Pain Management in Primary Care

Background and Introduction

Of the myriad problems that present to the primary care clinician, pain is the most common and arguably the most concerning. Since pain can herald something as serious as a heart attack or as routine as an inflamed carbuncle, primary care providers (PCPs) must answer the complaint of pain with alacrity and focused attention. Misdiagnosis can cause an unfavorable outcome for the patient; injudicious or inadequate treatment can undermine trust and devastate a therapeutic relationship.

Basic primary care principles have much to offer in the assessment and treatment of pain. The core values in primary care are compassionate care, embodied by the desire to help through the care of patients and their families; a holistic approach to the person that includes family, culture, and society; continuity of care through the maintenance of an interpersonal bond of trust and respect; reflective mindfulness, which manifests as self-awareness of one’s own thoughts and emotions with a sense of presence and attentiveness, and lifelong learning, a practice that requires iterative professional development with the goal of improved patient outcomes. Successful primary care incorporates care coordination, preventive care, access, competence, and appropriate utilization of community-based resources.

PCPs include physicians from the specialties of family, general internal medicine, pediatrics, and emergency medicine; some women also rely upon gynecologists for primary care visits. Recent decades have seen a change in the provision of primary care. The traditional model of a family doctor who knows the patient well and maintains continuity of care has evolved to include independent and collaborative practitioners at the same time that patients increasingly rely upon freestanding urgent care centers and hospital-based emergency departments (EDs). Thus

EDs and urgent care centers function as PCPs for both acute pain presentations and ongoing chronic pain treatment. However, patients seen in these settings are typically advised to follow up with their PCP, making collaboration with other healthcare providers inherent in the delivery of primary care pain management. Members of the primary care pain team include physicians, psychologists, physical therapists, advanced practice providers (nurse practitioners [CRNPs], physician assistants [PAs]), dietitians, exercise physiologists, and others. Specialist consultants for pain management likewise encompass many disciplines, including anesthesiology, neurology, orthopedics, palliative care, psychiatry, physical medicine and rehabilitation, and others.

The concept of a patient-centered medical home (PCMH) arose, in part, as a response to the increasing reliance on multiple healthcare venues and the subsequent potential for fragmentation of care. The Agency for Healthcare Research and Quality (AHRQ) of the United States Department of Health and Human Services characterizes a PCMH as providing comprehensive, coordinated, patient-centered care that is accessible, safe, and of high quality. Establishing primary care clinics or offices as advanced medical homes has been advocated by the American College of Physicians as a care model to provide patient-centered, physician guided care that links patients with a personal physician in the setting of a practice that provides focused, continuity care. This model is ideal for the successful management of pain since peripatetic, episodic contact with multiple health care providers discourages a holistic, coordinated, and inclusive treatment approach.

Patients with chronic persistent pain are some of the most challenging; they are likely to derive the greatest benefit from ongoing, focused care coordinated by a trusted clinician.

Physicians and other staff members within primary care practices have observed that the care of chronic pain patients can be onerous and burdensome, which may reflect a lack of formal education and training regarding pain medicine or inadequate systems for providing such care. Research evidence shows that PCMHs provide higher levels of adherence to treatment guidelines and screening recommendations. Such findings spotlight the need for coordinated patient care systems that provide support for the entire treatment team, including clinicians and staff members. ^, Besides the implementation of the PCMH model for pain treatment, an interdisciplinary approach is recommended; with input from appropriate collaborating medical disciplines, a multimodal approach to pain management may include nonpharmacologic, complementary and alternative medicine (CAM) techniques, behavioral therapies, non-opioid pharmacologic treatment, and when indicated and carefully managed, opioid analgesics.

See Chapter 4 , interdisciplinary outpatient pain care, for a detailed discussion of collaborative care for persons with pain.

This chapter is concern with the crucial responsibility that PCPs bear in evaluating, diagnosing, and collaborating with other clinicians to treat pain. The focus is upon the primary care approach to common pain conditions. Using low back pain (LBP) as a model, we will review the biopsychosocial approach to care; patient-provider communication; use of well-validated pain rating scales; and evaluation that includes a physical exam and functional assessment. The use of provocative maneuvers for determining the cause of pain, the development of a thorough differential diagnosis, and the selection of appropriate diagnostic modalities will also be discussed. Available and well-validated treatments for common pain conditions seen in primary care will be discussed. We will review the use of non-opioid and opioid therapies through the lens of continuity care and emphasize the importance of establishing a therapeutic relationship based on mutual trust and responsibility. Salient points from the Centers for Disease Control (CDC) guideline for opioid prescribing, which provides PCPs a basis for safe use of opioids in pain management, will be detailed.

