[Note: As with many studies pursuing potential diagnostic red flags for ME/CFS, research-trackers wonder how broadly they might apply given different diagnostic criteria - e.g., would these orthostatic abnormalities be even more evident in a more homogeneous diagnostic group (a subset)?]
Introduction: Autonomic dysfunction is common in chronic fatigue syndrome (CFS). This study set out to derive an autonomic biomarker using a comprehensive assessment of heart rate and blood pressure variability.
Methods: Heart rate and non-invasive continuous blood pressure measurements (task force monitor) at rest and on standing were performed in CFS (Fukuda n?=?68) and matched controls (n?=?68) to derive high frequency (HF; parasympathetic) and low frequency (LF; sympathetic) heart rate variability (HRV), systolic (SBPV) and diastolic (DBPV) blood pressure variability.
Variables of significance were combined using receiver operator curves to explore the diagnostic utility of parameters particularly at rest.
Results: At rest, LF-HRV (sympathetic) was significantly increased in CFS compared to controls, while parasympathetic markers were significantly reduced (P?=?0.006).
Total DBP spectral power was increased (P?=?0.0003) across all domains, with a shift towards sympathetic and away from parasympathetic SBPV (P?=?0.05).
On standing, overall SBPV response was significantly reduced with reductions in both sympathetic and parasympathetic components of SBPV (all P?0.0001).
Change in LF-DBP and relative balance of LF/HF DBP on standing differed between CFS and controls (P?0.0001).
Using the 85% sensitivity levels, we determined a threshold for three chosen resting BPV parameters of LF DBP >3.185, rest HF DBP >0.86, rest total DBP >7.05.
Achieving all of these differentiated between CFS and controls with 77% sensitivity and 53% specificity.
Conclusion: This study has shown that there are objectively measured abnormalities of blood pressure variability in CFS and that these abnormalities have the potential to be a bedside diagnostic tool.
Source: QJM, Jun 4, 2012. doi: 10.1093/qjmed/hcs085, by Frith J, Zalewski P, Klawe JJ, Pairman J, Bitner A, Tafil-Klawe M, Newton JL. NIHR Biomedical Research Centre in Ageing and Institute for Ageing and Health, Newcastle University, Newcastle, UK; Department of Hygiene and Epidemiology and Department of Physiology, Ludwik Rydygier Collegium Medicum, Bydgoszcz and Nicolaus Copernicus University, Torun, Poland. [Email: firstname.lastname@example.org]