Comparison of a verbal numeric rating scale with the visual analogue scale for the measurement of acute pain. [Article

Department of Emergency Medicine, St George Hospital, Gray St, Kogarah, NSW 2217, Australia.
Emergency Medicine Australasia 10/2003; 15(5-6):441-6. DOI: 10.1046/j.1442-2026.2003.00499.x
Source: PubMed


To test the agreement between the visual analogue scale (VAS) and a verbal numeric rating scale (VNRS) in measuring acute pain, and measure the minimum clinically significant change in VNRS.
Patients scored their pain by the VAS and the VNRS, then re-scored their pain every 30 min for up to 2 h. Patients also recorded whether their pain had improved or worsened. Agreement between scores was evaluated, and where patients scored their pain as 'a bit worse' or 'a bit better' the mean change in VNRS was calculated.
A total of 309 paired observations were obtained from 79 patients. The VAS and VNRS were highly correlated (r = 0.95, 95% CI 0.94-0.96). The VNRS was significantly higher than the VAS for the paired observations, with 95% of the differences between VAS and VNRS lying between -2.3 and 1.3 cm. The minimum clinically significant difference in VNRS was 1.4 cm (95% CI 1.2-1.6).
The VNRS performs as well as the VAS in assessing changes in pain. However, although the VAS and VNRS are well correlated, patients systematically score their pain higher on the VNRS, with an unacceptably wide distribution of the differences.

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    • "One of the medications which its anxiolytic effects have been studied in dental procedures and on patients with cancer is nitrous oxide (N2O) (3-5). Administration of 50% N2O causes analgesia and reduces fear of pain and anxiety in patients, but has mild and self-limited side effects (6-8). Considering the adverse effects of anxiety on patients and also the side effects of usual anxiolytic medications, efforts to achieve an effective modality to treat anxiety in pregnant women who undergo caesarean section are important. "
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    ABSTRACT: Background:Anxiety is an unpleasant experience that may have adverse effects on the process of anesthesia, cesarean delivery, recovery period and postoperative pain. Anxiety can also affect maternal satisfaction of the medical cares that provided by the medical team.Objectives:To compare the effects of inhalational 50% nitrous oxide (N2O) with oxygen on reducing anxiety and pain in parturients who have undergone caesarean section under spinal anesthesia.Patients and Methods:In this double-blind clinical trial, 56 primigravid parturients were randomly assigned into two groups according to the operating list schedule. The experimental group received inhalational 50% N2O three minutes before spinal anesthesia to the end of delivery. The control group received only oxygen. Flow meters were covered by a dark shield and monitored by an experienced nurse anesthetist. Pain and anxiety of patients were measured using visual analogue scale (VAS) by another nurse who was neither involved in the anesthetic process nor aware of the participants' allocation and inhalation agents. Data regarding sedation level, ephedrine use, nausea, vomiting, and neonate Apgar score were recorded as well.Results:Overall mean ± SD of anxiety VAS scores was 1.77 ± 1.5 in the experimental group and 3.12 ± 1.73 in the control groups (P = 0.003). The mean ± SD of pain VAS scores of the experimental and control groups were 0.82 ± 1.5 and 1.64 ± 1.45, respectively (P = 0.042). No significant differences were seen regarding blood oxygen saturation, neonate Apgar scores, total used ephedrine, operation time, delivery time, nausea, and vomiting between the two studied groups.Conclusions:Inhalation of 50% N2O can significantly decrease anxiety (without clinically significant side effects) compared with O2 inhalation in parturients who have undergone caesarean section under spinal anesthesia.
    Full-text · Article · May 2014 · Anesthesiology and Pain Medicine
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    • "As this was a non-inferiority study, the sample size was determined based on how much higher the pain score in the intervention group would have to be to show that VL + LA should not be used without analgesics (equivalence margin). Studies using the NRS in combination with physiological measures of pain have shown that the minimum clinically relevant difference in pain is around 1.3 [18,19]. The standard deviation (SD) of pain scores during gynecological procedures tends to fall within the range of 3–3.5 using an 11-point scale [20,21]. "
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    ABSTRACT: Background: Vocal local (VL) is a non-pharmacological pain management technique for gynecological procedures. In Africa, it is usually used in combination with pharmacological analgesics. However, analgesics are associated with side-effects, and can be costly and subject to frequent stock-outs, particularly in remote rural settings. We compared the effectiveness of VL + local anesthesia + analgesics (the standard approach), versus VL + local anesthesia without analgesics, on pain and satisfaction levels for women undergoing tubal ligations in rural Kenya. Methods: We conducted a site-randomised non-inferiority trial of 884 women receiving TLs from 40 Marie Stopes mobile outreach sites in Kisii and Machakos Districts. Twenty sites provided VL + local anesthesia + analgesics (control), while 20 offered VL + local anesthesia without additional analgesics (intervention). Pain was measured using a validated 11-point Numeric Rating Scale; satisfaction was measured using 11-point scales. Results: A total of 461 women underwent tubal ligations with VL + local anesthesia, while 423 received tubal ligations with VL + local anesthesia + analgesics. The majority were aged >= 30 years (78%), and had > 3 children (99%). In a multivariate analysis, pain during the procedure was not significantly different between the two groups. The pain score after the procedure was significantly lower in the intervention group versus the control group (by 0.40 points; p = 0.041). Satisfaction scores were equally high in both groups; 96% would recommend the procedure to a friend. Conclusion: VL + local anesthesia is as effective as VL + local anesthesia + analgesics for pain management during tubal ligation in rural Kenya. Avoiding analgesics is associated with numerous benefits including cost savings and fewer issues related to the maintenance, procurement and monitoring of restricted opioid drugs, particularly in remote low-resource settings where these systems are weak.
    Full-text · Article · Feb 2014 · BMC Women's Health
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    • "A 1 cm difference on a 10 cm VAS represents 10% of the scale, and to detect mean differences of this magnitude between the two arms of the trial with 90% power (at the 5% significance level) will require sample sizes of 203, 144 and 86 per group respectively in the 3 scenarios. A 1 cm difference is similar to the difference in pain intensity at 60 minutes found by Fairlie (0.9), is not larger than the 1.4 cm identified by Holdgate et al [13] as being the minimum change in pain that can be subjectively identified by patients with acute pain, and represents a standardised effect size of 0.38. We will set sample size at the higher figure of 203 per group. "
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    Full-text · Article · Jul 2011 · BMC Pregnancy and Childbirth
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