No link between rainfall and visiting the doctor with joint pain

Study dispels belief that increased pain is due to “bad weather”

A study in the Christmas issue of The BMJ dispels the commonly held belief that changes in weather conditions lead to increased joint pain.

Many individuals believe that changes in weather conditions - including increases in humidity, rainfall, or barometric pressure - leads to worsening symptoms of joint or back pain, particularly among those with arthritis.

However, several studies exploring the relationship between various weather patterns and joint pain have reached mixed conclusions, including the possibility that people perceive patterns (eg, a link between rainfall and joint pain) where none exist.

So a research team led by Anupam Jena, Associate Professor at Harvard Medical School, compared daily rainfall data with outpatient visits to a general physician for joint or back pain for over 1.5 million Americans (aged 65 or older) insured by Medicare during 2008 to 2012.

Of the 11,673, 392 outpatient visits, 2,095,761 (18%) occurred on rainy days.

After taking account of several potentially influential factors, such as patient age, sex, ethnicity, and chronic conditions (including rheumatoid arthritis), they found the proportion of joint or back pain related visits was not associated with rainfall on the day of the appointment or with the amount of rainfall during that week or the preceding week.

For example, joint or back pain rates during weeks with seven rainy days were similar to weeks with zero rainy days.

In further analyses, there were no differences in the relation between rainfall and joint or back pain between geographic regions, age groups, or patients with and without rheumatoid arthritis.

 This is an observational study, so no firm conclusions can be drawn about cause and effect, and the authors outline some study limitations, such as lack of information on disease severity and use of over-the-counter painkillers, which would not be detectable in the data, and which could have influenced the results. 

However, they conclude that in this large analysis of older Americans insured by Medicare, “no relation was found between rainfall and outpatient visits for joint or back pain.”

A relation may still exist, they add, and therefore “larger, more detailed data on disease severity and pain would be useful to support the validity of this commonly held belief.”