would be beneficial to improve physical performance.

Adherence Analysis Using Visual Analog Scale Versus Claims-Based Estimation

Although visual analog scales (VAS) have been used frequently in outcomes research, there is little evidence regarding the validity of this scale for measuring medication adherence. To determine whether a VAS self-report measure of medication adherence is concordant with claims-based measurement of adherence. A mail survey was conducted in 2005 of persons with diabetes. Prescription claims were obtained for the 1985 survey respondents who used oral diabetes medications and lipid-modifying drugs. The self-reported measure of adherence was a VAS scored 0-100%, and the claims-based measure was the continuous measure of medication gaps (CMG), reverse-coded to yield a score of 0-100%. Dichotomous measures (highly adherent vs poorly adherent) were also created from the VAS and CMG using a cutoff value of 80%. For diabetes and lipid-modifying drugs, the scores on the VAS and CMG (continuous versions) were compared using a Pearson correlation coefficient, while the concordance of the dichotomous versions of the measures was compared using the kappa coefficient. The mean +/- SD for the VAS and CMG for oral diabetes drugs were 95.9 +/- 9.2 and 84.1 +/- 19.2, respectively, and for lipid-modifying drugs, 95.2 +/- 11.2 and 85.3 +/- 20.0, respectively. The VAS-diabetes and CMG-diabetes scales were moderately correlated (r = 0.22), as were the VAS-lipid and CMG-lipid (r = 0.26). The majority (69.0%) of subjects had consistent adherence classifications across the dichotomous versions of VAS-diabetes and CMG-diabetes (kappa = 0.13), while 73.1% of subjects had consistent classifications for the dichotomous VAS-lipid and CMG-lipid (kappa = 0.19). The VAS self-reports of adherence to medications had moderate concordance with estimates derived from drug benefit claims. Although the majority of subjects were consistently classified by the VAS and claims, the concordance may not be sufficient for direct comparisons of studies using VAS data with studies using claims-based estimates.

Intermittent Stimulation Delays Adaptation to Electrocutaneous Sensory Feedback

Electrotactile displays deliver information to the user by means of electrocutaneous stimulation. If such displays are used in prostheses, the functionality depends on long term stability of this information channel. The perceived sensation, however, decays within 15 min due to central adaptation if the stimulation is applied continuously and at constant strength. In this study, the effects of stimulus amplitude and intermittent stimulation on adaptation were investigated in ten healthy subjects. The perceived sensation was recorded during 15 min of constant stimulation using a visual analog scale (VAS). The sensation level with time thus measured were parameterized by the initial sensation level, the time constant of decay and the end sensation level after fitting of an exponential function through the VAS data. The time constant increased significantly when applying a high stimulation level (at 80% of the range between sensation and pain thresholds) if compared with lower levels of stimulation (20% and 50%) during continuous stimulation. Intermittent stimulation at this high stimulation level significantly increased end sensation level.

Free Fatty Acids Have More Potent Effects on Gastric Emptying, Gut Hormones, and Appetite Than Triacylglycerides

The effects of fat on gastric emptying (GE), gut hormones, and energy intake are dependent on digestion to free fatty acids (FFAs). In animals, small intestinal oleic acid inhibits energy intake more potently than the triacylglyceride (TG) triolein, but there is limited information about the comparative effects of FFA and TG in human beings. We compared the effects of FFA and TG on GE, gut hormone secretion, appetite, and energy intake in healthy males. Nine men (age, 23 +/- 2 y; body mass index, 22 +/- 1 kg/m(2)) were studied on 3 occasions to evaluate the effects of (1) 40 g oleic acid (FFA, 1830 kJ), (2) 40 g macadamia oil (TG, 1856 kJ; both 600-mL oil-in-water emulsions stabilized with 4% milk protein and labeled with 15 MBq (123)I), or (3) 600 mL 4% milk protein (control, 352 kJ), administered intragastrically, on GE, plasma cholecystokinin (CCK) and peptide-YY (PYY) levels, appetite perceptions, and subsequent energy intake. GE of FFA was much slower than that of TG (P < .05), with greater retention of FFA, than TG, in the proximal stomach (P < .001). Hunger was less (P < .05), and fullness was greater (P < .05), after FFA when compared with control and TG. Increases in plasma CCK and PYY levels were greater after FFA than TG or control (P < .05). Energy intake tended to be less after FFA compared with TG (control, 4754 +/- 610 kJ; TG, 5463 +/- 662 kJ; FFA, 4199 +/- 410 kJ). FFAs empty from the stomach more slowly, but stimulate CCK and PYY and suppress appetite more potently than TG in healthy human beings.

