Relationship between Patient-reported Outcome Measures and Accelerometer-measured Physical Activity and Sleep in Patients with Post-herpetic Neuralgia

Abstract

Objective: Available treatment for chronic neuropathic pain is still limited, and the effect is modest. Thus, clinicians aim to improve activity and quality of life despite pain. The objective monitoring of activity is attracting attention in chronic pain assessments. Therefore, we objectively evaluated daytime activity and sleep in patients with post-herpetic neuralgia, using actigraphy to determine risk factors for decreased activity. Methods: Patients with post-herpetic neuralgia wore an actigraph (a wristwatch-like accelerometer) on the non-dominant hand. The actigraph measured day-time activity and sleep, which were compared with patient-reported subjective pain and sleep assessments. Results: Fifty-four patients with post-herpetic neuralgia who visited our outpatient clinic completed questionnaires and a week of actigraph monitoring. Subjective scores of pain intensity, neuropathic pain, disability in daily life, pain-catastrophizing thoughts, and insomnia were all well correlated. However, the actigraph-monitored activity levels, using two equations, and sleep quality were not associated with any pain- or sleep-related subjective scores. Discussion: The discrepancy between the subjective and objective scores in this study may be due to 1) features of post-herpetic neuralgia, an archetype of peripheral neuropathic pain affecting no motor nerves, 2) actigraph measurement limitations regarding the sedentary life of the elderly, or 3) activity misperception, a new proposition explaining the discrepancy between subjective and objective measures of activity, similar to the sleep state misperception. In patients with post-herpetic neuralgia, high pain intensity may be reported in those with highly maintained activity, in which treatment must be selected cautiously to prevent interruption of their physical abilities.