• Somnolence
• Fatigue
• Dizziness
• Clouded mentation
• Decreased ability to concentrate
• Slowed motor performance
• Slowed reflexes
• Increased response time to stimuli
• Impaired coordination

These cognitive opioid-related adverse effects could potentially impair patients’ abilities to drive or work safely. It seems reasonable to assume that a “normal” cognitive performance is a prerequisite for optimal performance of some tasks of everyday life, including the ability to drive and the ability to operate machinery. Furthermore, “normal” performance of cognitive functioning may well be associated with other aspects of “quality of life” such as tasks demanding vigilance, ability to concentrate, motivation, attention, and intact memory.

Statistics about the incidence of cognitive impairment due to chronic opioid therapy vary, depending on the literature reviewed, but do reinforce that it is a significant consideration¹. It is especially important to consider when first initiating opioid therapy, increasing opioid doses, or when prescribing with other drugs or substances that affect the central nervous system. For example, for cancer patients with chronic pain, these effects could be further compounded as a result of the disease state itself, and the concomitant cancer treatment.

Some epidemiologic studies and reviews suggest that motor vehicle accidents, motor vehicle fatalities, and citations for impaired driving, are not disproportionally associated with opioid use. One literature review² found that the majority of the reviewed studies (69.6%) indicated that opioids do not impair psychomotor abilities in opioid-dependent patients. In another study, cancer patients receiving chronic morphine therapy who completed a series of psychological and neurological tests to assess driving ability, were compared to cancer patients not on opioids. No significant difference was noted in their driving ability, but those patients on morphine tended to perform less well. The authors concluded that cancer patients receiving long-term analgesic medication with stable doses of morphine do not have psychomotor effects of a kind that would be clearly hazardous in traffic.³

Shortcomings of the evidence⁴ include reliance on cross-study comparisons (e.g., rates of opioid use in persons involved in motor vehicle accidents compared with estimates of opioid use in the general population), use of simulated and other controlled driving tests that may not completely mirror real-world driving conditions, and probable selection bias, as patients experiencing central nervous system opioid-related adverse effects are probably less likely to drive or to participate in studies that evaluate driving ability. No studies have evaluated the effects of chronic opioid therapy on work safety.

At issue, then, is what should be the clinician’s position regarding driving and work safety when maintaining a patient on chronic opioid treatment.

• First and foremost, clinicians should advise all patients who are initially prescribed chronic opioids, not to drive or engage in potentially dangerous work or other activities

• After beginning opioid treatment, or after a dose increase a patient should not drive for at least 4–5 days, possibly longer based on individual response

• Patients should be educated about the greater risk of impairment when they are starting opioid therapy, increasing their dose, and when they take other drugs or substances that may have central nervous effects, including alcohol, antihistamines, and other over-the-counter medications.

• Patients should be instructed to report whether they are experiencing sedation/unsteadiness/ cognitive decline, immediately to the physician, so that a reduction/modification in dosage can be initiated.

• Patients should be clearly instructed not to make any changes in their medication regimens without consulting their health care provider.

• Clinicians should counsel patients not to drive or engage in potentially dangerous activities if they experience any signs of impairment. Clinicians should be familiar with and describe the local state laws regarding physician-reporting requirements in these situations.

Clinicians should not necessarily take the position that being on opioids precludes driving⁴. In the absence of signs or symptoms of impairment, no clear evidence exists to suggest that patients maintained on chronic opioid therapy should be restricted from driving or engaging in most work activities. Some studies even suggest that cognitive functioning may improve due to better pain control.^5,6 Obviously, consideration needs to be given to the fact that some professions, such as taxi drivers or pilots, may restrict working while on chronic opioid therapy.

An important issue is what the health care provider should do if he/she is requested to complete forms that ask about the patient’s driving or work ability. In this situation, the health care provider should report the status of current research in the report. Additionally, the report should also include if with this patient there are any cognitive-related opioid side effects which may interfere with driving, or if there are none.

The clinician cannot guarantee safety, but must use their best clinical judgment. If there is a specific question about whether the patient can or cannot drive or operate machinery, that answer can be marked “unknown”, based on the inability to determine the answer in the absence of a simulator.

References:

1. Moore RA, McQuay HJ: Prevalence of opioid adverse events in chronic non-malignant pain: Systematic review of randomised trials of oral opioids. Arthritis Res Ther 7: R1046-R1051, 2005.

2. Fishbain DA, Cutler RB, Rosomoff HL, Rosomoff RS: Are opioid-dependent/tolerant patients impaired in driving related skills? A structured evidence-based review. J Pain Symptom Manage 25:559-577, 2003

3. Sjogren P, Thomsen AB, Olsen AK: Impaired neuropsychological performance in chronic nonmalignant pain patients receiving long-term oral opioid therapy. J Pain Symptom Manage 19:100-108, 2000.

4. Chou R, Fanciullo GJ, Fine PG et al. Clinical guidelines for the use of chronic opioid therapy in chronic noncancer pain. The Journal of Pain: Official Journal Of The American Pain Society 2009;10(2):113-130.

5. Jamison RN, Schein JR, Vallow S, Ascher S, Vorsanger GJ, Katz NP: Neuropsychological effects of long-term opioid use in chronic pain patients. J Pain Symptom Manage 26:913-921, 2003

6. Tassain V, Attal N, Fletcher D, Brasseur L, Degieux P, Chauvin M, Bouhassira D: Long term effects of oral sustained release morphine on neuropsychological performance in patients with chronic non-cancer pain. Pain 104:389-400, 2003