The study was conducted at two multi-specialty centers: Toronto Western Hospital, University Health Network (UHN); and Women’s College Hospital; Toronto, Ontario, Canada. Research Ethics Board approval was obtained from both participating centers (Women’s College Hospital: study #2019-0024-B and Toronto Western Hospital: study #19-5164). Written informed consent was obtained from all participants. This study was registered prior to patient enrollment at clinicaltrials.gov (NCT03959787, Principal Investigator: Jean Wong, Date of registration: May 22, 2019).
All patients were assessed by a preoperative clinic nurse and anesthesiologist. There was no change in standard care regarding preoperative patient assessment and education. They were then recruited by a research assistant. A total of 100 patients were enrolled in the study from May 22, 2019 to October 2019. Eligible patients were: 1) English speaking adults ≥ 18 years of age presenting to the preoperative assessment clinic; 2) accessible for follow-up by telephone or email at 15 and 30 days postoperatively; and 3) able to provide informed consent. The exclusion criteria were: 1) patients unable to understand English; 2) patients on opioids for chronic pain; and 3) patients who had taken opioids in the past 30 days.
All patients were asked to complete a questionnaire in the preoperative assessment clinic to determine their baseline level of knowledge about safe opioid use after surgery. Patients were randomized to either: 1) intervention group - educational pamphlet and standard care, or 2) control group – standard care (no pamphlet). A research analyst who was not involved in the study created a computer-generated randomization list for each participating site. Randomization was performed with a 1:1 allocation to intervention and control groups. At each site, the patient assignments were kept in serially numbered, opaque-sealed envelopes according to the randomization schedule. The research assistant opened the envelope after the patient consented to participate in the study.
Patients allocated to the intervention group were given the education pamphlet to read in the preoperative clinic, and repeated the knowledge questionnaire immediately after reviewing the pamphlet. All participants were asked the same knowledge questionnaire by telephone or email at 15 and 30 days postoperatively. Additional questions were asked assessing compliance with guidance given in the pamphlet on safe opioid use and disposal (patient behavior questions) at 15, and 30 days (if still taking opioids). The total scores were recorded after each completion of questionnaire. There were no changes in the surgical, anesthetic, and postoperative pain management of the participants. Prescription of postoperative opioids was not affected by patient participation in the study. Due to the impossibility for placebo education for the control group, both the participants and the research assistants were not blinded to the study intervention. However, the statisticians and study investigators were blinded to the intervention.
The primary outcome was change in questionnaire score immediately after education compared with control (baseline score). The secondary outcomes were change in score over time, correct response to safe storage, disposal, and patient behavior responses. For the change in score over time; baseline score was compared with post-education score in the intervention group, at 15, and 30 days in both groups.
Every effort was made to maintain patient participation throughout the study period and achieve contact at 15 and 30 days postoperatively. Five attempts to contact the patient were made for each follow-up.
Education Pamphlet and Questionnaire Development
A literature search was performed to find any existing patient education materials and/or questionnaires assessing patient knowledge on opioids in the perioperative setting. The existing pamphlets available in the literature did not meet the needs of our study, and we developed an educational pamphlet specifically for surgical patients using infographics (Fig. 1A; 1B). The content of the pamphlet targeted the following domains: background information on opioid analgesics, alternative methods of pain relief, proper use of opioids; side effects, signs of overdose, risk factors for adverse effects; how to properly store, and dispose of opioids. These areas were directed towards addressing potential questions a patient may ask during use of opioids postoperatively. The pamphlet was designed with the following characteristics: brevity, plain language, with essential information for surgical patients. This was integrated into an infographic to increase readability and improve comprehension.
A questionnaire was developed to assess patients’ knowledge of safe opioid use after surgery (The “Safe Use Of Opioids Questionnaire”; Fig. 2) based on previous questionnaires.11,,, Our questionnaire has a Flesch Kincaid readability test score of 5.21, meaning a person with a grade 5 level of education can understand the content. There were 35 True/False questions and 3 multiple choice questions with a single correct answer, giving a maximum score of 38. Additional patient behavior questions were developed for use at 15 and 30 days postoperatively to assess how patients actually behaved when using, storing, and disposing of opioids (Supplemental Fig. 1).
We consulted a Patient Education specialist from the UHN Patient Education Department and Patient Partners Program for assistance in developing material which was patient-centered and easy for patients to read, understand and use. The Patient Partner also provided feedback on the pamphlet and questionnaire prior to performing a pilot study on 20 patients to test the readability and usability of the preliminary patient educational material. The pamphlet was modified based on feedback from the patients in the pilot study.
Statistical Analysis
To determine whether the education increases knowledge about safe use of opioids, the pre-education and post-education questionnaire results were compared between the control group and the intervention group. The primary outcome was analyzed using repeated measure analysis of variance (rANOVA). The assumptions of independent observations and normality was satisfied based on data set-up and examining the distribution of test scores. Sphericity assumption was tested with Mauchly’s test, with the result suggesting the multivariate test statistics should be used. Subject characteristics were compared using chi-square and Fisher’s exact test. The secondary outcomes were compared using pooled t-test for continuous variables and chi-square analysis for categorical variables. All statistical analyses were performed using SAS 9.4.
Sample Size
Our sample size calculation was based on detecting a clinically significant improvement of 20% between the intervention group versus the control group in the primary outcome of opioid questionnaire knowledge score. Based on preliminary scores from the pilot study; assuming a significance level of 0.01 and 80% power, and accounting for a predicted attrition rate of 0.3, we calculated that 50 patients per group were required.