Biomarker-determined Alzheimer prevalence in patients undergoing surgery due to hip fracture

Maria Lönnquist1,*, Birgitta Kallberg1, Kaj Blennow1, Henrik Zetterberg1, Bengt Nellgård1

1Clinical Chemistry, Sahlgrenska University Hospital/Mölndal, Mölndal, Sweden

Introduction: Sahlgrenska University Hospital/Mölndal performs annually about 1000 operations on hip fractures, which makes it one of the largest orthopaedic hospitals in Europe. Hip fractures in the elderly may be complicated by clinical or pre-clinical concomitant Alzheimer’s disease (AD), which may increase the complication rate, including peri- and post-operative confusion and mortality. The mortality for patients who have undergone surgery because of hip fracture is about 7-9% during the first 30 days. The mortality after a year can be as high as 30%.

Objectives: We have collected lumbar cerebrospinal fluid (CSF) from 100 consecutive patients undergoing surgery because of hip fracture to determine the association of CSF biomarkers for AD with peri- and post-operative complications.

Methods: Prior to surgery, an assessment of the patient was carried out in order to be included in the study. Consent of the patient/relative was obtained and a study protocol established. According to the protocol samples were taken before surgery, 1 hour after surgery, 4 hours after surgery and also 3 days after surgery. CSF, serum, plasma and whole blood were drawn. The samples were aliquoted and frozen.

Results: The CSF will be analysed for T-tau (marker of axonal degeneration), P-tau (marker of neurofibrillary tangle pathology) and the 42 amino acid of amyloid beta (Abeta42, a marker of plaque pathology). This triplet of biomarkers is 85-95% sensitive and specific for AD neuropathology and will be used to address the question if AD neuropathology influences the risk of post-surgery confusion, cognitive impairment and mortality. Our results so far suggest that around 30% of patients older than 70 years of age have abnormal biomarker test results.

Conclusion: Positive biomarkers for AD neuropathology are very common in the elderly. If biomarker-determined AD neuropathology is a risk factor for peri- and/or post-operative complications, CSF analysis could be helpful to identify this risk group so that special precautions could be taken.

Keywords: Biomarker