Introduction:
Post-intensive Care Syndrome (PICS) is a major health problem that describes impairment in physical, cognitive, or mental health status after critical illness. Chronic pain interferes with daily activities (ADL) and quality of life (QoL), and it is related to anxiety, depression and post-traumatic stress disorder (PTSD), conditions that are presented in PICS. Pain is a well-reported symptom in PICS and chronic pain is common after critical illness. Despite that, the role of chronic pain in PICS is not well documented. The aim of this study was to determine the prevalence and characteristics of chronic pain in critical illness survivors and evaluate its relationship with ADL and QoL. Additionally, we assessed the prevalence of anxiety, depression, and PTSD in this population and its association with chronic pain intensity.
Materials and Methods:
We conducted a prospective, longitudinal study, where patients were evaluated at 3 and 12 months later after ICU discharge.  Questionnaires evaluated were: Douleur Neuropathique 4 Questionnaire; Brief Pain Inventory Long Version; Hospital Anxiety and Depression Scale;  EuroQoL Test 5 dimension, 3 levels; and Post-Traumatic Stress Disorder Checklist – Civilian Version.
Results:
Assessing Brief Pain Inventory (BPI), at 3 and 12 months, 70,4 % and 72,4% of patients report some pain, with at least moderate pain that interferes with ADL in 35,2 % and 35,4% respectively. In the annual follow up evaluation of the EuroQoL scale 5 dimensions 3 Levels (5D/3L), the percentage of patients with problems in the evaluated dimensions was:  pain 65%, mobility 50%, anxiety/depression 50%, usual activities 23,9%, self-care 20%. Compared to 3-month follow-up data, there was an increase in the proportion of patients with problems in all dimensions except in usual activities. Also in the 12-month follow-up, patient with greater pain intensity (BPI Intensity Score> 3) reported the significantly worse value of EuroQoL visual analogue scale (VAS), more anxiety, depression and neuropathic pain, than patient with lesser pain intensity (p<0,05).  There was no statistical association between the diagnosis of PTSD and chronic pain intensity, but of all patients with PTSD, only 1 reported no pain.
Conclusions:
Chronic pain is common in critical illness survivors, interfere with ADL, and affect QoL and has to be considered as a part of PICS. Pain intensity is related to the presence of neuropathic pain, anxiety, depression and worse QoL.

DO WE HAVE TO CONSIDER CHRONIC PAIN AS PART OF POST-ICU SYNDROME? A PROSPECTIVE 12 MONTHS FOLLOW-UP STUDY