[Clinical experience in opioid switch for noncancer chronic pain treatment].

BACKGROUND: The implementation of opioid switch (OS) as a strategy in non-malignant chronic pain has been scarcely proved. This article aims to evaluate the results of OS in a Pain Treatment Unit.

METHODS: This is an observational retrospective study in which all patients who had been subjeted to OS for a period of 18 months were selected. All of them had been treated with opiods plus adyuvants for more than 6 months and had a visual analog scale (VAS) of at least 5, either with or without adverse effects. Two variables were defined: clinical improvement, as a reduction equal or superior to 3 in VAS or the elimination of two or more adverse effects; equianalgesic dose reduction is the difference between initial and final opioid dose.

RESULTS: 7 out of 9 (77%) patients showed clinical improvement. Median equianalgesic dose reduction was 37% (-72% +18%). Five patients (55%) presented adverse effects to opioids before the OS but only one (11%) after OS.

CONCLUSIONS: OS was beneficial for the management of non-malignant chronic pain patients who have poor response to opioid treatment and/or with adverse effects. A secure OS should include a reduction in equianalgesic opioid dose. Prospective studys would achieve a mayor consensus for the applicance of OS in non-malignant chronic pain treatment.