Electromyography in Evaluation of Pain after Different Types of Tonsillectomy: Prospective Randomized Study

Background: Combined surface electromyography (sEMG) and visual analogue scale (VAS) pain assessment was performed on randomly assigned adults following tonsillectomy to research the effect of fibrin sealant (Group 1, n = 25), CO₂ laser (Group 2, n = 18) and electrocoagulation (Group 3, n = 40) on postsurgical pain. Methods: Timing and amplitude of sEMG activity of masseter, infrahyoid and submandibular muscles were measured during swallowing simultaneously with VAS assessment and compared to normative database. Results: Postsurgical electric activity of masseter and infrahyoid was significantly higher in comparison with normative database. sEMG and VAS data showed that tonsillectomy ended with fibrin sealant caused less pain than laser or electrocoagulation techniques with no correlation between the VAS score and duration of swallows. Conclusion: Tonsillectomy affects muscle activity significantly by involving additional muscles (infrahyoid) in swallowing. Combined sEMG and VAS data indicated electrocautery as the most painful, laser as less painful, and fibrin sealant as the least painful technique.

It might be premature to reject the assumption of a power curve relationship between VAS and SG data: three comments on Stevens, McCabe and Brazier's ‘Mapping between VAS and SG data; results from the UK HUI Index 2 valuation survey’

In a recent paper in Health Economics, Stevens, McCabe and Brazier (Health Econ. 2006; 15: 527-533.) found that the cubic relationship between Visual Analog Scale (VAS) values and standard gamble (SG) utilities was superior to other functional forms in terms of explanatory power and predictive ability. Consequently, they question the reliance on the assumption of a power curve relationship, which was established, theoretically and empirically, in earlier works. This note argues that: (1) SMB's conclusions are incorrect. The estimated cubic function overfits the four data points, and is questionable with respect to the implied attitude toward relative risk. (2) The evaluation of the functional forms in terms of the individual predictions' mean absolute error is misleading and (3) correcting for heteroscedasticity improves the precision of the estimates and of the predictions.

Subjective symptom perceptual accuracy in asthmatic children and their parents in India

Inaccurate symptom perception is a key factor in increased morbidity and mortality in asthmatic patients. Information is sparse on whether children and their parents can accurately perceive severity of symptoms. To determine symptom perceptual accuracy in children with asthma and either of their parents. Fifty-two asthmatic children and either of their parents recorded independently, for 2 weeks, subjective evaluation of the child's symptoms on a 100-mm visual analog scale (VAS). Peak expiratory flow (PEF) was used as an objective measurement. Both VAS and PEF data were graded into green, yellow, and red zones. The 2 sets of VAS zones (children and parents) were separately matched with PEF zones to determine perceptual accuracy. Children and parents were accurate more than half of the time (60% and 62%, respectively), but accuracy decreased when the "child was unstable" (PEF <80% of personal best), with underestimation being significant (P < .001). Among the readings obtained, underestimation of severity of symptoms was significant in children with severe asthma (125 [45%] of 278 readings), those affected by environmental tobacco smoke (130 [24%] of 532), and those in the younger age group (127 [45%] of 280). Underestimation was significantly greater when PEF readings were in the yellow zone (P < .001). Symptom perception by children was as reliable as that by their parents. However, parents and children tended to underestimate severity when the child was unstable. An early decline in PEF readings was missed by children and their parents, which could contribute to increased morbidity and mortality in this vulnerable age group.

