Rheumatoid arthritis patients show weather sensitivity in daily life, but the relationship is not clinically significant

While the majority of rheumatoid arthritis (RA) patients report that their pain is influenced by the weather, studies examining the impact of weather on RA pain have yielded equivocal results. It is not clear from the existing studies if the mixed results are due to limited statistical power (e.g. small sample sizes and restricted variability in weather indices) or the failure to consider individual differences. The current study addressed these weaknesses by having 75 RA patients (mean age = 52.7; 71% female) record their daily pain severity for 75 consecutive days. Objective weather indices including temperature, barometric pressure, relative humidity, and percentage of sunlight were obtained for the same dates from a local weather service. The results indicate that for the entire sample, pain levels were highest on cold, overcast days and following days with high barometric pressure. Pain levels also increased as a function of change in relative humidity from one day to the next. Individual difference analyses revealed significant variability between patients in their weather sensitivity patterns. In general, patients with higher levels of self-reported pain demonstrated more weather sensitivity. When considering the magnitude of these effects, however, weather variables accounted for only a small amount of change in pain scores. This pattern was true even for patients with the most pronounced pain-weather relationships. Thus, although weather sensitivity was found, the effect sizes were not clinically meaningful.