Rainfall may not be associated with joint or back pain in older Medicare beneficiaries, according to an observational study published in the British Medical Journal.
Researchers retrospectively assessed 1,552,842 patients aged ≥65 years who consulted with a general internist, for a total of 11,673,392 outpatient visits between 2008 and 2012. For the purposes of this study, the investigators determined the number of outpatient visits for back or joint pain (including intervertebral disc disorders, nontraumatic joint disorders, osteoarthritis, rheumatoid arthritis, and spondylosis) occurring on rainy and nonrainy days. Adjustments were made for chronic conditions, geographic-fixed effects, and patient characteristics.
Eighteen percent of outpatient visits with a general internist (2,095,761) took place on rainy days. Between rainy and nonrainy days, there was a significant difference in the number of patients with joint or back pain in both the unadjusted and adjusted analyses (unadjusted, 6.23% vs 6.42% of visits [P <.001]; adjusted, 6.35% vs 6.39% [P =.05]). These differences, in addition to being “in the opposite anticipated direction,” were determined by the investigators to be “unlikely to be clinically meaningful.” No significant association was established between the number of joint or back pain claims and the number of rainy days during the week of each outpatient visit.
Insufficient data were available to determine each patient’s degree of disease severity, thus precluding the researchers from “definitively exclud[ing] higher rates of joint or back pain related to rainfall.” Other weather conditions (ie, humidity and temperature) were not analyzed in relation to joint- or back pain-related outpatient visits, presenting another limitation of this study
The investigators concluded that the persistent belief that joint or back pain is associated with rainfall “may reflect the tendency of people to perceive patterns where none exist.”
Jena AB, Olenski AR, Molitor D, Miller N. Association between rainfall and diagnoses of joint or back pain: retrospective claims analysis. BMJ. 2017;359:j5326.