The following issues make assessing substance abuse among patients who are receiving treatment for medical illness more difficult.
If cancer pain is not adequately treated, a patient may use drugs recklessly in an attempt to seek relief. Many patients may not receive effective treatment for their pain. When the prescribed treatment is adjusted and pain is controlled, the patient's need to use drugs in a manner in which they were not prescribed disappears.
Because the terminology used to describe drug abuse is not intended to include people without a history of drug abuse who are using medications therapeutically, many questions have yet to be answered. For example, while it is clear that a patient who forges a prescription, or injects a drug that was meant to be taken by mouth, is displaying deviant behavior, it is not clear if the same may be said about a patient who increases the dosage to control unrelieved pain, or takes a pain medication to fall asleep at night.
Health care professionals may make assumptions about the risk of drug abuse based on a patient's social group. If the patient belongs to a social group in which there is a high incidence of drug abuse, or if the patient has a history of drug abuse, it may be incorrectly assumed that the patient is at risk for abusing drugs prescribed for therapeutic purposes.
Substance abuse may be difficult to identify if the disease is progressing and causing the patient to have physical and mental changes. Treatment for disease may also cause these changes; radiation therapy to stop brain metastases, for example, can cause the patient to become withdrawn and experience mental changes.
To determine the cause of drug-related behaviors in patients who have advanced medical disease, the patients may be asked if the drug in question has been used at other times in the patient's life, whether drug use interfered with the patient's ability to complete treatment for the disease, and whether drug use prevented the patient from establishing a relationship with the health care team or family members.
The behavioral characteristics that are present in substance abusers, such as loss of control over drug use, compulsive drug use, and continued drug use despite harm, should be monitored in patients who are using drugs for medical conditions. Should a patient develop these behaviors, the health care provider should re-evaluate the patient's drug regimen.