Instability of physical anxiety symptoms in daily life of patients with panic disorder and patients with posttraumatic stress disorder.

The present study examined severity as well as degree and temporal pattern of instability of DSM-IV-based bodily symptoms of anxiety (BSA) in daily life of 26 panic disorder (PD) patients, 17 posttraumatic stress disorder (PTSD) patients, and 28 healthy controls (HC) during 1 week, using electronic diaries. The ecological momentary assessment around every 3h during wake times was accepted well by patients. Compared to HC, patient groups exhibited elevated instability of BSA. BSA instability was more pronounced in PTSD than PD (p<0.005), even after controlling for mean symptom level. Numbers of symptomatic episodes were comparable in PTSD and PD, but the duration of symptom-free episodes was shorter in PTSD than PD. Results indicate that PTSD patients are particularly burdened by fluctuations in somatic symptoms of anxiety, implying perceived unpredictability and uncontrollability. Electronic diaries can be applied in innovative ways to provide novel insights into the phenomenology of anxiety disorders that may not be captured well by retrospective interviews and questionnaires.