Within-Day Pain Profiles in Hospitalized Patients with Chronic Cancer-Related Pain: Implications for Inpatient Symptom Assessment

BACKGROUND: Within-day pain profiles in hospitalized patients with chronic cancer-related pain remain poorly characterized, limiting interpretation of inpatient symptom ratings. OBJECTIVES: To characterize within-day pain profiles in hospitalized patients with chronic cancer-related pain and explore clinical correlates relevant to symptom assessment. DESIGN: Observational cohort study. SETTING/SUBJECTS: This observational study was conducted in Japan and included 68 adult inpatients, comprising 38 with chronic cancer-related pain and 30 with chronic noncancer pain. MEASUREMENTS: Pain intensity was recorded on a 0-100 visual analog scale at six time points from awakening to bedtime over three consecutive days. Primary inference focused on within-day patterns within each cohort. Between-cohort comparisons were descriptive. Exploratory correlation analyses and a medication-related mixed-effects sensitivity analysis incorporating scheduled strong opioid use were performed. RESULTS: In the cancer-related pain cohort, the cohort-level pain profile remained relatively stable, with no significant time-of-day effect. The chronic noncancer pain cohort showed higher pain upon awakening and at bedtime and lower pain in the late morning. In the cancer-related pain cohort, higher 3-day mean pain intensity was associated with longer illness duration and higher Central Sensitization Inventory-9, Pain Catastrophizing Scale-4, and Patient Health Questionnaire-2 scores. The medication-related sensitivity analysis supported the within-cohort interpretation. CONCLUSIONS: Hospitalized patients with chronic cancer-related pain showed relatively stable cohort-level pain intensity under routine inpatient management. This stability should not be assumed to apply uniformly to individual patients. Inpatient pain ratings should be interpreted in relation to functional status, medication-related factors, treatment context, and inpatient conditions.