Prediction of Persistent Post-Mastectomy Pain

This study is a prospective observational study which phenotypes individuals' baseline pain, psychosocial and psychophysical characteristics, then measures perioperative and long-term changes to examine the relationship of psychophysical and psychosocial processing to persistent post-mastectomy pain development .

Preoperative Psychophysical assessment:

Pressure pain testing methods: After giving informed consent, the PI or a fully trained member of the research staff will administer a brief QST session. Pressure pain threshold and tolerance will be assessed using a digital pressure algometer (Wagner FDX, Greenwich, CT, USA) with a flat round transducer, probe area 0.785 cm2. Testing sites will be bilateral on the dorsal aspect of the proximal forearm (extremity site) and over the trapezius muscle at the upper back (truncal site). For pressure threshold determination, pressure is increased at a steady rate of approximately 1 kg/second until subject indicates that the pressure is first perceived as painful. Pressure pain tolerance will be determined by instructing patients to indicate the pressure at which the pain was no longer tolerable. Two trials will be performed at each site.

Temporal Summation testing methods: Mechanical pinprick pain will be assessed using standardized weighted pinprick applicators similar to those described by Rolke et al99 of two designated forces (256mN and 512mN) which result in a painful sensation in most subjects.1-2,100 First, a single stimulation of the lower force pinprick will be applied to the dorsal aspect of the index finger between the first and second interphalangeal joints of the each hand while resting palm down on the armrest, and then rated by the subject on a scale of 0-10. Next, after a break of at least 10 seconds, a train of 10 stimuli will be applied at the same premarked spot, at a rate of 1 stimulation/second. The subject will rate pain on a scale of 0-10 after the first, fifth and tenth stimulus, then rate any ongoing pain 15 and 30 seconds after cessation of the last stimulus. The same procedure will be repeated using the higher force pinprick on the third finger of the each hand. Subjects will undergo two trials at each force, with a break of at least one minute between trials.

Psychosocial Assessment: Preoperative demographic, medical, psychosocial and pain questionnaires will be completed by the patient during their preoperative office visit. Questionnaires assessing psychosocial factors are chosen based upon previous association with PPMP, strong psychometric validation characteristics, and brevity. The Pain Catastrophizing Scale (PCS), which has been validated in pain patients and controls, will be used to measure catastrophic thinking associated with pain. Depressive symptoms, anxiety and sleep disturbance will be assessed using short-form instruments from the NIH roadmap initiative, Patient Reported Outcome Measurement Information System (PROMIS), which have been extensively validated in studies comparing results with established scales, and have been calibrated on over 20,000 persons. The Brief Symptom Index 18-Somatization Scale, also previously validated in chronic pain patients,107 will be used to measure somatization.