Rhinitis Symptom Utility Index (RSUI) in Chinese Subjects: A Multiattribute Patient-preference Approach

The Rhinitis Symptom Utility Index (RSUI), originally developed in the United States, consists of a patient-preference weighting scheme and a 10-item questionnaire measuring the severity and frequency of rhinitis related symptoms over a 14-day period. This study aimed to determine whether the Chinese RSUI could adopt the US-based multi-attribute utility function (MAUF) in scoring rhinitis symptoms. In a Hong Kong study, 116 Chinese adults with allergic rhinitis completed the RSUI questionnaire and 36-item Short-Form Health Survey (SF-36) after they had been seen by two otorhinolaryngologists for disease-severity ratings. Respondents then completed computer-administered direct preference measures, i.e., visual analogue scale (VAS) and standard gamble (SG) assessments. The VAS and SG data were used to estimate a MAUF for the Chinese-based RSUI. The derived MAUF was somewhat different than the one developed for the US RSUI. Test-retest reliability for the Chinese RSUI was satisfactory (ICC = 0.71, p<0.001). Scores differentiated among cases with mild, moderate, and severe symptoms (p<0.001); and between those who did and did not require medications to control symptoms (p = 0.031). Findings were significantly correlated with SF-36 domain scores (r = 0.19 to 0.37; p=0.041 to <0.001). When the US-based scoring function was applied to the Chinese subjects, the resulting mean RSUI score was significantly lower (p<0.001). Comparisons between directly measured VAS and SG scores between the US and Chinese samples, demonstrated significant differences (all p<0.05), with the US subjects consistently rating rhinitis symptoms as worse than Chinese subjects. The Chinese RSUI has good measurement properties that reflect patient preferences from the Chinese. Results suggest that there are differences in preference rating between US and Chinese subjects and that use of the US-based preference function for the RSUI would bias the measurement of rhinitis symptom outcomes in Chinese subjects.

Correlation Between Visual Analog Scale and Pressure Algometry Measures in Assessing Skeletal Muscle Soreness

Muscle soreness following strenuous exercise is a common finding and has been studied extensively in relation to eccentric exercise-induced skeletal muscle injury. In the exercise science field muscle soreness is most commonly measured using a visual analog scale (VAS) in which a subject reports their degree of soreness on a 10cm horizontal line. However, the measurement of muscle soreness using pressure algometry is common in clinical practice, and suggested to be a more precise measurement tool. PURPOSE: To determine the correlation between muscle soreness ratings using a 10cm VAS and pressure algometry readings in resistance trained men before and following 100 eccentric repetitions in the bench press exercise. METHODS: 21 resistance trained men (age: 24±6 years, height: 177±6 cm, weight: 88±21 kg, body fat: 12±9 %, 1-RMbench press: 102±16 kg, mean±SD) performed 10 sets of 10 eccentric repetitions in the bench press exercise at 70% of their 1 -RM using a Smith machine. Muscle soreness was assessed pre-exercise, immediately (0), 24 and 48 hours post-exercise using both a 10cm VAS (recorded following 2 repetitions of the barbell bench press using a standard 20kg bar) and pressure algometry via a force dial (Wagner Instruments; Greenwich, CT) at selected anatomical sites (pectoralis major, anterior deltoid, triceps lateral head, triceps long head). For each site, both the onset of pain and the tolerance of pain were recorded. Pairwise correlations for all measurements were made and an alpha level of < 0.05 was accepted as statistically significant. RESULTS: Subjects reported increased muscle soreness following exercise, as evidenced by a time main effect using the VAS data (pre: 0.95±0.22, 0 post: 4.06±0.45, 24 post: 6.40±0.40, 48 post: 5.83±0.53, mean±SEM, p <0.0001). Statistically significant correlations were noted between the VAS data and the pressure algometry measures for the chest onset of pain (r = −0.287, p = 0.008) and tolerance (r = −0.254, p = 0.0196), the deltoid tolerance (r = −0.255, p = 0.019), and the triceps long head tolerance (r = −0.228, p = 0.037). CONCLUSIONS: These data indicate that in resistance trained men, pressure algometry measures of muscle soreness are correlated to VAS measures in a site specific manner. However, while statistical significance was noted between the VAS data and these selected sites, the correlations are weak. Furthermore, although all muscles measured are recruited during the bench press exercise, the degree of soreness is not uniform across muscle groups, possibly due to differences in muscle recruitment.

