Vol. 19 Issue 9
The Rheumatoid Arthritis Pain Scale (RAPS)
Imagine a 43-year-old wife and mother who presents with gnarled and misshapen hands and feet, partially fused wrists, swollen joints and calluses under the pads of her feet.
Imagine ruptured tendons, fallen arches, severe ankle pronation. Imagine the misery of a 3-year-old in pain and stiff as a result of inflamed, swollen joints.
As health care providers, these scenarios are not too difficult to imagine. They are often a reality for many of the patients that we see suffering from the debilitating effects of rheumatoid arthritis (RA).
RA is an auto-immune disorder of unknown cause that primarily affects the peripheral joints. RA causes the joint lining to swell and produce a chemical substance that attacks and destroys the joint surface. Most commonly, the most affected joints are the MCP followed by the wrist, PIP, knee, MTP, shoulder, ankle, cervical spine, hip, elbow and temporomandibular.1
Though RA is less common than OA, it affects almost 3 million Americans. The worldwide incidence of RA is approximately three cases per 10,000 and the prevalence rate is approximately 1 percent.1 Symptoms common to this disease include fatigue, malaise, morning stiffness and pain.
Whereas joint involvement is the characteristic feature of patients with RA, where generally it is the small joints of the hands and feet that are affected in a relatively symmetrical manner, it is pain that is often a major limiting variable when it relates to function and mobility.
Pain is the major complaint in individuals with RA and a chief reason why medical attention is sought.2,3 It is this last variable that is often difficult to quantify from patient to patient.
To quantitatively assess pain in the patient with arthritis, numerous self-report methods have been employed. The most simple of these measurements is the 10cm visual analog scale (VAS) which is completed by the patient and scored quickly by a health professional. Other measures of pain include the McGill Pain Questionnaire4, the Health Assessment Questionnaire (HAQ),5 Modified Health Assessment Questionnaire (MHAQ),6 the Short Form 36 (SF-36),7 and the Western Ontario McMaster Questionnaire (WOMAC).8
While clinically valuable, these measures may be time-consuming to complete or may not be specific to RA as in the case of the WOMAC. To specifically address these concerns, the Rheumatoid Arthritis Pain Scale (RAPS) was developed to measure pain in adult patients with RA.9
The evaluation of pain is complex and involves a multidimensional approach in order to capture the many facets contained within this construct. The RAPS, based on the Gate control and the affective motivational theories of pain sets out to capture the multidimensionality of pain. The Gate control theory manifests that pain consists of sensory, motivational, affective and cognitive factors that are influenced by neural mechanisms in the dorsal horn of the spinal cord which act like a gate that regulates the flow of nerve impulses from the periphery to the central nervous system.9,10
The affective motivational model builds upon the Gate control theory. This theory consists of two stages. Stage 1 is termed the immediate affective stage that is comprised of immediate discomfort/unpleasantness and distress simultaneously occuring with the intensity of painful sensations and arousal. Stage 2 includes the memory and past experiences of pain and therefore is considered more cognitive in nature. Anderson (2001)9 proposed that if all the components of pain are present in RA, a comprehensive tool should exist to measure the various domains of pain.
The development of the RAPS as a clinical measure of pain in adults with RA was accomplished through clinical assessments and input from patients with RA as well as from theoretical concepts previously discussed.
Initial development of the instrument included 4 subscales each representing major pain dimensions in RA: physiologic, affective sensory-discriminative and cognitive. The scale initially consisted of 36 items, but after piloting with men and women 18 years and older diagnosed with RA, the items on the scale were reduced to 24.
The items are scored using a 7-point Likert scale ranging from "0 = never" to "6 = always," with a higher score considered to represent greater severity of pain.2.9 The complete RAPS is available in the appendix of the original article.9
Content, Concurrent Validity
Content validity of the RAPS was established by expert review. Six individuals actively involved in clinical work and research and publication in the field of rheumatology were recruited to review the subscales of the RAPS. Eleven items were removed as a result of the expert review with one item being removed because it caused confusion.
This led to there being 24 items on the final scale. Concurrent validity was established by comparing the domains of the RAPS with the total joint count (TJC) (Pearson correlation= 0.5237; p = 0.0001) and the modified VAS (Pearson correlation =.6756; p = 0.0001).
Construct validity was established via exploratory factor analysis which yielded three factors with criteria for factor loadings greater than 0.4 and 84 percent of the variance explained by these three factors. Factor loadings for the affective subscale were not larger than 0.3, which is considered standard for accepting a factor.
Total RAPS showed strong internal consistency (Cronbach's • = 0.91). Cronbach alpha for the four subscales ranged from 0.64 (affective subscale) to 0.86 (cognitive subscale). The sensory-discriminative subscale had a Cronbach's • = 0.80 and the physiologic subscale had a Cronbach's • = 0.70.
In its current form, the RAPS can be used to measure the relationship between pain and the effectiveness of treatment interventions for RA (medication, modalities, therapeutic exercise, etc.) in reducing pain in patients with RA.
The developer of the RAPS concludes that this understanding between pain associated with RA and interventions for the disease may help clinicians choose interventions that would be more effective in the treatment of this dimension of RA.
So for the 43-year-old female, for those burdened by ruptured tendons and the discomfort associated with fallen arches, and for children with juvenile RA who will become adults with RA, there is hope that an understanding of the multidimensionality of pain can lead to relief for at least this symptom of the disease.
1. Smith, H. (2008). Rheumatoid arthritis. Available at: http://www.emedicine.com/MED/topic2024.htm
2. Sokka, T. (2003). Assessment of pain in patients with rheumatic diseases. Best Practice Research in Clinical Rheumatology, 17(3), 427-449.
3. Anderson, K., Bradley, L., Turner, R., et al. (1994). Pain behavior of rheumatoid arthritis patients enrolled in experimental drug trials. Arthritis Care Research, 7, 64-68.
4. Melzack, R. (1975). The McGill Pain Questionnaire: Major properties and scoring methods. Pain, 277-299.
5. Fries, J., Spitz, P., Kraines, R., & Holman, H. (1980). Measurement of patient outcome in arthritis. Arthritis Rheumatology, 23, 137-145.
6. Pincus, T., Summey, J., Soraci, S., et al. (1983). Assessment of patient satisfaction in activities of daily living using a modified Stanford health assessment questionnaire. Arthritis Rheumatology, 26, 1346-1353.
7. Ware, J., & Sherbourne, C. (1992). The MOS 36-item short-form health survey (SF-36): I. Conceptual framework and item selection. Med Care, 30, 473-481.
8. Bellamy, N., Buchanan, W., Goldsmith, C., et al. (1998). Validation study of WOMAC: A health status instrument with osteoarthritis of the hip or knee. Journal of Rheumatology, 15, 1833-1840.
9. Anderson, D. (2001). Development of an instrument to measure pain in rheumatoid arthritis: Rheumatoid arthritis pain scale (RAPS). Arthritis Care Research, 45, 317-323.
10. Melzack, R., & Wall, P. (1965). Pain mechanisms: A new theory. Science, 50, 971-979.
Dr. Lewis is a private practice and consulting clinical specialist for ProfessionalSportsCare and Rehab. She lectures exclusively for GREAT Seminars and Books, Inc. Dr. Lewis is also the author of numerous textbooks. Her Website address is www.greatseminarsandbooks.com. Dr. Shaw is an assistant professor in the physical therapy program at the University of South Florida dedicated to the area of geriatric rehabilitation. She lectures exclusively for GREAT Seminars and Books in the area of geriatric function.