Q J Med 2003; 96: 133-142
© 2003 Association of Physicians
The head-up tilt test with haemodynamic instability score in diagnosing chronic fatigue syndrome
From the Departments of Internal Medicine A and 1 Rheumatology, Bnai Zion Medical Center and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
Received 28 May 2002 and in revised form 2 December 2002
Background: Studying patients with chronic fatigue syndrome (CFS), we have developed a method that uses a head-up tilt test (HUTT) to estimate BP and HR instability during tilt, expressed as a ‘haemodynamic instability score’ (HIS).
Aim: To assess HIS sensitivity and specificity in the diagnosis of CFS.
Design: Prospective controlled study.
Methods: Patients with CFS (n=40), non-CFS chronic fatigue (n=73), fibromyalgia (n=41), neurally mediated syncope (n=58), generalized anxiety disorder (n=28), familial Mediterranean fever (n=50), arterial hypertension (n=28), and healthy subjects (n=59) were evaluated with a standardized head-up tilt test (HUTT). The HIS was calculated from blood pressure (BP) and heart rate (HR) changes during the HUTT.
Results: The tilt was prematurely terminated in 22% of CFS patients when postural symptoms occurred and the HIS could not be calculated. In the remainder, the median(IQR) HIS values were: CFS +2.14(4.67), non-CFS fatigue -3.98(5.35), fibromyalgia -2.81(2.62), syncope -3.7(4.36), generalized anxiety disorder -0.21(6.05), healthy controls -2.66(3.14), FMF -5.09(6.41), hypertensives -5.35(2.74) (p<0.0001 vs. CFS in all groups, except for anxiety disorder, p=NS). The sensitivity for CFS at HIS >-0.98 cut-off was 90.3% and the overall specificity was 84.5%.
Discussion: There is a particular dysautonomia in CFS that differs from dysautonomia in other disorders, characterized by HIS >-0.98. The HIS can reinforce the clinician's diagnosis by providing objective criteria for the assessment of CFS, which until now, could only be subjectively inferred.
Address correspondence to Dr J.E. Naschitz, Department of Internal Medicine A, Bnai Zion Medical Center, Haifa 31048, PO Box 4940, Israel. e-mail: Naschitz{at}tx.technion.ac.il