Is Pain a Diagnosis or a Symptom?

It is tempting to view “pain” as its own diagnostic entity. There may be instances in which an etiologic injury, lesion, disease process, or other pain generator may not be readily evident (e.g. fibromyalgia). In contrast, some chronic pain states may have disease designations that specify causation, such as postherpetic neuralgia or painful diabetic peripheral neuropathy. ICD 10 includes designated G-codes for “chronic pain, unspecified” and “chronic pain syndrome,” which may be construed as useful and consistent with our current understanding of the neuroplastic change that can occur in the peripheral and central nervous systems to generate persistent pain.

However, the initial complaint of pain should always be viewed as a symptom needing careful assessment, not only of its physical manifestation but also its attendant psychosocial effects. Many PCPs hold the privileged position of having had long-term relationships with patients that enable them to assess biopsychosocial contributors to pain that go beyond its immediate physical expression. Experiences of pain have been linked to adverse childhood events (e.g. domestic violence, sexual abuse), which leave permanent yet invisible scars. It has been shown that attention and expectation have been linked to one’s experience of pain such that these behavioral traits may worsen or mitigate the intensity of how pain is experienced. The following quote, attributed to Sir William Osler, speaks to this fact: “ It is more important to know what kind of patient has a disease than what kind of disease a patient has.”

Developing rapport, trust, and understanding allows a full assessment of potential sources of pain (immediate, remote, or ongoing), development of a detailed differential diagnosis, and thorough medical workup that supports or confirms the pain source, which will lead to appropriate next steps in ameliorating or mitigating the patient’s experience of pain. Thus pain must be approached as a symptom, with the goal of identifying an accurate diagnosis to facilitate an effective treatment approach. PCPs must also recognize when a consult or referral to a specialist is needed and be ready to collaborate with other healthcare professionals in continuity care for the patient with pain.

Definitions and Types of Pain

In 2020, the International Association for the Study of Pain (IASP) agreed to modify its longstanding definition of pain, “An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.” A fourteen-member international committee voted unanimously to revise this term to: “An aversive sensory and emotional experience typically caused by, or resembling that caused by, actual or potential tissue injury.” The new language, which is supported by evidence-based understanding, highlights that the experience of pain is always subjective and can result from physical injury, tissue damage, or disease states but may also manifest as a reaction to a remote or potential injury. While pain is felt in specific part(s) of the body, there is an underlying and always unpleasant emotional component to the experience of pain, which may stem from psychologic trauma (e.g. adverse childhood experiences, sexual abuse) and/or injury-related experiences earlier in life. The new definition also acknowledges the fact that persons who are unable to verbally express themselves also suffer from pain.

The human experience of pain differs in intensity, quality, and duration as a result of pathophysiologic mechanisms with contributions from an individual’s psychological and emotional response. Pain embodies the holistic construct of mind-body-spirit, so a complete understanding of pain requires acknowledgment of the contribution of all three domains. Palliative care teaches that, in addition to physical pain, persons with serious illness and/or those who are facing the end of life experience pain that may encompass psychologic and existential or spiritual pain. Persons who are receiving palliative care that includes psychological support in addition to usual care report better quality of life and greater pain relief.

Pain can be characterized by its timing and duration, type, and location. In terms of timing, pain may be acute (sudden onset), recurrent (relapsing/remitting), or chronic (persistent).

Acute pain is a priority in terms of urgent evaluation, diagnosis, and treatment; it has an abrupt onset that is usually because of a specific cause and has a duration that is limited to three to five months. It represents a large healthcare burden in the United States because of several contributing factors, including about 40 million injury-related visits to EDs and approximately 100 million surgical procedures performed annually. Moreover, 80% of surgical procedures and accidental trauma result in acute pain that affects approximately 100 million individuals. Severe acute postoperative pain may be predictive of persistent postoperative pain, with clinical discomfort that is not referable to other causes (e.g. infection or pain from a preexisting condition) lasting two or more months post-surgery.

Table 75.1 is a partial list of common acute painful conditions that present in primary care.

Episodic, recurrent pain, such as that seen in migraine headache, can represent a unique treatment challenge for the PCP. Because of the unpredictable onset of the headache, some utilize EDs for acute treatment and only infrequently present to their PCP for acute and ongoing treatment.

