Patients Response to Interventional Care for Chronic Pain Study (PRICS): A Cross-Sectional Survey of Community-Based Pain Clinics in Ontario, Canada

Background: Non-image guided injection treatments (“nerve blocks”) are commonly provided in community pain clinics in Ontario for chronic non-cancer pain (CNCP) but remain controversial. Aim: We explored patients’ perspectives of nerve blocks for CNCP. Methods: We administered a 33-item cross-sectional survey to patients living with CNCP pain attending four community-based pain clinics in Ontario, Canada. The survey captured demographic information and asked about patient experiences with nerve blocks. Results: Among 616 patients that were approached, 562 (91%) provided a completed survey. The mean age of respondents was 53 (SD 12), 71% were female, and the majority (57%) reported living with CNCP for more than a decade. Fifty-eight percent had been receiving nerve blocks for their pain for >3 years, 51% on a weekly frequency. Since receiving nerve blocks, patients self-reported a median improvement in pain intensity of 2.5 points (95% CI -2.5 to -3.0) on an 11-point numeric rating scale and 66% reported stopping or reducing prescription medications, including opioids. The majority who were not retired (62%) were receiving disability benefits and were unable to work in any capacity. When asked what impact cessation of nerve blocks would have, most employed patients (52%) reported they would be unable to work, and the majority indicated their ability to function across multiple domains would decrease. Conclusion: Our respondents who received nerve blocks for CNCP attribute important pain relief and functional improvement to this intervention. Randomized trials and clinical practice guidelines are urgently needed to optimize the evidence-based use of nerve blocks for CNCP.


Introduction
Chronic non-cancer pain (CNCP) has a high burden of illness, affecting approximately 20% of the population globally [1][2][3]. Chronic pain is associated with interference with physical functioning, daily activities, mental health, and social and family functioning and is a significant cause of lost productivity and disability in the workplace. The total direct (health care) and indirect (lost productivity) burden in Canada is estimated at $38-40 billion CAD annually. The direct healthcare costs are an estimated $15-17 billion CAD annually, which is approximately 10% of the total Canadian healthcare budget [3].
Medical management of chronic pain in Canada has generally focused on pharmacotherapy [4]. There are, however, increasing concerns regarding medication-related harms, particularly with opioids, as well as increasing awareness of the modest benefits of pharmacologic therapy [5][6][7][8][9][10]. Interventional procedures, such as non-image-guided nerve blocks, paravertebral blocks, joint, trigger point and scar injections, utilizing local anesthetic agents with or without corticosteroids, have been increasingly used in Ontario for CNCP. Ontario's tax-funded public health care plan (OHIP) reimbursed an estimated $420 million for nerve blocks in community and hospital clinics from 2011 to 2020 [11]. However, these interventions have come under criticism due to conflicting evidence for effectiveness and concerns that some physicians providing these services may prioritize revenue over optimal patient care [12][13][14]. Moreover, a 2021 draft standard from the College of Physicians and Surgeons of Ontario has proposed that, except for superficial facial nerve blocks, physicians administering nerve blocks for adult chronic pain must use image guidance [15]. We conducted a survey to assess patients' perspectives regarding nerve blocks for CNCP.

Materials And Methods
With the assistance of content experts, we developed a 33-item, English-language questionnaire to capture the experiences and impressions of patients with CNCP who receive nerve blocks (Appendix 1). Numeric rating scales for outcomes and questions from the Pain Disability Index were embedded in this survey. In January 2017, we conducted a pilot survey with 31 patients to evaluate if the questionnaire adequately measured views towards, and experiences with, non-image-guided nerve blocks for CNCP. The pre-test participants were also asked to comment on the clarity and comprehensiveness of the questionnaire and the time required for completion. Feedback resulted in minor wording changes in the survey to improve comprehension and the addition of questions regarding medication side effects, and the duration of pain relief after nerve blocks. The final questionnaire provided response options as checkboxes, as a previous report has shown that closed-ended questions result in fewer incomplete questionnaires compared to openended questions [16]. We also included an open-ended question to allow respondents to provide additional information if they wished to do so.

