International Guillain-Barré Syndrome Outcome Study: protocol of a prospective observational cohort study on clinical and biological predictors of disease course and outcome in Guillain-Barré syndrome.
Importance There is an urgent need for biomarkers to monitor treatment efficacy and anticipate outcome in patients with Guillain-Barré syndrome (GBS). Objective To assess whether there is an association between serum albumin levels, a widely used and relatively easily measurable biomarker of health and inflammation, and the clinical course and outcome of GBS in patients treated with intravenous immunoglobulin (IVIG). Design, Setting, and Participants We used serum samples derived from a cohort of patients with GBS admitted to hospitals across the Netherlands participating in national GBS studies from May 5, 1986, through August 2, 2000. Serum albumin was measured from January 13 to 20, 2011. Analysis was performed from February 25, 2013, to September 6, 2016. All patients fulfilled the criteria for GBS and had severe disease (defined as not being able to walk unaided >10 m). Patients misdiagnosed as having GBS were retrospectively excluded from the study. Serum samples were obtained before and after IVIG treatment at 4 standardized time points from 174 patients. Albumin levels were determined by routine diagnostic turbidimetry and related to demographics and clinical course during a follow-up of 6 months. Main Outcomes and Measures Serum albumin concentration was determined before and after treatment with IVIG and related to clinical outcome: muscle weakness (measured by Medical Research Council sum score), respiratory failure (measured by requirement and duration of mechanical ventilation), and ability to walk (measured by GBS disability score). Results Serum albumin levels were determined in 174 patients with GBS (mean [SD] age, 49.6 [20.1] years; 99 males [56.9%]). Before treatment, the median serum albumin level was 4.2 g/dL (interquartile range, 3.8-4.5 g/dL), with hypoalbuminemia (albumin, <3.5 g/dL) in 20 (12.8%) of 156 patients. Two weeks after commencing treatment with IVIG (2 g/kg), the median serum albumin level decreased to 3.7 g/dL (interquartile range, 3.2-4.1 g/dL) (P < .001), and the number with hypoalbuminemia increased to 60 (34.5%) of 174 (P < .001). Hypoalbuminemia was associated with an increased chance of respiratory failure before (16 [36.4%] of 44, P = .001) or after (29 [54.7%] of 53, P < .001) IVIG treatment, inability to walk unaided (21 [35.0%] of 60 vs 6 [5.3%] of 114, P < .001), and severe muscle weakness at 4 weeks (Medical Research Council sum score, 31.8 vs 52.9, P < .001) and 6 months (Medical Research Council sum score, 49.4 vs 58.4, P < .001). Conclusions and Relevance Patients with GBS may develop hypoalbuminemia after treatment with IVIG, which is related to a more severe clinical course and a poorer outcome. Further studies are required to confirm that serum albumin can be used as a biomarker to monitor disease activity and treatment response to IVIG in patients with GBS.