[Effects of long-term opioid therapy on psychomotor function in patients with cancer pain or non-malignant pain]

Abstract

Objectives: Despite increasing use of oral opioids in cancer and non cancer pain, little is known about the effects of long-term opioid therapy on psychomotor performance. This study was designed to investigate the effects of long-term opioid analgesia on attention and reaction time in cancer pain and in non-malignant pain.

Methods: Three groups of patients (n=128) were studied: 48 patients on long-term opioid therapy (group O; including 33 patients with cancer pain and 15 patients with chronic non-malignant pain), 30 patients receiving non-opioid analgesic therapy for chronic non-malignant pain (group NO) and a control group (group K) of 50 patients without pain and analgesic therapy. Attention was determined by Brickenkamp's d2-test, continuous reaction time by Schuhfried's method (Wiener Determinationsgerät, Mödling, Austria). In addition, a modified questionnaire developed by Zerssen was used to determine the patient's current mood. Pain, fatigue and anxiety levels were estimated by visual analogue scales.

Results: Although no significant difference in attention/concentration could be demonstrated between the three groups, patients taking opioids performed Brickenkamp's test a little worse and also demonstrated a significant decline in this parameter with advancing age. Also, in cancer patients attention/ concentration was more impaired than in non-cancer opioid patients. Auditory and optical reaction times were significantly slower in patients on opioids than in the non-opioid analgesic group and highly significant slower than in the control group, while in the more complex combinations test no such difference could be demonstrated. In addition, a highly significant deterioration in reaction times with increasing age could be demonstrated for opioid patients compared to the other groups, while only a non significant prolongation was found between cancer and non-cancer patients on opioid therapy.

Conclusions: Long-term opioid therapy produces a slight (non significant) impairment of psychomotor performance in patients with cancer pain or non-malignant chronic pain. These effects become significantly more pronounced with increasing age and in patients with cancer pain, indicating a higher susceptibility of the elderly towards opioids. These results indicate that, particularly in older patients receiving long-term opioid for cancer oder non-cancer pain, careful evaluation of their effects on psychomotor function is necessary in order to estimate patient's ability to perform his daily activities. However, since opioid effects were only minimal in the non-elderly other factors like basic disease, opioid dose, physical condition and age seem to be of greater importance than the effects of opioids per se.