Questionnaire administration
Patients were recruited from four Canadian, privately owned, community-based chronic pain clinics in Ontario, NeuPath Centres for Pain and Spine. Approximately 80% of active patients attending these clinics receive therapeutic nerve blocks which pragmatically refers to a combination of specific peripheral nerve blocks, paravertebral blocks, trigger point, scar and joint injections, using local anesthetics, such as lidocaine, bupivacaine, ropivacaine, and mepivacaine, occasionally combined with steroids. About 20% of patients attending this group of clinics discontinued blocks within the first month due to lack of efficacy and 56% continued to receive blocks for at least one year.
From February 2019 to March 2020, all eligible patients attending each of the four clinics were notified, by mail or in-person, by the research team, and offered the opportunity to participate in our survey. Patients attending the clinic frequently (every two weeks or less) were approached in-person by administrative staff, and those attending less frequently were sent a letter by mail. The survey was administered at one clinic at a time for 4-6 weeks. Patients eligible to participate were (1) 18 years of age or older, (2) living with CNCP for >12 months, (3) currently receiving interventional nerve blocks, with a minimum of six treatments in the past six months, (4) fluent in English, and (5) provided written informed consent.
Patients were not excluded because of physical or mental comorbidities. Patients who agreed to participate were given a study subject number and advised that their answers to the survey would be confidential and their pain care would not be affected by their answers to the survey. Only the lead researchers (RJ and JB) and members of the research team had access to survey data and patients' treating physicians were unaware of who participated in the study. We originally planned to survey 1000 patients but discontinued recruitment prematurely due to COVID-19 restrictions. Our study methodology and survey were approved by the Advarra Institutional Review Board (https://www.advarra.com; project CR00142112).

Data management and storage
After eligible patients provided informed consent to participate, they were asked to complete the questionnaire during a regular treatment visit. Data was collected on an electronic tablet, using the Ocean software platform (https://www.cognisantmd.com). After providing instruction on the use of the tablet, research staff entered an anonymous participant code for each individual patient, who then completed the survey independently. Patients had an opportunity to review and edit responses prior to submitting their data. All survey data was automatically entered into a validated, password-protected, secure database that was only accessible to members of the study team.

Statistical analysis
We reported categorical data as proportions and continuous data as means and standard deviations (SDs) if normally distributed and as medians and interquartile ranges (IQRs) if not. We assessed the normality of continuous data with the Kolmogorov-Smirnov (K-S) test. As pain scores and quality of life scores were not normally distributed (K-S test p<0.001 for all values), we used a Wilcoxon matched-pair rank test to explore differences in median values within respondents and estimated the 95% confidence interval (95% CI) associated with the median change with the Hodges-Lehmann test. We performed all analyses using IBM SPSS 26.0 statistical software (Armonk, NY: IBM Corp). All comparisons were two-tailed and we used a pvalue <0.05 for statistical significance. Two of us (K-YH, MP) reviewed written comments independently and in duplicate to establish common themes and representative quotes. Any discrepancies were resolved by discussion.

Results
Among 616 subjects that were eligible for inclusion, 54 declined for a participation rate of 91% (562 of 616). The mean age of respondents was 53 (SD= 12), 71% were female, and approximately half were married. The majority (57%) had lived with CNCP for more than a decade and had been attending their current pain clinic for more than three years. Further, 31% of respondents had attended their current clinic for more than five years. The majority who were not retired (62%) were receiving disability benefits and were unable to work in any capacity ( Table 1).

