Is your osteoarthritic knee or back acting up lately?
Well, you may not be able to blame this month’s cold temperatures or other weather-related factors — at least, according to two recent Australian studies.
And that may be true of many other aches and pains as well, say the studies’ authors.
“The belief that pain and inclement weather are linked dates back to Roman times,” said Chris Maher, director of the musculoskeletal division of the George Institute for Global Health, which conducted the studies, in a released statement. “But our research suggests this belief may be based on the fact that people recall events that confirm their pre-existing views.”
“Human beings are very susceptible so it’s easy to see why we might only take note of pain on the days when it’s cold and rainy outside, but discount the days when they have symptoms but the weather is mild and sunny.”
A common condition
Osteoarthritis is the most common form of arthritis, affecting about 27 million adults here in the United States. It’s caused by a breakdown of the protective cartilage at the end of the bones in a joint. Age is the biggest risk factor for the condition, along with gender (women are more prone to osteoarthritis for reasons that aren’t entirely clear), obesity, a previous joint injury and repetitive stress to the joint.
Osteoarthritis can occur in any joint in the body, but it most typically affects weight-bearing ones, such as those of the spine and knees. In the United States, an estimated 13 percent of women and 10 percent of men aged 60 or older have knee arthritis that causes symptoms, such as pain, swelling, stiffness and lack of flexibility. Each year, doctors perform 660,000 total knee replacement surgeries in the United States, a number that is expected to grow to 2 million annually by 2030 as the country’s population ages.
It’s also estimated that four in five American adults develop back pain during their lifetime, typically after the age of 40. But how many of those cases are due specifically to osteoarthritis is, as one expert put it, “The $64,000 question.”
For the first study, which was published in the journal Pain Medicine, Maher and his colleagues used four years of data collected from 981 patients in Sydney who had gone to their doctors to report an episode of lower back pain, but who had also said they had been pain-free for at least a month before the symptoms had started. The researchers then used data from the Australian Bureau of Meteorology to compare the weather conditions for the week in which each patient had first noticed the pain with the conditions one week and one month before (as a control measure).
They found no link between back pain and several weather parameters, including temperature, humidity, air pressure, wind direction or precipitation. Higher temperatures were associated with a slight increase in the likelihood of the onset of a bout of back pain, but that amount of increase was not considered statistically significant.
In the second study, published in the journal Osteoarthritis and Cartilage, the researchers recruited 345 people with diagnosed knee osteoarthritis. Participants were asked at the start of the study to rate their knee pain on a scale of 1 to 10. They were then asked to log in to a dedicated website every 10 days over the next three months to repeat the rating of their perception of their pain. They were also asked to do a similar report whenever they experienced a particularly disabling bout of symptoms that lasted for more than eight hours. The researchers considered any rating that jumped two points or higher on the scale to be an exacerbation of the pain.
Once again, the researchers compared those pain flare-ups with weather conditions at the time and found no association in regards to variation in temperature, air humidity and barometric pressure. There was a slight increase in the risk of a pain flare-up when temperatures exceeded 86 degrees Farenheit, but, as with the back-pain study, that association was not statistically significant.
Limitations and implications
These studies have limitations, of course. They relied on the patients accurately reporting when their pain began, and, in the case of the knee study, also relied on the patients taking the time to regularly log in and fill out an online pain survey. Also, in that study only 171 people experienced a flare-up of knee pain, a low number that might have skewed the results.
Still, these two studies support earlier research reported in 2014 by the same group of researchers, which also found no link between low back pain and weather conditions. Other studies, however, have produced conflicting results, so the final word on this issue is not yet settled.
The authors of the current studies stand by their findings, however, and believe they offer important and helpful information to the millions of people who live with arthritis.
“People who suffer from either of these conditions should not focus on the weather as it does not have an important influence on your symptoms and it is outside your control,” said Manuela Ferreira, a senior research fellow at the George Institute for Global Health and one of the co-authors of the study, in the released statement.
“What’s more important is to focus on things you can control in regards to managing pain and prevention,” she added.