Most acute pain resolves within a relatively brief timeframe, but it can sometimes persist to evolve into chronic pain. Research evidence has demonstrated that because of neuroplasticity of central nervous system regions involved in pain perception, delayed or inadequate treatment of acute pain can lead to the development of chronic pain. Recognition that untreated acute pain may evolve to chronic persistent pain is a mandate for PCPs to address acute pain as timely and effectively as possible.

Over half of patients with chronic pain are managed in primary care practices. Chronic pain is defined as nonmalignant pain persisting beyond the usual time needed for healing that has been present on most days for greater than three to six months. ^, According to the National Academy of Medicine (formerly the Institute of Medicine) white paper “Relieving Pain in America: A Blueprint for Transforming Prevention, Care, Education, and Research,” the prevalence of chronic pain in the industrialized world is projected to increase as a consequence of an aging population, rising rates of obesity (body mass index greater than 30), improved survival rates for catastrophic injuries such as spinal cord injuries and traumatic limb amputations, increased outpatient surgery with inadequate postoperative pain control, and better public understanding of chronic pain, all of which will increase the use of healthcare resources.

Table 75.2 presents a partial list of common chronic pain syndromes presenting to primary care.

Pain may be further categorized because of type, based on the etiology of the pain, as follows:

• Nociceptive pain is caused by an identifiable injury or disease process and may occur after thermal, chemical, or mechanical injury. In response to noxious stimuli, a message is transmitted via the primary afferent nociceptor axon from the periphery to the central nervous system (CNS), e.g. postoperative pain, myocardial or other visceral ischemia, bone fracture or metastasis, sprain or strain.

• Neuropathic pain is defined by IASP as “pain arising as a direct consequence of a lesion or disease affecting the somatosensory system. It develops as a result of damage to, or dysfunction of, the nervous system.” It is caused by damage to the peripheral and central nervous system by disease, injury, drugs, or deficiency, e.g. painful diabetic peripheral neuropathy, phantom limb pain, postherpetic neuralgia, B12 deficiency neuropathy, HIV neuropathy.

• Nociplastic pain is pain that occurs without evidence of an identifiable injury or inciting event. This new terminology was developed by IASP to define non-nociceptive/inflammatory, non-neuropathic pain, e.g. irritable bowel syndrome, fibromyalgia.

Patients may experience more than one type of pain at the same time. Examples include the patient with painful diabetic peripheral neuropathy (neuropathic pain) who also has hypertrophic osteoarthropathy of the knee (nociceptive pain); or the patient with shoulder pain that is found to be because of cervical spinal stenosis (neuropathic pain) who also has a longstanding history of fibromyalgia (nociplastic pain).

Pain Assessment

Effective pain management requires accurate assessment and diagnosis, but the first step toward resolving pain is gaining the patient’s rapport and trust. Since pain is subjective, clinicians must acknowledge the patient’s experience of pain by reassuring them that their complaint is valid and that their pain is real. A useful communication technique involves asking open-ended questions and then allowing the patient adequate time to describe what they are feeling and how it concerns them without interrupting or guiding the conversation. The technique of “ask-tell-ask” used by palliative care clinicians involves “asking” the patient what they feel and believe or understand to be the problem, then repeating to them what was heard with feedback or expanded information from the clinical perspective (“tell”), and then closing the loop by “asking” the patient to repeat what they understood to have been said.

Listening closely to how patients describe their pain can give insight into the type of pain and/or the possible pain generator(s). For example, colicky pain described as “cramping, pressing, crushing, or wrenching” may have a visceral source, while words like “sharp, aching, sore, tender” are indicative of somatic pain. A constant dull ache with an intermittent sharp pain that is provoked by movement suggests musculoskeletal strain or sprain. “Pulsing, throbbing, shooting, stabbing, burning, tingling, electric-shock like, crawling, numb” are descriptions that are characteristic of paresthesia and may indicate that the pain is neuropathic in origin.

During the decade of pain (2001–2010) in America, The Joint Commission mandated that pain be measured as “the fifth vital sign.” In response, several well-validated rating scales were developed and implemented, particularly in inpatient settings. Validated questionnaires include the brief pain inventory (BPI), and Wong-Baker faces scale, originally developed for use in children and utilized for nonverbal patients. The utility of these scales has been shown in multiple studies. However, in recent years the focus has shifted from assessment of pain using a numerical or visual scale to an evaluation of the effect of pain upon physical function. A basic assessment of physical function can be performed using the Katz activities of daily living (ADLs) scale, commonly used by geriatricians. The basic ADL functions are dressing, bathing/grooming, feeding, toileting, and ambulating. Eliciting measures of functional status is important since setting goals for analgesia ideally should target specific functional measures; e.g. does the patient hope to be able to run a marathon or do they simply want to be able to transfer from the bed to the commode without significant pain?

