The effect of audio therapy to treat postoperative pain in children undergoing major surgery: a randomized controlled trial
To evaluate the analgesic effect of music and audiobooks in children undergoing major surgical procedures when compared to a control (silence) group.
The study was a prospective and randomized trial. Children undergoing major surgeries were randomized to one of the three groups: music, audiobook or control (silence). The primary outcome was the pain burden reduction by two treatments within 48 h postoperatively. Pain burden was measured using the area under the pain scale versus the 30 min interval for each treatment.
60 patients were recruited and 56 completed the study. Pain burden was reduced in the music and audiobook groups compared to control, median (IQR) of −60 (−90 to 0), −45 (−90 to 0) and 0 (−30 to 90) (min × pain score), respectively, P = 0.04. A linear regression analysis demonstrated an independent group effect on pain reduction even after adjusting for the mean pain scores recorded at the beginning of the treatment, slope of regression line −56.8 ± 24 goodness of fit r2 = 0.25 and slope significantly different from 0 (P = 0.02).
Audio therapy is an efficacious adjunct method to decrease post-surgical pain in children undergoing major surgeries. Audio therapy should be considered as an important strategy to minimize pain in children undergoing major surgery.
KeywordsMusic post-surgical painMusic treatment pain surgery children
The treatment of post-surgical pain in children often relies on the use of opioid analgesics [1, 2]. Due to the fear of opioid-related side effects such as respiratory depression, caregivers usually limit the amount of opioids given to children and this practice frequently results in poor post-surgical analgesic control [3–5]. In addition, the use of non-opioid drugs for pain control in children is commonly hindered by the lack of studies addressing efficacy and safety of those drugs in this patient population [6, 7].
The use of non-pharmacological therapies such as music has been evaluated with promising results to minimize pain in children . Nevertheless, prior studies focused primarily in the use of music therapy to minimize pain associated with short medical procedures such as venipuncture but not for the treatment of post-surgical pain [9–11]. The distracting and anxiolytic properties of audiobooks may also have a promising effect on pain control in children undergoing surgery but their efficacy remains to be evaluated . Currently, there is a lack of recommendation for non-pharmacological strategies by practice guidelines for the treatment of post-surgical pain in children .
The main objective of the current investigation was to evaluate the potential analgesic effect of music and audiobooks in children undergoing major surgical procedures when compared to a control (silence) group. We hypothesized that children exposed to music or audiobooks during the post-surgical period would have less pain than children in the control group.
Materials and methods
This was a prospective, randomized and controlled study. The study was approved by the Ann & Robert H. Lurie Children’s Hospital’s Institutional Review Board. Written informed consent was obtained from the guardians of all patients and assent was also obtained from children older than 8 years of age. Children aged from 6 to 18 years scheduled for major elective orthopedic, neurosurgical, urological, plastic or general surgeries at Lurie Children’s Hospital of Chicago, USA were recruited to participate in this study. Children were excluded if they were hearing impaired, mentally challenged and if they had chronic pain or opioids use.
Patients were randomized using a computer-generated table of random numbers to three groups: a music, an audiobook and a silence control group. Allocation was concealed by keeping the allocated treatment group in a sealed opaque envelope that was opened only after the child entered the study. Prior to surgery, if the patients were allocated to the music or the audiobook group, they were provided a playlist for music and a set of audiobooks to choose from. This allowed them to make their choice prior to any effects of anesthesia or surgery. The Audiobook group wore noise-canceling headphones (Etymotics; Elk Grove Village, IL, USA) connected to an iPod™ (Apple Incorporated; Cupertino, CA, USA) containing a selection of audiobooks and listened to an audiobook of their choice for 30 min. For the Music Group, a playlist from selections provided on an iPod™ was created. Children wore noise-canceling headphones and listened to their music for 30 min. The Silence control group received no intervention.
The Faces Pain Scale-Revised FPS-R, a validated scale to assess pain in children of 4 or 5 years old, was used to evaluate pain. Pain scores were assessed before treatment and 30 min after treatment within 48 h after surgery. The difference between post and pre-treatment pain scores was calculated as the main treatment effect for the study. This method accounted for differences in pain intensity among distinct surgeries and differences in analgesic treatments. The primary outcome was the pain burden reduction by the two treatments. Pain burden reduction was measured by the decrement in the area under the pain scale versus the 30 min time curve for each treatment using the trapezoidal method (Graph Pad Prism version 5.03, Graph Pad Software, Inc., La Jolla, Ca) . For all children, pain was treated according to the standard of the institution and adapted to the specific type of surgery and age. Other data collected included age, gender, surgical type and duration of surgery. All data were collected by a single investigator (SS).
In a one-way ANOVA study, sample sizes of 18, 18 and 18 will be obtained from the three groups whose means are to be compared. The total sample size of 54 subjects achieves 82 % power to detect differences with an effect size of 1 point difference in pain scores between groups and using a F test with a 0.01 significance level. The size of variation in the means is represented by their standard deviation which is 0.82. The common standard deviation within a group is assumed to be 1.5. 20 patients per group were recruited to account for possible drop outs. Power calculation was performed using PASS version 8.0.15, 2010 (NCSS, LLC, Kaysville, UT).
