Effect of Perioperative CBT on Chronic Persistent Postsurgical Pain Among Breast Cancer Patients

This will be a single-center, prospective, double-blinded, randomized controlled trial. The study will randomize breast cancer surgery patients into two groups: one that receives perioperative cognitive-behavioral therapy (CBT) in addition to usual care and the other receives an educational program. The estimated duration for the main investigational plan (e.g. from the start of screening of the first participant to the last participant processed and finishing the study) is one year.

Aims and objectives:

The primary objective is to examine whether a perioperative CBT-based psychological intervention is effective at reducing pain intensity at three-month follow-up, in high catastrophizing patients undergoing breast cancer surgery, compared to an education program.

Secondary objectives of the study include examining whether perioperative CBT has a demonstrable impact on patients, compared to a time-matched education program, with regard to additional self-reported secondary outcomes, including quality-of-recovery, pain catastrophizing, pain interference, depression, and anxiety.

Participants and recruitment:

Adult patients who are undergoing breast surgery (defined as wide excision with magseed surgery or full mastectomy patients with or without axillary clearance) who are proficient in the English language will be eligible for inclusion. Patients will be enrolled at the outpatient clinic of the Department of Anaesthesiology and the Breast Health Department at the Mater Misericordiae University Hospital. All patients entering the screening phase of the study will be registered on a Study Patient Registration Log and a unique registration number will be assigned. Clinical data will be assessed to evaluate a subject's eligibility.

Patients eligible for participation will be evaluated approximately two weeks before surgery and asked for informed consent, and then asked to complete the Pain Catastrophizing Scale (PCS) [Sullivan M et al] by a member of the research team. Patients with high pain catastrophizing, defined as a score of ≥24 on the PCS, will be eligible for randomization to perioperative treatment with CBT or the education and mindfulness program. This cut-off is based on a previous study that showed a pre-treatment score of 24 or higher on the PCS best-predicted follow-up chronic pain ratings and work status after multidisciplinary treatment[Scott W et al] and has since been selected as an appropriate score cut-off in a perioperative CBT intervention in lumbar surgery patients [Scarone P et al]. More recently, this cut-off was also suggested to obtain the highest sensitivity and specificity to predict unfavorable outcomes after spinal surgery [Tuna T et al].

Randomization:

Patients will be randomized after they are included in the study, having consented and completed the PCS (and scoring scored ≥24), and two preoperative appointments will be scheduled with the patients in the intervention and control groups. Patients will be randomized to either 'CBT' or 'Education' group by using an online computer-generated block randomization. The patient study number and group allocation will be typed onto separate pages and concealed in sequentially numbered sealed envelopes. Block randomization will occur as follows; 12 subjects per block to ensure even numbers of participants in each arm of the study and the number of blocks that will be used is 4. Randomization will be performed by an independent third party. The randomization key/seed will also be held by an independent third party and investigators will not have access to this key/seed until the study has been completed.

The envelope will be opened by the treating psychologist to reveal the group allocation. Patients and members of the research team involved in data collection and analyzing the data will be masked to group allocation. The treating psychologist will not be blinded. Group allocations will be revealed immediately if there was a clinical concern.

All patients in both interventional arms:

All patients, irrespective of group allocation, will be routinely prescribed medications for pain control and will be referred for physical therapy on an out-patient basis, or other services, depending on clinical indications and personal needs.

Sample size, power considerations, and statistical analysis:

The primary outcome is the difference in the BPI average pain severity score and average pain interference score between the study groups, three months after surgery. A clinically important difference on the BPI is a 2 raw score reduction on the 11-point NRS [Wong K et al \& Marcus J et al \& Mease PJ etl al]. The standard deviation (SD) of BPI scores after breast surgery is in the order of 2.3 on this scale (Burckhardt CS et al). Taking a BPI score reduction of 2 as being clinically significant, then n=21 patients would be required each arm if Type I error=0.05 and Type II error is 0.2 (power 80%). Taking into account a 10% drop-outs rate, we propose to enroll 24 eligible patients in each group (N=48 total).

Baseline patient characteristics will be stratified by group and presented as mean and standard deviation (SD), median and first and third quartile, and count and percentage, as appropriate. Differences in baseline characteristics between randomized groups will not be statistically tested, whereas differences with the separate control cohort will be tested using the independent-samples t-test for continuous variables, and Pearson's chi-square test for categorical variables. In case of expected cell counts of less than 5, Fisher's Exact test will be used instead.

All patients randomized (i.e. those with a PCS score > 24) will be analyzed in an intention-to-treat analysis. To test for a difference between the CBT and control group in the BPI 'average' pain intensity scale at three months, linear regression will be used. Adjustment for the type of surgery, age, and education will be made and, if necessary, for other prognostic variables significantly associated with the outcome (i.e., acute postoperative pain intensity, the severity of catastrophizing, preoperative depression, preoperative surgical fear, length of current sick leave, pain duration).

Secondary outcome variables will be analyzed similarly to the primary outcome. For these, logistic regression analysis will be used to test for differences in proportions at three months postoperatively. For exploratory purposes, we will compare the outcomes of the patients in the two intervention groups with the outcomes of patients with low pain catastrophizing scores (i.e. those with a PCS score < 24) undergoing care as usual. Linear mixed-effects regression for the three groups will be performed with primary and secondary outcomes at the three postoperative assessment periods and controlling for preoperative values. This analysis will indicate whether high catastrophizing patients follow a similar trajectory of pain and functioning after breast surgery compared to non-catastrophizing patients.