No. (%) of respondents
Gender (    Prior to attending their current pain clinic, most respondents had received plain films (85%) and advanced imaging (e.g. MRI 85%, CT scan 67%). Almost all (95%) had seen a family physician, and many had previously attended medical specialists and surgeons regarding their pain. Most had received physiotherapy, massage, and chiropractic care. Almost all (99%) had been prescribed pharmacological treatments, and 28% had prior experience with nerve blocks. Self-reported side effects of the medication were common, with the majority endorsing dry mouth (69%), constipation (59%), impaired sleep (51%), and nausea (50%). Perceived helpfulness of prior referrals and treatments was highly variable, with the greatest endorsement for nerve blocks (median of 8 on a 10-point scale, . Sixty-six percent of patients self-reported stopping or reducing non-prescription and prescription medications since starting nerve blocks, including a reduction in opioid use (Tables 3-6).    2. The proportion of patients that reported stopping or reducing medication use was often inconsistent with the differences between previously and currently prescribed, which reflects a limitation of self-reported cross-sectional data.
NSAIDs: non-steroidal anti-inflammatory drugs 2023 Table 7 presents patients' experiences receiving nerve blocks at their current pain clinic. The majority of respondents (58%) had been receiving nerve blocks for chronic pain for greater than three years, at intervals ranging from weekly (51%) to longer than every three weeks (20%). Most respondents endorsed experiencing pain relief that lasted less than seven days. 2023 Table 8 presents patients' pain before and after nerve blocks. When asked to recall their average pain severity before and after nerve blocks in general, patients reported a median improvement on an 11-point numeric rating scale (NRS) of 2.5 points (95% CI= -2.5 to -3.0).
An improvement of 2-point is the minimally important difference for the 11-point NRS for pain [17]. Using this threshold, 74% of respondents (416 of 562) reported an improvement in average pain that met or exceeded the minimally important difference. Table 9 presents patients' quality of life before and after nerve blocks. Patients recalled low levels of functioning across a range of domains (e.g., occupation, self-care) prior to beginning nerve block treatments, ranging from a median of 1 to 4 on an 11-point NRS. They perceived important improvements in every domain because of their nerve block treatments, with median increases on the same scale ranging from 4 points (family responsibilities) to 2 points (sexual behaviour). Recreation (n=562) 2 (1 to 3) 6 (4 to 7) 3.5 (3.5 to 4.0) p<0.001 Social activity (n=562) 2 (1 to 4) 6 (5 to 8) 3.5 (3.5 to 4.0) p<0.001 Occupation (n=539) 1 (0 to 3) 6 (3 to 7) 3.0 (2.5 to 3.0) p<0.001 Sexual behaviour (n=537) 2 (1 to 4) 5 (3 to 7) 2.0 (2.0 to 2.5) p<0.001 Self-care (n=563) 4 (2 to 6) 7 (6 to 9) 3.0 (3.0 to 3.5) p<0.001 Life-support activities (n=563) 4 (2 to 6) 7 (6 to 9) 3.0 (2.5 to 3.0) p<0.001  When asked about the impact if the provincial government defunded nerve blocks for CNCP, most employed patients (52%) reported they would be unable to work in any capacity, the large majority indicated their ability to function across multiple domains would decrease, and most anticipated increased visits to their family physician and emergency department and greater use of prescription medication ( Table 11).

Written comments
Written comments regarding nerve blocks were provided by 378 respondents and these were grouped into six themes: (1) increased functioning, (2) improved mental health, (3) role in pain management, (4) improved quality of life, (5) decreased reliance on other pain relief methods, and (6) concerns regarding proposed defunding for nerve blocks for chronic pain ( "Nerve blocks saved me from a life of opioid addiction and gives me the ability to work and make an income to help support my family."

Discussion
Our survey of a group of adults with CNCP, attending four community-based chronic pain clinics in Ontario, Canada, found the large majority reported important and meaningful pain relief and improved quality of life that they attributed to the receipt of nerve blocks. The majority of respondents indicated that nerve blocks had allowed them to reduce or discontinue the use of non-prescription and prescription medications, including opioids. Reported adverse events associated with blocks were very rare. Patients reported that defunding of nerve blocks for chronic pain by the provincial government would have deleterious consequences. Despite these perceived improvements, most working-age patients were unemployed and receiving disability benefits.

