2.2.2. Opioid-Prescribing Behavior: Type and Formulation of Opioids, Indications

Physicians were asked about their opioid-prescribing behavior with two questions: (1) "Under which noncancer-related chronic pain conditions have you prescribed strong opioids for as the primary prescriber within the past 12 months?" and (2) "Which of the following strong opioid formulations are you currently prescribing for the treatment of chronic noncancer pain"? Regarding question 1, the list of suggested diagnoses was "chronic nonspecific low-back pain, osteoarthrosis, diabetic polyneuropathy, postherpetic neuralgia, phantom limb pain, disc prolapse, spinal stenosis, rheumatoid arthritis, fibromyalgia syndrome, secondary headaches, osteoporotic vertebral body fractures, chronic postsurgical pain, peripheral artery disease of the lower extremities, grade 3 and 4 pressure ulcers, chronic pain associated with fixed contractures, central neuropathic pain, chronic regional pain syndrome I and II, chronic pelvic pain associated with adhesions or endometriosis, chronic inflammatory bowel disease, primary headaches, functional disorders, chronic pancreatitis, craniomandibular dysfunction, persistent idiopathic facial pain, neuralgia (e.g., trigeminus) and multiple sclerosis" with the answer options "Yes/No/Does not apply". "Does not apply" was explained with "I haven't had a patient with this type of chronic pain condition.".

Regarding question 2, the list of selectable opioids included "morphine, buprenorphine, fentanyl, oxycodone, hydromorphone and tapentadol", each supplemented with the most common German trade names and the following prescribing options currently available in the German national formulary: "oral extended release/oral (or nasal or sublingual) immediate release/transdermal/or I do not prescribe this strong opioid at all". The opioids and their possible formulations were presented as a table with mandatory fields—excluding non-available combinations, such as transdermal and morphine. "Noncancer-related chronic pain condition" or "chronic noncancer pain" was printed in bold in question 1 and 2 of the survey, respectively. The answers to the indication questions were based on the German guideline recommendations for long-term use of opioids in chronic noncancer pain (LONTS) [13]. This guideline defines both evidence-based as well as consensus-based indications and contraindications for opioid therapy and was published in its current version prior to the survey.

#### 2.2.3. Physicians' Emotional Response to Patients' Demands for Dose Escalation

Each physician was further presented a case vignette in which a patient with nonspecific low back pain and longstanding opioid therapy asked for an increase in opioid dose even though there was no evidence of objective somatic deterioration. The exact wording of the vignette and the respective question are given in Table 4. The five options for a response on an emotional level can also be found in Table 4. "Yes" or "no" was the possible answer for each statement. All statements needed to be affirmed or denied.

#### 2.2.4. Risk Literacy

The physicians' medical risk literacy was assessed by administering an adapted version of the validated Critical Risk Interpretation Test (CRIT) [26]. The score of correct responses ranged from 0 to 5 with the latter being the highest possible degree of risk literacy.

#### 2.2.5. Piloting

The questionnaire used in this study was piloted with 11 physicians that regularly treated CNCP patients: general practitioners and pain specialists with varying degrees of experience, both in the outpatient and in the hospital setting. They answered the questions as study participants, and they were also asked to give comments on the comprehensibility and quality of the questions. With their feedback, the framing and wording of the survey questions were revised and optimized. Both the German original version of the questions analyzed here and the English translation can be viewed in the Supplementary Materials.

#### *2.3. Statistical Analysis*

The survey did not permit any non-responses to the questionnaire items; thus, all datasets were complete. The data were descriptively analyzed by frequency distributions and percentages. A binary logistic regression model was used to explore potential associations between non-guideline compliant opioid prescription behavior—using the prescription of oral/nasal ultrafast acting fentanyl for CNCP as an example—and independent variables that may affect prescriptions, such as age, gender, work experience, prescription of other substances, such as buprenorphine, and the presence of negative emotions (at least one of the four possible suggested negative emotions). For the insertion of the independent variables into the model, the forward stepwise method was used. *p* < 0.05 was considered significant. Data were stored and analyzed with IBM SPSS Statistics (version 27) (Armonk, NY, USA).

#### **3. Results**

#### *3.1. Recruitment of Participating Physicians*

IPSOS contacted successfully contacted 8820 physicians. Of the 734 physicians who were interested in taking part in the survey, 7 did not meet the screener criterion, i.e., regularly prescribing opioids for CNCP; thus, 727 were recruited for the survey. A further 125 physicians, who had originally agreed to participate, eventually chose to not take part in the survey. Of the remaining 602 physicians who started the survey, 2 left the survey prematurely and 600 completed the survey. In the end, 6.8 percent of the contacted physicians answered the survey (Figure 1).