Mapping between Visual Analogue Scale and Standard Gamble data; results from the UK Health Utilities Index 2 valuation survey

We examine the relationship between Visual Analogue Scale (VAS) and Standard Gamble (SG) assumed in the development of the multiplicative multi-attribute utility functions (M-MAUFs) for the Health Utilities Index (HUI) Mark 2 and Mark 3, using data from a UK valuation study of the HUI2. A range of functional forms are considered, and are compared on the basis of their explanatory power and predictive ability.A restricted cubic function fits the data better than a power curve with a mean absolute error (MAE) of 0.025 and root mean square error (RMSE) of 0.029 compared to a MAE of 0.135 and RMSE of 0.135 for the power curve. The use of a cubic mapping function instead of a power function leads to different predicted health state values. We question the reliance on the assumption of a power curve relationship between VAS and SG data, in the Health Utilities Index valuation framework. Our results demonstrate that further work is required to examine the appropriateness of the published M-MAUFs for the Health Utilities Indices.

Valuation Structures of Health States Revealed with Singular Value Decomposition

A basic mathematical routine called singular value decomposition (SVD) is introduced and applied to explore the applicability of this methodology in the context of health state valuations. SVD dissects a data matrix into 3 separatematrices that contain all the information present in the original data. Eachmatrix comprises a specific type of information. One matrix comprises arrays of weights that show the different valuation structures (i.e., similar ways among respondents to quantify specific sets of health states). A 2nd matrix with weights expresses how strongly each respondent's ratings are related to each of the valuation structures, and a 3rd matrix contains the percentages of variance associated with the valuation structures. SVD was applied to data from a group of 340 respondents who each gave a value to 16 health states using the time tradeoff (TTO) method and the visual analog scale (VAS). SVD of the VAS data showed 1 distinct response pattern that accounted for 91.6% of the total variance. The contribution of the 1st component in the TTO data wasmuch lower (57.4%), and a 2nd component (15.6%) could be identified that reflected a distinct preference structure opposed to the 1st and principal component. Application of SVD to the TTO data revealed that respondents fell into 2 different groups in their TTO evaluations, but respondents weremore similar to each other in their VAS responses. The author discusses other applications of SVD to clinical research.

Utility Scores for the Health Utilities Index Mark 2

The Health Utilities Index is one of the most widely used generic health status classification systems. The valuation algorithm rests upon a power transformation between visual analog scale (VAS) and standard gamble (SG) data. This transformation has been the subject of much debate. To date, the literature has concentrated upon the mapping functions themselves. We examine whether alternative mapping functions produce more accurate utility predictions. We undertook valuation interviews with 201 members of the UK general population, following the methods of the original Health Utilities Index-2 valuation survey. We estimated a cubic and a power mapping function using the mean VAS and SG data from the survey and calculated 2 alternative Multiplicative Multi Attribute Utility Functions (MAUFs). Using a validation sample, we assessed the predictive precision of the models in terms of accuracy (root mean square error and mean absolute error); clinical importance of the prediction error (% states with prediction error greater than 0.03); bias (t test); and whether the prediction error was related to the health state severity (Ljung Box Q statistic). The power MAUF was an extremely poor predictive model, mean absolute error = 0.18, root mean square error = 0.206. The predictions were biased (t = -12.92). The errors were not related to the severity of the health state, (Liung Box = 10.87). The Cubic MAUF was a better predictive model than the Power MAUF (mean absolute error = 0.084, root mean square error = 0.101). The Cubic MAUF also produced biased predictions (t = -3.57). The prediction errors were not related to the severity of the health state (Liung Box = 5.242). The Power MAUF is considerably worse than the Cubic MAUF. Our results suggest that the problems with the power function can translate into significant problems with predictive performance of the MAUF.

COMPARATIVE STUDY OF EFFICIENCY OF DESTANDAU ENDOSCOPIC DISCECTOMY AND OPEN MICROSURGICAL DISCECTOMY FOR LUMBAR DISC HERNIATION

