The Influence of Chronic Pain on Number Sense and Numeric Rating Scale: A prospective Cohort Study

BACKGROUND: Several studies have demonstrated an association between chronic pain and impairment of cognitive capabilities. Since the number sense is one of the cognitive ability involved in the evaluation of pain intensity using some pain measurement tools, impairment of number sense may impact pain assessment. Therefore, the validity of number-based pain assessment tools should be re-evaluated. OBJECTIVES: This study aimed to determine whether number sense is altered in chronic and acute pain patients compared to healthy subjects. METHODS: Overall, 150 participants were recruited and divided into the three groups of controls, chronic and acute pain patients. Pain intensity was evaluated using numeric and verbal rating scales as pain assessment tools. Number sense was assessed using number naming, number marking, and line bisection tasks. Deviation from correct answers was measured for each task. RESULTS: Patients with chronic pain (migraine headache) had higher pain intensity scores than acute pain subjects. Chronic pain patients showed significant deviation from the expected responses compared to controls in the line bisection task. CONCLUSIONS: Chronic pain patients may have impaired number sense and may differently use number-based pain assessment tools in comparison with healthy individuals.