LAS VEGAS – Treating comorbid depression gives "you the biggest bang for the buck" in the overall care and rehabilitation of patients with chronic pain, according to Dr. Michael Clark, director of Johns Hopkins University’s Chronic Pain Treatment Program in Baltimore.
"When you treat the depression," pain lessens and function improves, regardless of other treatments and the cause of the pain, he said (JAMA 2009;301:2099-110).
Dr. Michael Clark
Depression is common in chronic pain and generally thought to be its byproduct. But, at least in some cases, the depression comes first and seems to drive the pain. Depression itself increases the risk for chronic pain syndromes and is the best predictor of persistence. Depression is also associated with higher pain intensity and more comorbities (Psychol. Med. 2004;34:211-9).
"We don’t fully understand" the relationship, but pain perception and depression appear to share common brain pathways, which is "probably why there is so much overlap," said Dr. Clark, also vice chairman for clinical affairs in Hopkins’ department of psychiatry and behavioral sciences.
The message for psychiatrists, primary care providers, and others is to "think depression," especially when chronic pain does not improve or gets worse with standard treatments. If patients are depressed, "aggressive treatment to remission is key," he said at the Nevada Psychiatric Association’s Annual Psychopharmacology Update conference.
Tricyclic antidepressants and serotonin–norepinephrine reuptake inhibitors (SNRIs) "are our friends" because they treat depression and, unlike selective serotonin reuptake inhibitors, neuropathic pain, as well.
"Conventional wisdom is that you give low doses of antidepressants to treat pain, and that you don’t need higher antidepressant-type doses. But if you don’t get pain relief at lower doses, there’s nothing to say that you should not give higher doses," he said.
Duloxetine and venlafaxine are good SNRI options; it is easier to achieve a therapeutic dose with duloxetine, but venlafaxine was fewer cytochrome P450 interactions. Bupropion, a norepinephrine and dopamine reuptake inhibitor, seems especially helpful for fibromyalgia cognitive problems, Dr. Clark said.
Given how much they help chronic pain, "you would think antidepressants would be in the water of every pain clinic, but they are not," he said.
Instead, patients often end up in the polypharmacy jungle, prescribed benzodiazepines, sleeping pills, barbiturates, muscle relaxers, and other drugs which "do not help anything and ... mess them up. [Irrational polypharmacy is] a real problem," he said.
So are the ever-increasing doses of opioids likely when comorbid depression goes unrecognized and untreated. "The amount of opioids [these patients] come to us on is huge. It’s not unusual to see people taking 1,000 mg of oxycodone a day or more, and they’re still walking around," he said.
Opioid-induced hyperalgesia is a risk in those situations, but even at lower doses, opioids can do more harm than good in depressed pain patients, worsening their quality of life, disability, and state of mind. "If you want to use them, you’ve got to make sure that your patient doesnot have an active major depression," Dr. Clark said, noting that the goal of his pain program is "to get people off opioids, usually entirely."
If patients "are not doing well and they are on a bunch of stuff, whether it’s opioids or something else, you really have to think about if the medicine they are on could be contributing or causing all of what you see. You really should be taking people off these things and seeing what happens," he said.
Dr. Clark is a consultant for Eli Lilly.