Analysis of Risk Factors and Construction of a Prediction Model of Motor Dysfunction Caused by Limb Herpes Zoster

OBJECTIVE: To analyze the influencing factors of motor dysfunction in patients with limb herpes zoster and to construct a nomogram to predict the risk of this complication. METHODS: A total of 213 patients with limb herpes zoster in the First Hospital of Jiaxing from January 2015 to June 2020 were enrolled. The muscle strength of the affected limb was evaluated by the Medical Research Council (MRC) score. The muscle strength of the affected limb was less than grade 5, and lower than that of the contralateral limb (normal side) was defined as motor dysfunction. Univariate and multivariate logistic regression analyses were used to determine the influencing factors of motor dysfunction in patients with limb herpes zoster. The nomogram of the risk of motor dysfunction was drawn by R software. Discrimination and calibration of the prediction model were assessed by using the C-index and calibration plot. Internal validation was assessed by using bootstrapping validation. RESULTS: There were 58 cases in the motor dysfunction group and 155 cases in the nonmotor dysfunction group, and univariate analysis showed that the location of involvement (OR = 4.095, 95% CI: 2.097–8.466, P = 0.017), whether or not diseases were combined (OR = 0.520, 95% CI: 0.281–0.959, P = 0.036) and the number of affected centrums (OR = 0.336, 95% CI: 0.177–0.632, P = 0.001) were associated with the occurrence of motor dysfunction in patients with limb herpes zoster. Multivariate logistic regression analysis showed that upper limb involvement (OR = 3.811, 95% CI: 1.829–8.387, P = 0.001), noncombined diseases (OR = 0.493, 95% CI: 0.249–0.969, P = 0.041) and the number of affected centrums ≤3 (OR = 0.439, 95% CI: 0.218–0.881, P = 0.020) were independent influencing factors of this complication. The prediction model displayed good discrimination with a C-index of 0.72 and good calibration. A high C-index value of 0.71 could still be reached in the interval validation. CONCLUSION: This study used the clinical data available to establish a nomogram model for motor dysfunction of limb herpes zoster and found that motor dysfunction is more likely to occur in patient who meets upper limb involvement, combined diseases and the number of affected centrums >3. This kind of high-risk group should be intervened as soon as possible.