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 existin g studies if the mixed results are due to limited statistical power (e.g. s mall sample sizes and restricted variability in weather indices) or the fai lure to consider individual differences. The current study addressed these weaknesses by having 75 RA patients (mean age = 52.7; 71% female) record th eir daily pain severity for 75 consecutive days. Objective weather indices including temperature, barometric pressure, relative humidity, and percenta ge of sunlight were obtained for the same dates from a local weather servic e. The results indicate that for the entire sample, pain levels were highes t on cold, overcast days and following days with high barometric pressure. Pain levels also increased as a function of change in relative humidity fro m one day to the next. Individual difference analyses revealed significant variability, between patients in their weather sensitivity patterns. In gen eral, patients with higher levels of self-reported pain demonstrated more w eather sensitivity. When considering the magnitude of these effects, howeve r, weather variables accounted for only a small amount of change in pain sc ores. This pattern was hue even for patients with the most pronounced pain- weather relationships. Thus, although weather sensitivity was found, the ef fect sizes were not clinically meaningful. (C) 1999 International Associati on for the Study of Pain. Published by Elsevier Science B.V.