It’s common to hear that people with joint pain feel its intensity increase when it rains. A new deep dive into data finds that weather conditions in 45 US cities are associated with Google searches about joint pain. However, researchers from UW Medicine and Harvard University say the increased searches and joint pain are more likely to be a result of increased activity levels when temperatures rise.
As temperatures rose within a span of 23 degrees to 86 degrees Fahrenheit, searches about knee and hip pain rose steadily, too. Knee-pain searches peaked at 73 degrees and were less frequent at higher temperatures. Hip-pain searches peaked at 83 degrees and then tailed off. Rain actually dampened search volumes for both.
The findings in PLOS ONE indicate that people’s activity level is likelier than the weather itself to cause pain that triggers online searches, say investigators from UW Medicine in Seattle and Harvard University.
“We were surprised by how consistent the results were throughout the range of temperatures in cities across the country,” said Scott Telfer, a researcher in orthopedics and sports medicine at the University of Washington School of Medicine. He collaborated with Nick Obradovich, a postdoctoral fellow in science, technology and public policy at Harvard.
The two used Google Trends, which reflects global use of the company’s search engine. They created keyword searches and phrases for hip pain, knee pain and arthritis, as well as a control search related to stomach pain.
From the 50 most populous U.S. cities, they sought daily summaries of local weather data from Jan. 1, 2011, to Dec. 31, 2015. The data included temperature, precipitation, relative humidity and barometric pressure – variables previously suggested as associated with increases in musculoskeletal pain. Five cities were dropped from the final results due to incomplete data.
Among the weather variables, only temperature and precipitation were found to have statistically significant associations, and only with searches for knee and hip pain. Searches about arthritis, which Telfer said was the study’s impetus, had no discernible correlation with weather factors.
“You hear people with arthritis say they can tell when the weather is changing,” Telfer said. “But with past studies there’s only been vague associations, nothing very concrete, and our findings align with those.”
Because knee- and hip-pain searches increased as temperatures rose until it grew uncomfortably hot, and rainy days tended to slightly reduce search volumes for hip and knee pain, the researchers inferred that “changes in physical activity levels” were primarily responsible for those searches.
“We haven’t found any direct mechanism that links ambient temperature with pain. What we think is much more likely explanation is the fact that people are more active on nice days, so more prone to have overuse and acute injuries from that and to search online for relevant information. That’s our hypothesis for what we’ll explore next,” Telfer said.
The interest in using internet data, he added, stems from the fact that web searches are increasingly people’s first response to experiencing adverse health symptoms.