Objectives. To estimate efficiency, safety and traumatizing impact of endoscopic discectomy in comparison with traditional microsurgical discectomy. Material and methods. A total of 330 patients underwent Destandau endoscopic discectomy and 964 – open microsurgical discectomy. The operative times, terms of patient postoperative bed and hospital stays, postoperative dynamics of neurologic deficiency, surgical complications and frequency of herniation recurrences were estimated in both groups. Pain intensity was assessed with the 10-score Visual Analog Scale (VAS), and functional activity – with the Oswestry Disability Index (ODI). Results of surgical treatment were estimated in 8–10 days, 6 and 12 months after operation. Results. VAS and ODI data have not revealed essential distinctions in pain regression dynamics after endoscopic and open surgeries. Surgical complications after endoscopic intervention were not more often, than after microsurgical discectomy. Damage of dura mater occurred in 2.4 % of cases, and increase in neurologic deficiency (hypoesthesia) – in 0.6 %. Herniation recurrences have evolved in 3.0 % of cases after endoscopic discectomy and in 4.7 % – after open microsurgical one. Conclusion. Destandau endoscopic surgery is a low invasive method of effective treatment for lumbar disc herniations, which by its technical opportunities and results is competitive with classical open microsurgical discectomy.

Integrating preferences into health status assessment for amyotrophic lateral sclerosis: The ALS Utility Index

We developed a preference-based measure, the Amyotrophic Lateral Sclerosis Utility Index (ALSUI), allowing computation of US population-based utility weights for the wide range of health states observed among ALS patients. A multi-attribute utility approach was used. An ALS Health State Classification System was developed comprising the following attributes with different severity levels: Speech and Swallowing (A1); Eating, Dressing, and Bathing (A2); Leg Function (A3); and Respiratory Function (A4). An internet-based survey was administered to a random sample of the US population to assess preferences for ALS health states based on this system using visual analog scale (VAS) and standard gamble (SG) questions. Using the VAS and SG data from 1374 individuals in the general population, utility functions were computed that corresponded to each severity level within A1, A2, A3, and A4. ALSUI scores for a given patient are computed by inputting his corresponding utility functions into the following multiplicative formula: ALSUI score = 1.06 x (A1 x A2 x A3 x A4) - 0.06 on a scale where 0.0 reflects death and 1.0 reflects healthy. This study provides a useful tool for classifying ALS patients and determining a general public-based utility score for ALS health states.

Effect of conventional TENS on pain and electromyographic activity of masticatory muscles in TMD patients

Temporomandibular disorders (TMD) are characterized by several signs and symptoms, such as pain and changes in the electrical activity of masticatory muscles. Considering that transcutaneous electrical nerve stimulation (TENS) is a resource indicated to promote analgesia, the objective of this study was to evaluate the effect of TENS on pain and electromyographic (EMG) activity of the jaw elevator muscles in TMD patients. This study evaluated 35 female volunteers: 19 TMD patients (mean age = 23.04 +/- 3.5) and 16 normal subjects (mean age = 23.3 +/- 3.0). Transcutaneous electrical nerve stimulation (conventional mode, 150 Hz) was applied once to each group for 45 minutes. Surface electromyography (gain of 100 times and 1 kHz sampling frequency) and the visual analogue scale (VAS) were applied before and immediately after TENS application. Both VAS data and root mean square (RMS) values were analyzed using Student's t-test. The TMD group, compared to the control group, showed higher EMG activity of the jaw elevator muscles at rest. No difference was observed between the groups regarding maximum voluntary clenching (MVC). In TMD patients, TENS reduced both pain and EMG activity of the anterior portion of the temporal muscle, increasing the activity of the masseter muscles during MVC. It is possible to conclude that a single TENS application is effective in pain reduction. However, it does not act homogeneously on the features of the electric activity of the muscles evaluated.

Effect of tens on the activation pattern of the masticatory muscles in TMD patients

Temporomandibular disorder (TMD) is characterized by several signs and symptoms, such as pain and changes in the activation pattern of the masticatory muscles. Thus, the objective of this study was to evaluate the effect of transcutaneous electrical nerve stimulation (TENS) of the electromyographic pattern of the masticatory muscles in individuals with myogenic TMD. This study evaluated 40 female volunteers: 20 with myogenic TMD (x=23.04 ± 3.5) and 20 normal individuals (x=23.3 ± 3). TENS (conventional mode, 150Hz) was applied once to each group for 45 minutes. The electromyographic (EMG) signal (gain of 100 times and 1KHz sampling frequency) and visual analogue scale (VAS) were applied before and immediately after TENS application. The VAS data were analyzed using paired t-test. The EMG signals were analyzed using the normalized linear envelopes. The results showed that individuals with TMD have an alteration in the activation pattern of the masticatory muscles, when compared to the control group, and the TENS reversed this pattern. TENS reduced the pain intensity in the TDM group. We conclude that a single TENS application is effective in pain reduction and promotes betterments in the activation pattern of the masticatory muscles in individuals with TMD.

