Kwekkeboom, K.L., Wanta, B., & Bumpus, M. (2008). Individual difference variables and the effects of progressive muscle relaxation and analgesic imagery interventions on cancer pain. Journal of Pain and Symptom Management, 36, 604–615.

To assess, among hospitalized patients with cancer-related pain, responses to progressive muscle relaxation (PMR) and analgesic imagery, including the impact of these interventions on pain-related distress and perceived control over pain

To examine the influence of ability, outcome expectancy, previous experience, and concurrent symptoms on the effectiveness of the interventions

Scripts relating to \"control conditions,\" PMR, and guided imagery interventions were recorded on a CD. The recorded voice was male, and the recording did not include music. The day 1 control recording consisted of identification of health team members, explanation of patient rights, and a description of various hospital services. The second control recording described exercise and other activities to maintain strength while hospitalized and presented issues for consideration in discharge planning. The PMR recording guided listeners in tensing and relaxing muscles in a series of 12 major muscle groups from head to feet. The analgesic, or guided imagery, recording asked listeners to scan their bodies to identify areas of pain and to imagine replacing pain with comforting sensations. Then the recording asked listeners to imagine putting their hand in an anesthetic fluid, feeling it go numb, and then transfer the numbness to painful areas of the body. All recordings were of similar length. Trials were done when current pain was rated 2–8 on a 10-point scale. Trials were delayed if patients had received an oral analgesic within one hour or an IV analgesic within 30 minutes. Patients with the option of patient-controlled analgesia were asked to refrain from increasing doses during the 15-minute trial and were maintained on basal continuous infusion. A control trial was the first trial done each day. If pain persisted at the end of the control trial, the research nurse continued with whichever experimental trial was assigned for that day. Two intervention trials were done each day, at least one hour apart. Patients completed pre- and post-trial ratings of pain intensity and related distress. For each outcome measured, scores were averaged across two control, two PMR, and two analgesic imagery trials. In cases where only one trial was completed, this score was used in analysis. Patients were randomly assigned to two different groups. In one group, PMR preceded imagery interventions; in the other, the sequence was reversed. All patients received the same control trials.

• The study reported on a sample of 32 patients.
• Mean patient age was 48.9 years (SD = 16.29 years).
• The sample was 55% female and 45% male.
• Of all patients, 55% had hematologic malignancy.
• All patients were Caucasian.
• The average number of months since diagnosis was 18.36 (SD = 33.32 months). Of all patients, 33% were receiving chemotherapy, 13% were undergoing radiotherapy, and 20% were undergoing combined therapy; 78% were being treated with a combination that included a strong opioid, a weak opioid, and nonopioid medications for pain management.

• Single site
• Inpatient setting
• Academic medical center in the Midwest, United States

The study used a crossover design with control.

• Scale of pain intensity (0 = no pain, 10 = worst pain imaginable)
• Scale of pain distress (0–10)
• Control Subscale of the Survey of Pain Attitudes
• Imaging Ability Questionnaire
• Outcome Expectancy Scale
• Edmonton Symptom Assessment Scale

• Compared to the control conditions, PMR resulted in greater change in pain intensity (Z = –2.15, p < 0.05) and pain-related distress (Z = –1.82, p < 0.05) and greater perceived control over pain (Z = –3.02, p < 0.01).
• Compared to the control conditions, guided imagery resulted in greater change in pain intensity (Z = –2.7, p < 0.01), change in pain-related distress (Z = –2.11, p < 0.05), and greater perceived control over pain (Z = –2.4, p < 0.01).
• PMR was associated with meaningful reduction in pain for 41% of participants. Imagery was associated with meaningful improvement in pain for 52% of patients. Authors defined meaningful improvement as an improvement greater than or equal to 30% reduction in pain intensity along with improvement in pain-related distress or perceived control.
• Compared to other patients in the study, those who experienced meaningful improvement with imagery had greater imaging ability (p < 0.05), more positive outcome expectancy (p < 0.05), and fewer concurrent symptoms (p < 0.05).
• The control condition was associated with some reduction in pain intensity and pain-related distress.

In only 50% of patients did PMR and guided imagery appear to have a more positive short-term effect on pain intensity, pain-related distress, and perceived control of pain than did simple distraction. Variables examined did not appear to influence the effects of PMR, but expectations and number of concurrent symptoms appeared to influence the effects of guided imagery.

• The study had a small sample size, with fewer than 100 participants.
• Interventions had very short-term effects on the outcomes examined. Authors did not state how long patients had been experiencing pain; whether patients were suffering acute, chronic, or episodic pain was unclear.
• Of all patients approached for participation, 41% declined to enter the study.
• Despite the crossover design, the study had risk of bias due to several factors.
  • Pain intensity measures were self-reported by patients.
  • Patients certainly knew the difference between the control and intervention recordings.
  • Analysis was limited to comparisons between responders and nonresponders; therefore, the capacity of the investigators to identify influencing variables was limited.
  • While changes in pain intensity showed differences that were statistically significant, whether the changes were clinically significant is unclear.
  • Many factors can affect the results evaluated (e.g., time of day, nature of hospital care, activities of the day). Investigators could not have accounted for or controlled for these factors.
  • The trial was extremely brief, only two days.

PMR and analgesic imagery, facilitated by a recording on CD, might be helpful to some patients to reduce short-term pain intensity, decrease pain-related distress, and increase sense of control over pain. However, much more evidence is needed before investigators can draw firm conclusions. These interventions could be implemented easily in a hospital setting and do not appear to harm patients. They appear to be more effective for individuals with greater ability to imagine, greater expectations of effectiveness, and fewer additional symptoms. This fact might lead clinicians to identify that group of patients most likely to benefit from such interventions.