Psychometric testing of a new Pain Assessment Behavior Scale (PABS)

 

Purpose:  To establish the internal consistency and construct validity of a new instrument to measure the presence and intensity of pain for patients who cannot self-report.

Conceptual framework: Nociceptive responses activated by pain produce measurable behaviors.  Some patients with pain are unable to use self-report instruments due to illness severity or cognitive impairment.  An observation scale that measures pain is postulated to have clinical and research utility.

Subjects:  A convenience sample of 316 adult men and women patients were recruited from three hospitals and a cancer institute in one urban medical center. All subjects provided a self-report about pain.  Patients with drug or alcohol abuse histories, or chronic non-malignant pain were excluded.

Method: Subjects were assessed at rest.  The patient’s pain behaviors were rated using the PABS. Subsequently, the patient was asked to give a numeric score to current pain with “0” representing no pain and “10” the worst pain.  Other variables collected included age, gender, race, pain type, and primary diagnosis.

Results:   Eleven patients were excluded post hoc leaving a sample of 305 subjects for analysis. The subjects were women (56%), African-American (70%) and Caucasian (29%) who were experiencing visceral (31%), bone/muscle (32%), incisional (29%), or neuropathic (8%) pain.  Subjects had medical diagnoses (53%), surgery or trauma (30%), or cancer (17%). The patient’s report correlated with the observed behaviors (r=.694, p=.000).  The reported pain score (mean=4.2 ± 3.5) was significantly higher than the PABS score (mean=2.16 ± 2.8) (t=13.08, p=.000). Internal consistency of this five variable scale is strong (alpha=.88).

Conclusions:  The instrument is reliable and performed well within and between diagnoses with both men and women.  A difference in pain scores may result from inflated self-reports or masked behaviors. Further testing is needed with subjects who cannot self-report.