Strengths and limitations
Strengths of our study include a high response rate (91%), providing assurances that our findings are likely representative of patients with CNCP attending the four community pain clinics in Ontario that we sampled, and the piloting of our survey prior to administration.
There are several limitations of this study. First, selection bias; our respondents, by inclusion criteria, were already responders to interventional treatments. Second, recall bias; our cross-sectional survey asked patients to remember their pain and functional status, and medication use, prior to starting nerve blocks and compared to their current status. As an example, respondents' replies to medications they had reduced or stopped due to nerve blocks were inconsistent with the difference between previously and currently prescribed ( Table 5). Third, financial conflicts of interest; this study was funded by a private pain clinic organization and the physician co-authors working in these clinics have a vested interest in the study results; however, all data and thematic analyses were conducted by an independent group at McMaster University. Fourth, our 33-item questionnaire has not been validated. Fifth, participants may have censored their answers to appear as "good patients" (i.e., social desirability bias). Sixth, the observational nature of our study design cannot establish causation between the receipt of nerve blocks and reported outcomes.

Relevant literature
Our respondents indicated a large net benefit with nerve blocks for CNCP: important reduction in pain and improved function and quality of life with few adverse events. Another cross-sectional survey of Ontario community-based pain clinics found similar results to ours [13]. However, self-perceived improvement in pain and function may not translate into employment, and most respondents in our sample were receiving disability benefits. At the same time, return to work may be influenced by other factors, such as time out of the workforce, bureaucratic barriers, lack of funding support for remedial skills acquisition, and concerns over losing wage replacement benefits [18,19].
All outpatient interventional pain clinics in Ontario are obligated to report serious adverse events that occur within 10 days of receiving treatment to the College of Physicians and Surgeons of Ontario Out of Hospital Premises Inspection Program (OHPIP). These include any patients being transferred to the ER after receiving a nerve block and all deaths from any cause within 10 days of treatment. Among the four clinics that administered our survey to their patients, there have never been more than 10 reportable events per yearthe majority being vasovagal events with spontaneous recovery after a short period of observation. There were no deaths attributed to treatment.
Our respondents self-reported reduced use of prescription medication, including opioids, after starting nerve block therapy. In contrast, a retrospective analysis of 47,723 patients in Ontario, Canada, who received nerve blocks for CNCP between 2013 and 2018 found no change in mean opioid dose between the year before and the year after starting nerve block therapy. This study did not rely on self-report but accessed the Narcotics Monitoring System which tracks all opioids dispensed in the province of Ontario. There were, however, within patient differences; specifically, 43% increased their use of opioids, 17% had no change, and 40% reduced their prescribed opioids one year after starting nerve block therapy [20].
In 2020, the National Institute for Health and Care Excellence (NICE) recommended against spinal injections for managing chronic low back pain due to the lack of supporting evidence [21]. Also in 2020, the American Society of Interventional Pain Physicians (ASIPP) released their updated guideline reaffirming recommendations in favour of radiofrequency ablation, nerve blocks and facet joint injections for chronic low back pain [22]. One challenge with interpreting the evidence of therapies for CNCP, including nerve blocks, is the role of non-specific effects.
Consider a 2013 survey of 260 patients with CNCP attending a tertiary multidisciplinary pain clinic in Ontario. The majority (88%) were receiving long-term opioid therapy and no patients were receiving nerve blocks or other interventional procedures; 74% reported >40% pain relief and 68% reported >40% functional improvement. Consistent with our findings, most of these patients (68%) were disabled from working and receiving wage replacement benefits [23]. A systematic review of 96 randomized trials of opioid therapy for CNCP was able to account for non-specific effects. This study found that 61% of patients allocated to opioids reported important pain relief, however, so did 49% of those randomized to receive a placebo [6]. The nonspecific effects of invasive procedures for CNCP are likely to be larger than pharmacotherapy [24,25].

