Identifying opioid dependence
The ICD-10 includes criteria to identify dependence. According to the ICD-10, opioid dependence is defined by the presence of three or more of the following features at any one time in the preceding year:
- a strong desire or sense of compulsion to take opioids
- difficulties in controlling opioid use
- a physiological withdrawal state
- progressive neglect of alternative interests or pleasures because of opioid use
- persisting with opioid use despite clear evidence of overtly harmful consequences.
There are other definitions of opioid dependence or ‘use disorder’ (e.g. the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, [DSM-5]), but the central features are the same: loss of control over use, continuing use despite harm, craving, compulsive use, physical tolerance and dependence remain key in identifying problems.
Is the patient experiencing pain or opioid withdrawal?
For a patient who takes codeine regularly, it can be difficult to differentiate between the re-emergence of pain and the emergence of opioid withdrawal symptoms. Pain symptoms often increase during opioid withdrawal. Some patients describe taking codeine as ‘the only thing that works’, for example in self-management of persistent or recurrent headaches. In some cases, a detailed assessment can reveal that opioid overuse or withdrawal itself may be the cause of the headaches (medication overuse headache, Box 3).1 In other cases, patients have always used the ‘strongest’ product available and have never tried taking simple analgesics without codeine.
Is the patient likely to need help in stopping codeine?
The assessment and management of patients who present with regular OTC codeine use is summarised in the Flowchart. Management approaches depend on the likelihood of opioid tolerance and dependence.
Patients who are unlikely to be codeine tolerant or dependent
Patients who are unlikely to be opioid dependent include those who have taken codeine intermittently for relief of acute pain, for example once a week or less often. For most people, simple OTC analgesics are as effective as combination analgesics containing low-dose codeine. A typical example of such a patient, Tom, is described in Box 4.
Management principle: for patients who are unlikely to be opioid tolerant or dependent, give brief advice on the changes in codeine availability and other options for management of acute pain.
Patients with possible codeine tolerance and withdrawal but uncertain dependence
Some patients may have been taking codeine daily or on most days for at least a month, but do not have clear features of opioid dependence, as in the case of Harriet in Box 5. These patients describe codeine use only in the context of managing their pain. They take doses in the recommended range (albeit for a longer period than recommended), and they may not yet have tried to cease codeine.
These patients may need medical assistance in ceasing codeine use. Reasons not to prescribe codeine or another opioid are outlined in Box 6.2 Depending on the patient’s level of codeine use, opioid tolerance, self-efficacy and resilience, either a trial of cessation with no medication or a short opioid taper assisted by a nonopioid medication may be appropriate. Alternative (nonopioid) pain management approaches should also be discussed.
Management principle: in the absence of a clear diagnosis of opioid dependence, support attempts at ceasing codeine.
How useful is the codeine dose in diagnosing dependence?
The case of Harriet in Box 5 demonstrates that problems with codeine can emerge even at recommended doses. The dose of codeine taken may help indicate the degree of dependence and the likely severity of opioid withdrawal symptoms. However, codeine has variable metabolism. About one in 10 people of Caucasian background are considered ‘ultra-rapid metabolisers’ of codeine, converting codeine into larger dose of morphine than usual and being at risk of toxicity. At the other end of the spectrum, 5 to 10% of the population are ‘poor metabolisers’ and cannot convert codeine into morphine, therefore experiencing little analgesia.3,4