For evaluation of the effect of pain on functional disability, specifically with regard to LBP, the Oswestry LBP disability questionnaire has been well validated. The brief pain inventory-short form (BPI), in addition to directly assessing the severity of pain, also assesses interference of pain with work, sleep, mood, and enjoyment. However, it is not easily used for non-verbal patients or those with cognitive impairment. A differential assessment of dementia, its presenting neuropsychiatric symptoms, and the potential presence of pain is crucial to provide the correct treatment. ^,

The inability to verbally communicate does not negate the possibility that a person is experiencing pain. Thus tools required to adequately assess pain may differ depending on a patient’s age, condition, and ability to understand. These patients will require the use of alternative assessment tools such as the Wong-Baker faces scale or, in the case of dementia, the pain assessment in advanced dementia (PAINAD) scale. The evaluation and management of patients with dementia are discussed in Chapter 79 .

Table 75.3 lists pain assessment tools, and Table 75.4 is a modified version of the PAINAD scale.

Diagnostic Assessment

Besides the use of a pain scale for rating pain, the following questions are useful in diagnostic assessment:

• Is the pain constant, intermittent, or transient?

• What relieves the pain?

• What worsens the pain?

• Where is the pain localized?

• Does the pain radiate?

The location of pain is frequently a clue to the origin of the pain. The query “tell me where it hurts” can be modified for patients who can comply to “please point to where the pain is the worst.” Visual inspection and manual palpation of the area may yield findings that indicate the source of pain, such as an inflammatory process.

For patients who do not require urgent evaluation, a careful “hands-on” physical exam may provide clues to the painful stimulus. Manual palpation of body regions that are identified by the patient as painful may discover somatic dysfunction(s). Somatic dysfunction is defined in the glossary of osteopathic terminology, as “impaired or altered function of related components of the somatic (body framework) system: skeletal, arthrodial and myofascial structures, and related vascular, lymphatic and neural elements.” Somatic dysfunction is further characterized as acute or chronic; the former is an acutely painful lesion accompanied in early stages by vasodilation, edema, tenderness, and muscle contraction, while chronic somatic dysfunction is an impairment or altered function of inter-related parts of the somatic system, and is characterized by tenderness, itching, fibrosis, paresthesia, and contracture.

The mnemonic TART is used by osteopathic physicians to guide palpatory examination. TART stands for “tenderness, asymmetry of position, restricted motion, and tissue texture changes.” The presence of one or more of these findings points to somatic dysfunction, which may be because of the musculoskeletal lesion itself or secondary to disease or derangement in a body part within the same dermatome. Palpation of a painful body region may also reveal point tenderness or trigger points (focal areas of hyperalgesia) and other subtle clues to the etiology of the pain. Besides trigger points, palpatory findings may reveal altered skin turgor (swelling or bogginess) and/or asymmetry, such as decreased and/or painful range of motion. Asymmetry of the musculoskeletal structures may be because of splinting, favoring, or compensating for the pain generator. Examples of somatic dysfunctions directly associated with musculoskeletal injuries include acute psoas muscle spasm (LBP) or tendon stretch/strain (sprained ankle). Passively moving an affected body part through its normal range of motion may reveal a restriction or physiologic barrier. The term somatic dysfunction has been used as a diagnosis. However, many authors feel that its relevance lies not in naming a diagnosis but rather as a descriptive physical finding. ^, Osteopathic manipulative technique (OMT) is directed at restoration of normal anatomic position, range of motion, and function of body structures.

Somatic dysfunction can also occur secondary to neuronal pathways that are “facilitated” or upregulated because of an underlying condition in an organ or viscera. In this case, superficially palpated lesion(s) may signal disease or dysfunction remote from the physical finding, a condition referred to as viscero-somatic reflex. ^,

Thus identifying pain’s origin solely by its location may be confounded by the phenomenon of referred pain, which is pain felt in one part of the body that is caused by injury or disease of internal structures or organs (e.g. shoulder or upper back pain caused by acute cholecystitis). Viscero-somatic reflexes are representative examples of referred pain. The physiologic mechanism is thought to involve the convergence of multiple sensory neurons on the ascending spinothalamic tract, causing the inability of the brain to distinguish visceral pain signals from more common signals arising from somatic receptors.