Conclusions
Our survey found that people living with CNCP that pursue and choose to continue with, nerve blocks reported important and meaningful benefits in pain and function as well as reduced medication use (including opioids) with few adverse effects. While observational studies provide insights into the experiences of patients, they cannot establish causality. Rigorously conducted controlled trials of nerve blocks for CNCP are required to inform effectiveness and evidence-based guidelines for interventional procedures and chronic pain, informed by both current best evidence and patients' values and preferences, are urgently needed. All the information that you provide below will be entered only as anonymous statistical information in a database. No one will know the names of any individual patients completing the survey. 7. If you were treated at another pain clinic before CPM, which treatments did you receive there, and indicate how helpful each was.
• CT scan ☐1 ☐2 ☐3 ☐4 ☐5 ☐>5 (Check all that apply) • No, I am still on the same medications as I was before the nerve blocks.
• Yes, I have been able to stop or reduce the dosage of the following medications (check all that apply): • Topical rubs of 0-10, with 0 being "no pain" and 10 being "the worst pain imaginable"):
• No • Yes -please check all that apply below: • Nausea If you are working how much did nerve blocks help you to return to or stay at work?
(0 = no impact on working; 10 = a huge impact on being able to work) • "It has kept me mobile and I can walk longer distance" • "These blocks allow me to function, without them, I would be bed bound more or less, what is the point?" • "I am able to function (even for a short period of time), can complete hygiene with little assistance, enjoy quality time with my family (even for brief moments), depression/suicidal thoughts diminished -ceased trips (there were many) to Emergency room, and being stigmatized." • "I could not get out of a chair before. I could not function. I exercise in a pool now and I walk. Without the needles, I don't know what will happen to me." • "Without nerve blocks, I wouldn't be able to work, and I'd probably be dead by now." • "I am able to sit and stand for longer periods of time. I can be in the car and not be in pain constantly. I can do my own grocery shopping and some housework. I don't like the needles but it gives me 3-4 + days where I am not in constant pain. I need nerve blocks to help with the constant pain. Please continue with the nerve blocks." • "Without the nerve blocks, any activity involving standing, walking, sitting etc. would be limited to 3 to 5 minutes at a time. With the nerve blocks, the time increases to 30 minutes to an hour. Amazing improvement." • "They are a necessary to relieve pain, exercise, stretch and physically move my pelvis for walking, even sleeping." • " and more people will have to do the same, and that is something I thought the government wanted less people on opioids; not creating another opioid crisis." • "Having the nerve blocks have also helped the psychological dealing of pain and inabilities. It is a relief of being able to reduce pain medication by more than half the original amounts prior to blocks. I wouldn't want to have my life go in reverse of prior to the blocks.
The blocks enabling the not using a cane also eliminated the pain I was having in my shoulder from cane use. Being able to reduce medications of all types also eliminates the concern of future damage to the liver. Nerve blocks are also a good practice to help save lives from people dying of drug overdoses. I also feel that there would be less people shopping around for pain medication to help eliminate pain issues that nerve blocks help with. NERVE BLOCKS SAVE LIVES AND PROVIDE BETTER QUALITY OF LIFE!!!!!" • "I would be lost. I have been through a lot. This is my hope for a future. I would have to start looking into surgery options, increase my pain medication (I can't drive after taking medication), I would be home bound." • "Nerve blocks saved me from a life of opioid addiction and gives me the ability to work and make an income to help support my family." • "These nerve blocker treatments are absolutely essential to my quality of life. I will end up taking a high dose of opioid medication again, which I have put a lot of pain and effort into getting off of; leaving me nearly unable to function again, wasting my life away, in order to not be in severe pain. And I will also be taking up unnecessary space and resources at Emergency rooms. And, I just might entertain the idea of using street drugs to treat my pain, out of pure desperation. These are not acceptable options to me. Chronic pain is enough to drive any human being mad, and straight to suicide, which is why those of us who suffer from chronic pain do anything and everything we can to treat it. These nerve blocker injections are very painful, but we gladly take them because they are very effective. Or we would not do it." • "Nerve blocks have given me safe treatment options instead of using illegal medications. This has impacted my life in many other ways beyond just the treatment. It is a positive safe path to dealing with chronic pain, and without it, my life would be for the worse." with less importance that you could cut!"

Concerns
• "I would like to add that reducing this medical treatment is short-sighted. I suspect that visits to medical professionals will increase exponentially, that more medication will be prescribed, and the people afflicted with chronic pain will experience higher suicide levels.
The cost for this should exceed present levels of funding. I wonder if the bureaucrats and politicians can sleep with that on their collective conscience." • "Please do not stop the availability of nerve blocks. You have no idea what they do for us unless you were put in the same position. Please don't take away my life."