Background: The role of nonspecific treatment effects in the outcomes of patients receiving interventions for pain has been the subject of controversy and interest. While the administration of placebo and its effects have been widely studied, the role of placebo and nocebo effects of active agents administered prior to or during interventional techniques has not been explored.
Objectives: The evaluation of placebo and nocebo effects of sodium chloride solution and active agents (midazolam and fentanyl) administered during interventional techniques.
Study design: Randomized, placebo-controlled, evaluation.
Methods: A total of 360 patients were divided into three groups, with Group I receiving placebo, Group II receiving midazolam, and Group III receiving fentanyl. At 3 months, information was obtained with regards to their impressions or the experience of the study, compared to their previous experiences with the treatment and sedation. They were asked to rate their experience as better, worse, or no change compared to their previous experience.
Results: Between 13% to 30% of patients across all three groups of the study, rated their pain relief following injection as better than their previous experience. A smaller proportion, 3% to 8%, of patients in all three groups rated their experience following injection as worse than their previous experience. The majority of patients, 67% to 79%, regardless of group, described no significant differences as compared to their previous experiences with sedation and treatment for cervical or lumbar facet joint pain.
Conclusion: In patients undergoing interventional procedures, sodium chloride solution, midazolam, and fentanyl produced placebo effects in 13% to 15%, 15% to 20%, and 18% to 30% of the patients respectively. Similarly, a nocebo effect was seen in 5% to 8% of the patients in the sodium chloride group, 8% of the patients in the midazolam group, and 3% to 8% of the patients in the fentanyl group. It is concluded that positive and negative effects may be seen either with placebo or active agents in 13% to 30% of the patients.