and a normal one
Image by Betty Pace
Results of a small study suggest that long-term opioid treatment may not be the best option for pain management in adults with sickle cell disease (SCD).
The study showed that patients who received opioids long-term often fared worse in measures of pain, fatigue, and curtailed daily activities than patients who were not on long-term opioids.
Researchers reported these findings in the American Journal of Preventive Medicine.
“We need to be careful and skeptical about giving increasing doses of opioids to patients with sickle cell disease who are in chronic pain if it isn’t effective,” said study author C. Patrick Carroll, MD, of the Johns Hopkins University School of Medicine in Baltimore, Maryland.
“Too little is known about the effects of long-term opioid management of chronic pain.”
For this study, Dr Carroll and his colleagues enrolled 83 SCD patients—57 women and 26 men. All were 18 and older, and their average age was 39.
Twenty-nine of the patients had been prescribed daily, long-acting opioids to manage their pain. The remaining 54 patients weren’t on long-term opioids.
The patients filled out daily electronic pain diaries for 90 days. Self-reported levels of pain, physical activity, fatigue, and pain-related daily activity interference were recorded, along with self-reported levels of pain relief and medication satisfaction on a scale of 0 to 100.
Crises, pain, and fatigue
The proportion of days in vaso-occlusive crisis was significantly higher for patients who were on long-term opioid therapy than for those who were not—29% and 11.9%, respectively (P<0.01).
Patients on long-term opioids also reported significantly higher levels of crisis pain—60.6 and 41.0, respectively (P<0.001)—and non-crisis pain—34.5 and 10.3, respectively (P<0.001).
Patients on long-term opioid therapy had higher levels of pain-related activity interference, both on non-crisis days—24.9 and 7.4, respectively (P<0.001)—and crisis days—56.7 and 37.7, respectively (P<0.01).
And patients on long-term opioid therapy had higher levels of fatigue on non-crisis days—49.7 and 27.0, respectively (P<0.001)—and crisis days—66.1 and 53.0, respectively (P<0.05).
Central sensitization
The researchers also performed some standard measures of pain processing on the test subjects, which measured and averaged variables such as how intensely participants experienced unpleasant heat and pressure.
The team was particularly interested in the phenomenon of central sensitization, in which the central nervous system amplifies painful sensations.
Central sensitization may be one way that opioids can increase pain sensitivity, and it also may play a role in how SCD causes chronic pain, Dr Carroll said.
For example, one such measure of central sensitization uses repeated pokes from a mildly painful stimulus in succession. In people who have this hypersensitization, each poke is perceived as more intense than the last because the nervous system becomes progressively more sensitive to the pain.
Combining the data from several measures of central sensitization, the researchers used a scoring system that sets a normal measurement at 0 and rates how abnormal something is by how far the values move away from 0. They calculated a central sensitization index for patients on long-term opioids and those not taking them.
Overall, patients on long-term opioid therapy showed higher levels of central sensitization, with an index of 0.34, than those who were not on opioids, with an index of -0.10.
In patients who were not on long-term opioid therapy, the level of central sensitization correlated with the level of non-crisis pain. However, in patients who were taking long-term opioid therapy and also had higher levels of central sensitization and clinical pain, the correlation essentially vanished.
Dr Carroll said this was surprising and suggests the mechanisms of pain in SCD patients on long-term opioid therapy may be different from patients who don’t take daily opioids for pain.
Dr Carroll cautioned that this work is preliminary and should not lead to the discontinuation of long-term opioid therapy in SCD patients.
“We need to better understand how long-term opioid use affects pain sensitization and determine if certain people are more sensitive to these effects so we can prescribe the best treatment option for each individual patient,” Dr Carroll said. “We also need to learn more about how sickle cell disease may sensitize the nervous system.”
