At baseline , patients with CFS had a lower number of steps per day ( P < .001 ) , digit span backward score ( P = .002 ) , and urinary cortisol to creatinine ratio ( P = .001 ) , and a higher fatigue score ( P < .001 ) , heart rate responsiveness ( P = .02 ) , plasma norepinephrine level ( P < .001 ) , and serum C-reactive protein concentration ( P = .04 ) compared with healthy controls .