Impact of long-term use of opioids on quality of life in patients with chronic, non-malignant pain

Objective: The use of opioids in the management of non-malignant pain remains controversial. For many physicians, pain relief stemming from opioid use is not enough unless there is also a noticeable change in quality of life (QoL) and patient functioning. The impact of long-term opioid treatment on patients' QoL has been investigated in a limited number of trials, and these studies differ considerably with respect to their design and principal findings. This systematic review presents the results of these studies. Design and methods: MEDLINE (1966 to November/December 2004), EMBASE (1974 to November/December 2004), the Oxford Pain Relief Database (Bandolier; 1954-1994) and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched for relevant papers by combining search terms for function with terms for opioid analgesia, non-malignant and pain. Studies were eligible for inclusion if they met all of the pre-defined criteria specifying study design, population, intervention and outcome measures. Results: Eleven studies evaluated long-term treatment with opioids in patients with chronic, non-malignant pain and assessed QoL (N = 2877). Six studies were randomised trials and the remaining five were observational studies. In general, the former had higher Jadad rating scores for the quality of the paper than the latter. Of the four randomised studies in which baseline OoL was reported, three showed an improvement in OoL. Similarly, of the five observational studies, a significant improvement in OoL was reported in four. Conclusions: There is both moderate/high- and low-quality evidence suggesting that long-term treatment with opioids can lead to significant improvements in functional outcomes, including OoL, in patients with chronic, non-malignant pain. However, further methodologically rigorous investigations are required to confirm the long-term QoL benefit of opioid treatment in these patients, and to elucidate the effect of physical tolerance, withdrawal and addiction, which are all associated with long-term use of opioids, on patients' functional status.