Persistent pain in intensive care survivors: a systematic review

Background: According to earlier studies where the main aim has been quality of life, there is growing evidence of increased levels of persistent pain in survivors of critical illness. The cause of admission and several factors during intensive care may have associated risk factors for pain persistence. This systematic review aims to determine the incidence or prevalence of persistent pain after critical illness and to identify risk factors for it. Methods: Six databases were searched, and eventually nine studies were included in the final systematic process. The validity of observational and cross-sectional studies was analysed using the National Institute of Health `Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies'. Results: The incidence of persistent pain after intensive care varied from 28% to 77%. Risk factors for persistent pain were acute pain at discharge from ICU, higher thoracic trauma score, surgery, pre-existing pain, organ failure, longer length of ventilator or hospital stay, and sepsis. No difference in incidence between medical and surgical patients was found. Conclusions: New systematic, observational studies are warranted to identify persistent pain-related factors in intensive care to improve pain management protocols and thereby diminish the risk of persistent pain after ICU stay.