Led by Peter Croft of Keele University in Keele, UK, the authors surveyed a total of 5,364 patients aged 50 years or older who were registered with 3 general practices in North Staffordshire, UK. Each participant completed a questionnaire that included a body manikin on which they shaded any areas where they had experienced pain for one or more days during the last month. Pain was categorized into regions, which included: knee, neck, hand, lower back, hip, and foot and ankle. Based on where the pain occurred, participants were then grouped into (i) those with no pain at all, (ii) those with knee pain, either alone or with pain in 1 or 2 or more locations elsewhere, (iii) those with no knee pain but with pain in 1, 2 or 3 or more locations other than the knee.
A standard health survey used to determine the influence of pain elsewhere on general health was also completed, as well as an index to measure pain and disability specifically related to the knee. Obesity, anxiety and depression, all of which are linked to widespread pain, were also measured using various scales.
Of those surveyed, slightly more than one-third (1,909) ended up in the no pain group, 41% (2,210) in the knee pain group, and 23% (1,245) in the pain elsewhere group. Decreased physical function increased with the number of pains in the body, both in the knee and elsewhere. In those with at least 3 pain regions, the subgroup that included knee pain had worse physical function. This group was also more likely to be depressed than either those with no pain at all or those who had pain in a location other than the knee, even if it was in 3 or more regions.
The results indicate that knee pain does not tend to occur by itself, and that when it occurs with pain in other regions, it is associated with poorer general and psychological health. In addition, the results suggest a link between the extent of pain in the body and the impact of pain in a particular region. "We have shown that knee-specific pain and disability are actually worse in the presence of pains elsewhere than the knee, even after accounting for poorer psychological health," the authors state.
"The practical importance of our findings is that the presence and extent of pain in other sites may be an important determinant of outcome in patients who present with knee pain, just as it appears to be in those who present with back pain [as shown in previous studies]," the authors conclude. In addition, they note that managing pain in one region such as the knee (with local treatments such as physiotherapy or total knee replacement) might have beneficial effects on the general perception of pain and on the frequency and impact of pains elsewhere in the body.
Article: "'Pain Elsewhere' and the Impact of Knee Pain in Older People," Peter Croft, Kelvin Jordan, and Clare Jinks, Arthritis & Rheumatism, August 2005; 52:8; pp. 2350-2354. Article is available via Wiley InterScience at http://www.interscience.wiley.com/journal/arthritis.
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