PTA testing, the westmead post traumatic amnesia scale and opiate analgesia: A cautionary note

OBJECTIVE: To assess the validity of the Westmead PTA scale in patients treated with opiate analgesia. METHOD: Seventeen non-head injured, non-traumatic, electively hospitalized orthopaedic patients treated with opiate analgesia were tested on the Westmead PTA scale for a minimum of 2 consecutive days (n=17) to a maximum of 4 consecutive days (n=10). RESULTS: Only 20% of participants tested over 4 days reached criteria of three consecutive 12/12 scores on the Westmead PTA scale. Daily failure rates on the 12 item scale ranged from 36-70%. All failures were on the 'new learning' items, orientation items were never failed. CONCLUSIONS: The low pass rate of non-head injured patients treated with opiate analgesics indicates that the Westmead PTA scale is non-specific to traumatic brain injury and is probably an invalid measure of post-traumatic amnesia in patients actively treated with opiates. Implications for the measurement and accurate classification of traumatic brain injury patients are discussed.