Pain and Fatigue Interrelations in Terminally Ill Inpatients: A PCOC-Based Analysis

Pain and fatigue are among the most common and burdensome symptoms experienced by patients with advanced serious illness. However, few studies have captured their daily fluctuations using standardized, multidimensional tools.

This study aimed to examine the factors associated with daily pain and fatigue severity among patients with advanced serious illness using the palliative care outcomes collaboration (PCOC) framework in a Taiwanese palliative care setting.

A retrospective observational study was conducted at a medical center in central Taiwan between July 2021 and September 2023. Patients admitted to the palliative care unit underwent daily assessments using validated PCOC instruments. Generalized estimating equations (GEE) were applied to identify factors associated with daily pain and fatigue scores. Covariates included demographic factors, co-occurring symptoms, palliative care phase (PCP), functional status, and caregiver concerns.

Among 755 patients, fatigue and pain were the highest-scoring symptoms on the Symptom Assessment Scale. Pain severity was significantly associated with female sex, younger age, unstable clinical phase, sleep disturbance, appetite loss, bowel problems, and fatigue. Fatigue severity was linked to breathlessness, pain, appetite loss, and functional impairments, particularly in toileting and transferring among non-cancer patients. Subgroup analyses revealed differential patterns in cancer versus non-cancer populations. Specifically, we found that in cancer patients, fatigue was strongly associated with the unstable stage (phase 2), while this stage effect was not observed in non-cancer patients. Moreover, pain severity in cancer patients was more pronounced in females and younger patients, whereas in non-cancer patients, pain severity was more strongly linked to functional limitations (e.g., toileting ability) and psychosocial issues.

Using the PCOC framework for standardized patient assessment, we found that pain and fatigue are associated and comprehensive assessment is important as treatment of one may alleviate the other.