The present study divided adults, 30–59 years of age, into three groups based on their health status, to assess the relationship between health status and cold hypersensitivity over time, and to examine differences in indices between the groups.
With respect to sex differences in health status, we found more males in the healthy group (male: 57.8% > female: 42.2%), while the percentage of females increased with condition severity, such as in the SH2 group (male: 37.6% < female: 62.4%) (p = 0.029). Mean age was highest in the SH2 group (48.0 ± 10.3), followed by the SH1 (44.9 ± 8.6) and the healthy (41.0 ± 8.9) group (p < 0.001). These findings are consistent with an earlier study which reported that males take physical illness or injury less seriously and are less sensitive than females, and with an existing study that reported that an increase in age leads to physical and mental illnesses (30–32).
We found a significant positive correlation between health status and cold hypersensitivity that were followed up in two 6-month intervals, which indicates that having poor health results in having cold hypersensitivity. To identify the relationship between health status and cold hypersensitivity, the present study used logistic regression at baseline, adjusted for sex, age, and BMI. The BMI was included as it has been shown to have high correlation with cold hypersensitivity in previous studies on BMI and constitution type (33, 34). The results were similar in that when the participants’ health status was poorer, their probability of having cold hypersensitivity was higher. These findings are similar to those of another study reporting that a group of diseased patients had cold hypersensitivity on the exterior (35), and are consistent with poorer health status being associated with higher cold hypersensitivity scores (36).
The ARCLM results on health status and cold hypersensitivity showed that the stability coefficients of health status, expressed as autoregressive coefficients, appeared static over time. When health status was measured at three time points, the results showed that the health status at one time point had a significant influence on the health status at a subsequent time point. In other words, health status is not a transient state, but a state that persists over time. This is consistent with results from longitudinal panel surveys in middle-aged people, which have indicated that baseline health status does not show significant change over time (37, 38). Cold hypersensitivity also appeared to be stable over time, and the cold hypersensitivity at a specific time point had a significant influence on the cold hypersensitivity later. In other words, a person who has cold hypersensitivity does not have transient symptoms of cold hypersensitivity, but symptoms that persist over time. Our investigation of the cross-lagged effects of health status and cold hypersensitivity over time showed that health status had a stable and significant effect on cold hypersensitivity over time, while cold hypersensitivity had a partially significant effect on health status. These results indicate that poorer health status increases the probability of cold hypersensitivity. On the other hand, cold hypersensitivity did not appear to have a major influence on health status. These findings are similar to earlier results showing that the degree of phase angle (PA), which assesses health status by taking into account the condition of cell membranes, was lower in a cold-hypersensitivity group than in a non-cold-hypersensitivity group (38–40).
Several limitations of this study must be considered when interpreting the results. First, the sample population was relatively small, especially for a longitudinal analysis. However, all applicable longitudinal data were included without any exclusion criteria. The findings in the present study should be validated with a bigger sample population and a longer follow-up period. Second, the participants in the present study were restricted to faculty members from the Daejeon region in South Korea, which might limit the generalizability of the findings. The response rate to the questionnaire survey, however, was high and the survey included diverse age groups. Third, because health status and cold hypersensitivity were investigated using a questionnaire survey, there might have been limitations regarding the correct classification of the respondents due to implicit biases associated with self-reporting. However, many studies use self-diagnostic tools to measure various symptoms and diseases (20). Fourth, the measurement process was not comprehensive in scope and did not include social and environmental aspects. The findings are therefore limited to cold hypersensitivity, focusing on health status as an implicating factor. However, the relationship between the two non-recursive variables, health status and cold hypersensitivity, was empirically tested via three-wave bivariate autoregressive cross-lagged modeling.
The results of the present study identify health status as a variable that has a significant influence on cold hypersensitivity suggesting that future studies on the prevention and treatment of symptoms caused by cold hypersensitivity should focus on the patient’s general health status, along with other major variables.