Lack of interchangeability between visual analogue and verbal rating pain scales: a cross sectional description of pain etiology groups

BACKGROUND: Rating scales like the visual analogue scale, VAS, and the verbal rating scale, VRS, are often used for pain assessments both in clinical work and in research, despite the lack of a gold standard. Interchangeability of recorded pain intensity captured in the two scales has been discussed earlier, but not in conjunction with taking the influence of pain etiology into consideration. METHODS: In this cross-sectional study, patients with their pain classified according to its etiology (chronic/idiopathic, nociceptive and neuropathic pain) were consecutively recruited for self-assessment of their actual pain intensity using a continuous VAS, 0–100, and a discrete five-category VRS. The data were analyzed with a non-parametric statistical method, suitable for comparison of scales with different numbers of response alternatives. RESULTS: An overlapping of the VAS records relative the VRS categories was seen in all pain groups. Cut-off positions for the VAS records related to the VRS categories were found lower in patients with nociceptive pain relative patients suffering from chronic/idiopathic and neuropathic pain. When comparing the VAS records transformed into an equidistant five-category scale with the VRS records, systematic disagreements between the scales was shown in all groups. Furthermore, in the test-retest a low percentage of the patients agreed to the same pain level on the VAS while the opposite hold for the VRS. CONCLUSION: The pain intensity assessments on VAS and VRS are in this study, not interchangeable due to overlap of pain records between the two scales, systematic disagreements when comparing the two scales and a low percentage intra-scale agreement. Furthermore, the lower VAS cut-off positions relative the VRS labels indicate different meaning of the rated pain intensity depending on pain etiology. It is also indicated that the scales have non-linear properties and that the two scales probably have different interpretation. Our findings are in favor of using the VRS in pain intensity assessments but if still the VAS is preferred, the VAS data should be analyzed as continuous using statistical methods suitable for ordinal data. Furthermore, our findings indicate a risk to over or under estimate the patient's perceived pain when interpreting condensed VAS data

Pain following spinal cord injury

The aims of this thesis were to assess and characterise nociceptive and neuropathic pain, the use of pharmacological and non-pharmacological pain treatment, and the influence of pain on the quality of sleep in a population following spinal cord injury (SCI). This thesis is divided into five separate studies: I. Pain in a Swedish spinal cord injury population. II. Gender related differences in pain in spinal cord injured individuals. III. Use of analgesic drugs in individuals with spinal cord injury. IV. Non-pharmacological pain-relieving therapies in individuals with spinal cord injury: a patient perspective. V. Quality of sleep in individuals with spinal cord injury; a comparison between patients with and without pain. Paper I encompassed 456 individuals with an SCI, which was 76.5% of the total prevalence population in the greater Stockholm area. In paper II, 65 women were matched with 65 men regarding age, ASIA impairment grade, and level of lesion. These patients were followed up 3 years later regarding the use of analgesic drugs (III) and non-pharmacological treatment (IV). They were also assessed regarding quality of sleep together with a sample of 107 patients with SCI (V). Of 456 patients with an SCI (I), 291 (63.7%) suffered from pain: of these, 46% had pain classified as neurogenic and 26% as both nociceptive and neurogenic. Onset of pain was most often within 3 months and localised to areas below the level of the lesion. The median rating of the general pain intensity was 46/100 on a visual analogue scale. Pain was most common in patients with motor and sensory incomplete lesions, ASIA impairment grade D, and there was a correlation between pain and higher mean age at injury and between pain and female gender. In paper II we found that although men and women described their pain similarly, more women were classified as sufferers from nociceptive pain. The use of analgesics was higher amongst women, especially the use of opiates and non-steroidal anti-inflammatory drugs. At the 3-year follow-up, the remaining 123 patients had increased the number of drugs they used for pain relief, but the ratings of pain intensity were similar to those 3 years before. Predictive for the use of analgesics were high ratings of the affective component of pain, low ratings of leisure time activities, and the presence of stabbing/cutting pain. Regarding the use of non-pharmacological treatment (IV), 63.3% had tried one or more treatments for pain relief. Acupuncture, massage therapy, and transcutaneous electrical nerve stimulation were the most commonly tried therapies. Patients considered massage and treatment with heat to give best pain alleviation. Predictive for the use of non-pharmacological treatment were high ratings of general pain intensity, aching pain, and cutting/stabbing pain. In the last study (V) we assessed quality of sleep in patients without pain, with intermittent pain, and with continuous pain. We found that the latter reported a poorer quality of sleep than did patients with intermittent pain or no pain. Predictive for poor sleep quality were anxiety, ratings of the worst pain intensity, and depression. This thesis concludes that pain after spinal cord injury is common - often debilitating - and that relief of pain is difficult to obtain with the pharmacological and non-pharmacological treatment options available today. Pain also interferes negatively with the quality of sleep. Patients with SCI and pain suffer from a common complication and need a multidisciplinary team for assessment and treatment to decrease not only the intensity of the pain but also the suffering and the consequences of pain

Pain After Spinal Cord Injury: An Evidence-based Review for Clinical Practice and Research: Report of the National Institute on Disability and Rehabilitation Research Spinal Cord Injury Measures Meeting

Background/Objectives: To examine the reliability, validity, sensitivity, and practicality of various outcome measures for pain after spinal cord injury (SCI), and to provide recommendations for specific measures for use in clinical trials. Data Sources: Relevant articles were obtained through a search of MEDLINE, EMBASE, CINAHL, and PubMed databases from inception through 2006. Study Selection: The authors performed literature searches to find articles containing data relevant to the reliability and validity of each pain outcome measure in SCI and selected non-SCI populations. Data Extraction: After reviewing the articles, an investigator extracted information utilizing a standard template. A second investigator reviewed the chosen articles and the extracted pertinent information to confirm the findings of the first investigator. Data Synthesis: Taking into consideration both the quantity and quality of the studies analyzed, judgments on reliability and validity of the measures were made by the two investigators. Based upon these judgments, recommendations were formulated for use of specific measures in future clinical trials. In addition, for a subset of measures a voting process by a larger group of SCI experts allowed formulation of recommendations including determining which measures should be incorporated into a minimal dataset of measures for clinical trials and which ones need revision and further validity and reliability testing before use. Conclusions: A 0-10 Point Numerical Rating Scale (NRS) is recommended as the outcome measure for pain intensity after SCI, while the 7-Point Guy/Farrar Patient Global Impression of Change (PGIC) scale is recommended as the outcome measure for global improvement in pain. The SF-36 single pain interference question and the Multidimensional Pain Inventory (MPI) or Brief Pain Inventory (BPI) pain interference items are recommended as the outcome measures for pain interference after SCI. Brush or cotton wool and at least one high-threshold von Frey filament are recommended to test mechanical allodynia/hyperalgesia while a Peltier-type thermotester is recommended to test thermal allodynia/hyperalgesia. The International Association for the Study of Pain (IASP) or Bryce-Ragnarsson pain taxonomies are recommended for classification of pain after SCI, while the Neuropathic Pain Scale (NPS) is recommended for measuring change in neuropathic pain and the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) for quantitating neuropathic and nociceptive pain discrimination