MONDAY, Oct. 18 (HealthDayNews) -- For years, arthritis sufferers have insisted that changes in the barometer and cold weather worsen their joint pain, and now new research backs them up.
"We see this all the time with our patients. People swear to their grave that the weather affects their arthritis," said Dr. Sam Lim, a rheumatologist at the Emory University School of Medicine in Atlanta. "But this is the first time we have nice, independent data that seems to correlate one with the other."
The researchers began by examining two separate sets of data -- one consisting of weather reports, and one of arthritis sufferers' pain reports. The scientists found that when they matched the weather to the ZIP codes of the patients, there was a strong correlation between changes in barometric pressure and increased knee pain. To a lesser extent, cooler temperatures were also associated with an increase in pain.
Results of the study were presented Oct. 17 at the American College of Rheumatology annual meeting in San Antonio, Tex.
The study's lead investigator, Dr. Timothy E. McAlindon of Tufts-New England Medical Center in Boston, said previous research efforts that have tried to document a link between weather changes and arthritis symptoms had been undermined by people's strong opinions on the matter; those biases influenced the reports. But by relying on sets of data that were independent of each other, the new study allowed the scientists to conduct a "robust" review that really does suggest an association between weather and aches and pains, he said.
Lim added, however, that it's important to note that, while the new research shows an association between weather and pain, "it doesn't mean that the weather changes cause an increase in pain. That's the next step."
For the study, the researchers merged data from an online glucosamine trial (a large-scale study of an over-the-counter arthritis treatment) with National Oceanic and Atmospheric Administration (NOAA) weather data. The glucosamine study, which was conducted across 41 states from 2000 to 2002, tracked 205 arthritis patients who reported on their arthritis pain for a three-month period.
Only after the study was completed did McAlindon and his colleagues begin to look at weather patterns where the study participants lived. The scientists first identified the nearest weather station by ZIP code for each of the study participants. Then they examined daily weather reports from NOAA that identified the temperature, barometric pressure, rainfall, and dew points for the locations of each of the participants for the three months they took part in the study. The scientists averaged the weather reports from one, three, and seven days prior to each person's report of pain, and then looked for any change in each measure in the 24 hours before each pain report.
They found that changes in barometric pressure had a strong association with knee pain, as did cooler temperatures, although to a lesser extent. Rainfall and dew points had no significant associations, the researchers said.
The American College of Rheumatology offers a helpful fact sheet on rheumatoid arthritis.