Pre-Existing Chronic Pain Influences the Severity of Acute Herpes Zoster Pain-A Prospective Observational Cohort Study

Objective. Pre-existing chronic pain has been associated with severe postoperative pain. To analyze the impact of chronic pain on non-surgical acute pain, a cohort of patients with acute herpes zoster was studied. Methods. Consecutive patients, who needed hospitalization because of an acute zoster infection, were characterized and compared according to their pain history. Pain intensity, pain-related function, analgesic consumption, and psychological and physiological characteristics were assessed as baseline parameters on the day of hospitalization. Pain intensity and functional restrictions were evaluated on day 1, 4, 7, and on the day of discharge. The analgesic consumption was recorded and scored for each of these days. A multivariate analysis was performed for individual predictors. Results. 59 patients were included; 25 patients (42.4%) had pre-existing chronic pain. These patients had more severe acute zoster pain on all assessment days and were more restricted in function, such as sleep quality and mobilization. There were, however, no differences in analgesic consumption. In patients without chronic pain, only the amount of analgesic consumption was associated with the severity of zoster pain. In contrast, in patients with chronic pain, the severity of the chronic pain, physical health, and the extent of neuropathic pain characteristics were associated with the intensity of zoster-related acute pain, while analgesic consumption was not. Conclusions. Patients with chronic pain had higher intensity of zoster-related acute pain. Furthermore, they showed more pain-related dysfunction and needed longer hospitalization than patients without chronic pain. These results go along with findings for acute postoperative pain.