Comorbidity of postural orthostatic tachycardia syndrome (POTS) and chronic fatigue syndrome (CFS) in an Australian cohort. The most interesting thing about this, from my perspective, is that it confirms the finding from Julia Newton's team late last year that a significant but quite small proportion of CFS patients have POTS: 11% in this new study (n=306) vs 13% in the Lewis/Newton paper (n=179). Newton's team used Fukuda to diagnose CFS, not sure about this one, which might of course affect the findings. Authors Reynolds GK, Lewis DP, Richardson AM, Lidbury BA. J Intern Med. 2013 Nov 9. doi: 10.1111/joim.12161. [Epub ahead of print] Affiliation Department of Genome Biology, The John Curtin School of Medical Research, The Australian National University, Canberra. Abstract OBJECTIVE: ... The aim of this study was to examine the relationship between demographic characteristics, autonomic functioning and fatigue levels amongst CFS patients with and without comorbid POTS. DESIGN AND SETTING: All patients presenting to Melbourne CFS Discovery Clinic between 2009 and 2012 completed a 20-min standing task as part of their initial assessment. Heart rate and pulse pressure were recorded at baseline, at 2 min intervals post-standing, at the end of the task and following a recovery period. Average heart rate and pulse pressure variability were calculated from this data. Age, gender, length of illness and self-reported fatigue scores were also recorded. POTS patients were diagnosed by an orthostatic increase in heart rate greater than 30 beats/min, concomitant symptoms of orthostatic intolerance and no orthostatic hypotension. Differences in autonomic functioning between POTS and CFS patients were compared using independent-samples t-tests, while logistic and linear regressions were performed to examine the contribution of autonomic functioning to task completion and perceived fatigue, respectively. RESULTS: Comorbidity of CFS and POTS (CFS-POTS) was observed in 11% (33/306) of patients. CFS-POTS patients were significantly younger (P < 0.001), had a shorter length of illness (P = 0.034), experienced greater task difficulty (P = 0.002) and were able to stand for significantly shorter periods compared to the CFS-only patients (P < 0.001). CFS-POTS patients experienced significantly lower baseline diastolic blood pressure (P = 0.002), and significantly higher heart rate and lower pulse pressures at each standing measurement. Early heart rate changes (P = 0.002) and overall heart rate change (P < 0.001) were significant predictors of completion status, whereas heart rate variability (P < 0.001) and female gender (P <0.001) were significant predictors of increased perceived task difficulty. CONCLUSIONS: Haemodynamic and demographic differences between CFS-POTS and CFS-only patients suggest that the former group reflects a distinct subgroup of the CFS population. The findings highlight the utility of screening younger patients with fatigue for POTS, and identified heart rate variability as an important marker of fatigue for CFS patients in general.