The Shapiro–Wilk and Kolmogorov–Smirnov tests were used to test the hypothesis of normal distribution. Normally, distributed interval data are reported as mean (SD) and were evaluated by one-way ANOVA. Non-normally distributed interval data and ordinal data are reported as median [interquartile range (IRQ)] using the Kruskal–Wallis H test. Post-hoc comparisons were made using the Tukey–Kramer or Dunn’s test with Bonferroni correction for multiple comparisons . Categorical variables were evaluated using the Fisher’s exact test. An additional exploratory analysis was performed by combing the audiobook and music groups (audio therapy) and median differences and 95 % confidence intervals of the differences in pain burden reduction were calculated using a 10,000 sample bootstrapping method. All reported P values are two tailed. A generalized linear regression model was also conducted to control for the treatment effect across different initial pain scores. Statistical analysis was performed using Stata version 12 (StataCorporation 2011. Stata Statistical Software: Release 12; College Station, TX: StataCorp LP.)
Baseline characteristics of the study groups
Music (n = 18)
Audiobook (n = 17)
Control (n = 19)
Type of surgery
Surgical duration (min)
Type of post-surgical analgesia
IV PCA opioids
Pain burden was reduced in the music and audiobook groups compared to control, median (IQR) of −60 (−90 to 0), −45 (−90 to 0) and 0 (−30 to 90) (60 min × pain score), respectively, P = 0.04. A pairwise comparison between the music and the control group did not achieve statistical significance after correcting for multiple comparisons (P = 0.055). We found that two patients in the audiobook, four in the music and three in control group received analgesic medications during the intervention, which demonstrated a balanced effect of potential confounders (P = 0.9).
The most important finding of the current investigation was the reduction in post-surgical pain in children exposed to music or audiobooks compared to control after major surgery. The reduction in pain burden was one point (0–10 scale) over 1 h of total treatment that the audio therapy groups received compared to control. Our results suggest that audio therapy should be available to minimize post-surgical pain in children undergoing major surgeries.
Our findings are clinically important because audio therapy is not currently implemented to reduce post-surgical pain in children undergoing major surgeries. In addition, practice guidelines for post-surgical pain control in children do not recommend the use of audio therapy as a method of analgesia control in children. To the best of our knowledge, this is the first randomized study to evaluate and demonstrate the use of patient-preferred audio therapy as promising non-pharmacological strategy to control post-surgical pain in children.
Another important finding of the current investigation was the detection of an effect in the audio therapy groups to minimize post-surgical pain irrespective of the baseline pain score. This fact suggests that audio therapy may not only be effective as an adjunct for major surgeries but also to less painful procedures performed in the ambulatory setting [16, 17]. Ambulatory patients cannot rely on potent and rapid acting intravenous drugs to minimize pain . After children are discharged home from the ambulatory surgical unit, parents can continue to use audio therapy to reduce post-surgical pain.
We did not detect a difference in the analgesic effect of music compared to audiobooks in the current study. It is possible that the distracting and anxiety relieving effect of an audio therapy may be responsible for the reduction in post-surgical pain regardless of the audio method utilized. Children can likely chose between the two methods according to their preference without significant detriment in the post-surgical pain control. Since anxiety and pain are often related, future studies to examine the efficacy of audio therapy on post-surgical pain should also include an anxiety assessment .
In contrast to opioid analgesics, the lack of side effects of audio therapy seems to pave a promising pathway for the implementation of this intervention for children undergoing major surgeries. We believe that costs associated with the audio intervention should not be considered a major barrier to implement the audio interventions to minimize pain in children undergoing major surgery. Improvement in analgesic control after surgery has been associated with improvements in important economic outcomes in the adult population such as reduction of hospital length of stay or unanticipated hospital readmission after surgery [20, 21].
We observed beneficial effects of audio therapy even in some patients who received epidural analgesia. It is possible that the pain reduction effect of audio therapy in those patients was mediated by a reduction in post-surgical anxiety [22, 23]. Unfortunately, we did not concomitantly measured anxiety as part of our study outcomes. Future studies evaluating the effect of audio therapy on acute post-surgical pain should include a validated anxiety measurement as one of their outcomes.
Our study should only be interpreted in the context of its limitations. We did not control for parent personality characteristics that could have affected children’s pain and anxiety . However; since subjects were randomized, we expected that those differences would be evenly distributed among the study groups. Due to the nature of our intervention, we were not able to blind patients and observers. Lastly, we did not include children younger than 6 years of age and our findings of the current study remain to be extended to that age group.
In summary, we demonstrated for the first time that audio therapy is an efficacious adjunct method to decrease post-surgical pain in children undergoing major surgeries. The type of audio therapy (music or audiobooks) does not seem to lead to significant clinical reduction in post-surgical pain. Due to the lack of side effects, audio therapy should be considered by hospitals and clinical practitioners as an important strategy to minimize pain in children undergoing major surgery.
The authors would like to thank Music Theory and Cognition Professor Richard Ashley, Northwestern University, Evanston, Illinois for his support of the study. Ann & Robert H. Lurie Children’s Hospital of Chicago; Northwestern University.
Conflict of interest