The purpose of the present study was to investigate the relationship of weather sensitivity with clinical symptoms and structural abnormalities (via MRI of knee joints) in KOA patients. There were significant differences in WOMAC scores between the weather-sensitive and non-weather-sensitive groups. With the increase of the classification grade of WOMAC, the proportion of KOA patients in the non-weather-sensitive group was decreased, while the ratio of KOA patients in the weather-sensitive group was increased. As a result, KOA patients in the weather-sensitive group were more likely to have higher WOMAC scores compared with those in the non-weather-sensitive group. After the correction of baseline characteristics, weather sensitivity was found to be an independent risk factor for more severe knee pain, dysfunction, and overall clinical symptoms. This suggests that the presence of weather sensitivity increases the risk of severe knee pain, dysfunction, and overall clinical symptoms in KOA patients.
We found that there was a strong correlation between weather sensitivity factors and knee-joint pain and dysfunction in KOA patients. This result may have been due to weather-sensitive patients being more vulnerable to external climate change, thus aggravating the symptoms associated with KOA. Although a previous study reported that weather was not associated with pain(13), some studies have confirmed that weather factors are inextricably linked to knee joint pain(7, 8, 14–17). For example, in a randomized placebo-controlled trial of glucosamine, weather conditions were found to influence pain in OA patients(8). A two-week clinical study of European KOA also showed that weather-sensitive individuals suffered more joint pain than did non-weather-sensitive individuals with KOA(7). Another study has reported that weather can affect OA symptoms (pain and disability)(18).
In our present study, there were significant differences in the scores of cartilage and marrow abnormalities between the weather-sensitive and non-weather-sensitive groups. As the classifications of cartilage and marrow abnormalities increased, the proportion of KOA patients in the weather-sensitive group increased, while that in the non-weather-sensitive group decreased. Hence, compared with that in the non-weather-sensitive group, the weather-sensitive group was more likely to have higher scores of cartilage and marrow abnormalities. By correcting the baseline characteristics, weather sensitivity was also found to be an independent risk factor for more severe knee cartilage defects and bone marrow abnormalities. This suggests that weather sensitivity can lead to an increased risk of severe knee cartilage defects and bone marrow abnormalities.
In a study of Russian clinical samples, climatic factors were found to affect the radiological severity of OA patients(19). It is possible that weather-sensitive patients are more likely to be affected by climatic factors than are non-weather-sensitive patients, which may contribute to the physiological mechanism of joint degeneration(7).
Previous studies performed in the United States, Australia, and Europe have primarily focused on objective weather parameters rather than individual perceptions of weather, such as the relationship between self-perceived weather sensitivity and pain(7, 8, 15). Since the influence of weather on the human body varies across individuals, we focused on analyzing subjective self-perception of weather in KOA patients in our present study. Furthermore, by targeting weather correlates of interindividual differences in subjective experiences of pain, we also obtained objective evaluations of the relationship of self-perceived weather sensitivity with cartilage defects and bone marrow abnormalities in KOA patients. Our current study also included assessment of MRI scans of joint structure in weather-sensitive and weather-insensitive KOA patients. Our findings suggest that early treatment to weather-sensitive KOA patients may help in delaying their progression of knee joint degeneration.
Our present study also had some potential limitations. We only included cross-sectional analyses. The relatively small sample size of our study may also represent a limiting factor. Participants were defined as weather-sensitive individuals if they indicated that they experienced changes in knee joint pain or daily activities as a result of weather changes. If subjects noted that knee joint symptoms were not affected by weather changes, they were considered to be insensitive to the weather. However, our questionnaire on weather changes only considered temperature changes, whereas other weather factors were not considered, such as precipitation, atmospheric pressure, relative humidity, and wind speed(20). Therefore, clinical symptoms and changes in MRI features of the knee joint structures may be affected by these factors. Furthermore, a longitudinal study is needed to further clarify the relationship between weather sensitivity and KOA.