Prevalence of neuropathic pain in one year survivors after intensive care admission

In critically-ill patients who have survived an intensive care unit (ICU)
admission, the reported prevalence of chronic pain is substantially higher than
in the general population. However, its etiology has not been studied.
Furthermore, it is unknown whether this pain has primarily nociceptive or
neuropathic characteristics. Discriminating between neuropathic pain and other
pain will provide clues regarding underlying pathophysiological mechanisms and
may guide improved treatment and preventive measures.

Our primary objective is to determine the prevalence of neuropathic pain within
one-year ICU survivors. A secondary objective is to compare patient and disease
characteristics between patients reporting neuropathic versus other pain, in
order to gain insight in possible risk factors for the development of
neuropathic pain.

Given the (almost complete) lack of prior knowledge about the topic, our study
is designed as an observational pilot study. In a subgroup of patients
reporting pain one year after ICU discharge according to a standard written
survey that is already routinely distributed among ICU survivors in the
University Medical Center Utrecht (UMCU), we will identify individuals with
(possible) neuropathic symptoms using an additional questionnaire and simple
physical examination.

The presence of pain in one-year ICU survivors is determined by analysis of the
routine follow-up questionnaire used at the ICU of the UMCU (METC protocol
number 10-006). Patients with pain one year after ICU stay will be contacted by
telephone and asked if they want to participate in a study investigating the
nature of their pain. After obtaining spoken informed consent, patients will be
visited at home. After obtaining written informed consent, the DN4
questionnaire will then be used to determine presence or absence of neuropathic
pain. Patients are also asked to rate the intensity of their pain on the
numeric rating scale (NRS) and visual analogue scale (VAS). To determine
physical, and especially muscle, function, hand grip strength will be measured
using a grip strength dynamo meter. Furthermore, some other questionnaires will
be filled out during this visit; the EuroQol 5D-3L (EQ5D) investigating
health-related quality of life (HRQoL), the hospital anxiety and depression
scale (HADS), and the impact of event scale (revised) (IES-R) investigating
symptoms of post-traumatic stress. These questionnaire and measurements will
take approximately 30-45 minutes and are completely non-invasive.