The use of opioids trying to control chronic pain is more and more increasing, but, as a consequence, cases of overdose are more and more frequent. Since the risks of overdose have not been described in patients with chronic pain, yet, some researchers in the State of Washington have examined 9940 patients with chronic pain (prevalently at the back or at limbs) to whom three prescriptions of opioid analgesics had been made in three months. Patients affected by cancers have been excluded. During follow-up, which has averagely lasted 42 months, there have been 51 cases of overdose (intentional and non-intentional): 6 have resulted in death and 45 have not been lethal (out of these, 13 have been certainly ascribed to opioids and 32 have had, as a diagnosis, the “possible” overdose). With analyses adjusted for various potential confounders (presence of depression, previous abuse of substances, presence of comorbidities) it was seen that more recent prescriptions have been the ones more at risk of overdose (Hazard Ratio 8.4). As to dose, the comparison between a quantity of morphine lower than 20 mg a day and a dose between 20 and 50 mg has given a HR of 1.2; between a lower dose and a dose between 50 and 100 mg it has presented a HR of 3.1; between a lower dose and a dose higher than 100 mg it has presented a HR of 11.2.
The risk of overdose in the use of opioids is real and unfortunately it is frequent, both whether it is intentional or not. Unfortunately, we do not know well which is the cause and we cannot even leave the use of these precious allied away in the fight against pain. An editorialist suggests to evaluate the patient and his possible risks of overdose well (for example the presence of depression or a previous drug abuse) and to frequently monitor the use of drugs.