Utilities derived from visual analog scale scores in patients with HIV/AIDS.

Visual analog scale (VAS) scores are used as global quality-of-life indicators and, unlike true utilities (which assess the desirability of health states v. an external metric), are often collected in HIV-related clinical trials. The purpose of this study was to derive and evaluate transformations relating aggregate VAS scores to utilities for current health in patients with HIV/AIDS. HIV-specific transformations were developed using linear and nonlinear regression to attain models that best fit mean VAS and standard gamble (SG) utility values directly derived from 299 patients with HIV/AIDS participating in a multicenter study of health values. The authors evaluated the transformations using VAS and SG utility values derived directly from patients in other HIV/AIDS studies. Derived transformations were also compared with published transformations. A simple linear transformation was derived (u = 0.44v + 0.49), as was the exponent for a curvilinear model (u = 1 - [1 - v]1.6), where u = the sample mean utility and v the sample mean VAS score. The curvilinear transformation predicted values within 0.10 of the actual SG utility in 5 of 8 estimates and within 0.05 in 3 of 8 estimates (absolute error ranged from -0.01 to +0.21). The linear transformation performed somewhat better, predicting within 0.10 of the actual SG value in 6 of 8 cases and within 0.05 in 5 of 8 estimates (absolute error ranged from -0.05 to +0.13). An alternative linear model (u = v + 0.018) derived from the literature performed similarly to our linear model (7 of 8 predictions within 0.10, 1 of 8 estimates within 0.05, and absolute error ranging from -0.15 to +0.10), whereas an alternative published curvilinear model (u = 1 - [1 - v]2.3) performed the least well (2 of 8 estimates within 0.10 of the actual values and no estimates within 0.05). Predicted utilities are a reasonable alternative for use in HIV/AIDS decision analyses and cost-effectiveness analyses. Linear transformations performed better than curvilinear transformations in this context and can be used to convert aggregate VAS scores to aggregate SG values in large HIV/AIDS studies that collect VAS data but not utilities.

Validation of a Verbally Administered Numerical Rating Scale of Acute Pain for Use in the Emergency Department

Verbally administered numerical rating scales (NRSs) from 0 to 10 are often used to measure pain, but they have not been validated in the emergency department (ED) setting. The authors wished to assess the comparability of the NRS and visual analog scale (VAS) as measures of acute pain, and to identify the minimum clinically significant difference in pain that could be detected on the NRS. This was a prospective cohort study of a convenience sample of adults presenting with acute pain to an urban ED. Patients verbally rated pain intensity as an integer from 0 to 10 (0 = no pain, 10 = worst possible pain), and marked a 10-cm horizontal VAS bounded by these descriptors. VAS and NRS data were obtained at presentation, 30 minutes later, and 60 minutes later. At 30 and 60 minutes, patients were asked whether their pain was "much less," "a little less," "about the same," "a little more," or "much more." Differences between consecutive pairs of measurements on the VAS and NRS obtained at 30-minute intervals were calculated for each of the five categories of pain descriptor. The association between VAS and NRS scores was expressed as a correlation coefficient. The VAS scores were regressed on the NRS scores in order to assess the equivalence of the measures. The mean changes associated with descriptors "a little less" or "a little more" were combined to define the minimum clinically significant difference in pain measured on the VAS and NRS. Of 108 patients entered, 103 provided data at 30 minutes and 86 at 60 minutes. NRS scores were strongly correlated to VAS scores at all time periods (r = 0.94, 95% CI = 0.93 to 0.95). The slope of the regression line was 1.01 (95% CI = 0.97 to 1.06) and the y-intercept was -0.34 (95% CI = -0.67 to -0.01). The minimum clinically significant difference in pain was 1.3 (95% CI = 1.0 to 1.5) on the NRS and 1.4 (95% CI = 1.1 to 1.7) on the VAS. The findings suggest that the verbally administered NRS can be substituted for the VAS in acute pain measurement.