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Q: Where are older adults more likely to have painful arthritis, Oregon or Saudi Arabia?

A: The prevalence in chilly, wet Oregon in adults ages 65 to 74 is 49%, . The prevalence in hot, dry Saudi Arabia is 61% for that age group, .

Do your arthritis patients complain that their symptoms are influenced by the cold and wet weather, or even that they can predict a coming storm by their joint pain? There's plenty of support for this -- the Weather Channel has a daily updated

And there's plenty of historical precedent. Almost 2,500 years ago, Hippocrates described the effects of wind and rain on chronic disease in Air, Water, and Places. Reports in the late 19th and early 20th centuries suggested links between atmospheric events, such as barometric pressure changes or aurora borealis with pain, and often recommended that afflicted individuals move to sunny climes.

Then in the late 1990s, suggesting that people tend to see correlations among unrelated events, which the authors termed "selective matching, the tendency to focus on salient coincidences, thereby capitalizing on chance and neglecting contrary evidence." The researchers, from Toronto and Stanford, Calif., concluded that "people's beliefs about arthritis pain and the weather may tell more about the workings of the mind than of the body."

Now, a group of researchers led by Erik J. Timmermans, PhD, from VU University Medical Center in Amsterdam, have sought to quantify this link and examine contributing factors, conducting with different climates.

The 712 survey participants were residents of Germany, Italy, U.K., and the Netherlands, which are considered to have relatively warm and wet climates. Spain, which has a relatively warm and dry climate, and Sweden, which is characterized by a relatively cold and wet climate, were also included.

Patients' mean age was 73 years, 72% were women, and 67% considered themselves to be "weather sensitive."

When the researchers compared the weather-sensitive patients with those who didn't consider themselves sensitive, they found that women, the less educated, and more anxious and depressed patients were more often sensitive.

Weather-sensitive individuals also had less of a sense of mastery over their lives.

Among the 469 individuals who considered themselves weather sensitive, almost 40% said damp and rainy conditions worsened their symptoms, 30% said only cold bothered them, and 5% said hot weather was worse for their pain. Small numbers reported increased pain with both hot and cold weather, or to rain and cold and heat.

Interestingly, the percentage of patients who were weather sensitive was highest in warm, dry climates like Spain and Italy (77%) and lowest in the cold, wet climate of Sweden (57%). In addition, residents of warm, dry climates reported more intense joint pain than those in cold, wet climates.

Possible explanations suggested by Timmermans' group included the mechanistic:

"Changes in temperature and humidity may influence the expansion and contraction of different tissues in the affected joint, which may elicit a pain response. In addition, low temperatures may increase the viscosity of synovial fluid, thereby making joints stiffer and perhaps more sensitive to the pain of mechanical stresses."

And the ecological:

"The climates in both Mediterranean countries are warmer compared to the climate in Sweden. As a result, older people with osteoarthritis in Italy and Spain may be more often outside compared to those in Sweden .... As a consequence, they may be more aware of the effect of weather on their pain and are more likely to report weather sensitivity."

And the psychological:

"The disease course of osteoarthritis is often characterized by the alternation of stable periods of varying length, characterized by a low level or absence of symptoms with periods of flare-up or exacerbation. The uncertainty about the recurrence of pain may lead to anxiety in people with osteoarthritis and this might encourage the desire to have an explanation for the worsening of their pain."

In any case, "the common belief that joint pain in osteoarthritis becomes worse by living in a cold and damp climate is not supported by our results," they stated.

They concluded that clinicians' appreciation of older patients' potential weather sensitivity -- wherever they live -- may be key. "Early treatment of weather-sensitive individuals with osteoarthritis using cognitive and psychological interventions may reduce suffering and may help them to maintain a functionally effective lifestyle," they concluded.

Rheuminations is a blog by Nancy Walsh for readers with an interest in rheumatology.

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