Examples of pain that is referred to the back are found in Table 75.5 .

Besides localized or referred pain presentations, the location of pain may be diffuse, as seen in fibromyalgia or irritable bowel syndrome. These pain conditions are examples of nociplastic pain, in which the pain location does not specifically point to a diagnostic process.

See Chapter 37 on chronic widespread pain.

Reassurance that a complaint of pain is valid and warrants concern is the first and ongoing step in the treatment of chronic pain. While complete elimination of the pain may not always be possible, there are several nonpharmacologic and pharmacologic options for the treatment of chronic pain. An optimal outcome relies upon careful selection and trial of appropriate medications coupled with adjunctive therapies such as cognitive behavioral therapy, lifestyle modification, OMT, massage, physical therapy, and others.

Model of Pain in Primary Care: Low Back Pain

Since fundamental principles of low back pain (LBP) management are applicable as an initial approach for many pain presentations in primary care, LBP will serve as an exemplar for diagnosis and management of acute and chronic pain. This approach includes:

• focused triage to determine urgent/emergent status;

• biopsychosocial history and physical examination based upon patient rapport and trust;

• comprehensive, appropriate diagnostic workup;

• selection and application of appropriate therapeutic modalities;

• therapeutic trial(s) with frequent follow up evaluations of efficacy; and

• referrals and consultation(s) as indicated.

A further complete and detailed description of the etiologies and treatment options for LBP is available in Chapter 29 .

A review of the major causes of disability in the United States, including spinal cord injury, stroke, limb loss, and other catastrophic events, found that back pain and arthritis are the leading causes of disability. Most people will experience at least one episode of LBP during their lifetime; as noted, most episodes are self-limiting and, with conservative treatment, will resolve within weeks. However, many patients experience recurrence(s) and up to 44% report further episodes within a year; approximately 2% to 7% will go on to develop chronic LBP. ^, PCPs provide the initial evaluation and treatment in 65% of cases and frequently provide the ongoing care as sole providers for patients with LBP .

LBP can be categorized as acute (immediate onset with less than four weeks’ duration), subacute (slow onset with four to 12 weeks’ duration), chronic (greater than three months’ duration), or recurrent (LBP that reoccurs after a pain-free interval). A summary of LBP diagnostic recommendations in a joint clinical practice guideline from the American College of Physicians and the American Pain Society supports initial triage of patients into one of three broad categories: non-specific LBP; LBP potentially because of spinal stenosis or radiculopathy; or LBP potentially associated with another specific spinal issue for which prompt assessment is necessary or for which there is specific treatment needed. A published review of 15 clinical practice guidelines regarding the initial assessment and diagnosis of LBP in primary care recommends:

• diagnostic triage;

• history and physical examination to identify red flags;

• neurologic testing for radiculopathy;

• no routine imaging in the absence of concern for serious pathology; and

• assessment of yellow flags based on psychosocial factors.

Diagnostic triage of LBP targets red flag clinical findings that may indicate the presence of systemic illness (e.g. infection, cancer) or imminent neurologic compromise (e.g. spinal cord compression). Spinal cord or cauda equina compression are emergencies that arecharacterized by rapidly progressive neurologic deficits. Spinal cord compression can be caused by unstable spinal structure, herniation of intervertebral disc(s), trauma, malignant tumor, benign tumor, or infection (e.g. epidural abscess). Patients who present with LBP accompanied by evidence of infection, history of or suspicion for cancer, or rapidly progressive neurologic deficits require urgent neurologic, radiographic, and laboratory evaluation, which are most expeditiously available in a hospital/ED. Pain is usually the first symptom of spinal cord compression. However, motor weakness and sensory findings are present in most patients at diagnosis, and bilateral leg weakness may be elicited in multiple nerve root distributions (L3-S1). Bowel and bladder dysfunction are later findings.

Since early diagnosis and prompt treatment improves outcomes, PCPs must recognize the red flags for cauda equina syndrome that include perineal numbness, difficulty initiating urination or urinary retention, fecal incontinence, or hyporeflexia. Red flags for tumor, infection, or pathologic fracture include age over 50 years, fever, chills, recent urinary tract or skin infection, penetrating wounds near the spine, significant trauma, night pain or pain at rest, steroid or immunosuppressive therapy, substance abuse or intravenous drug use, unexplained weight loss, and progressive motor or sensory deficit.

Table 75.6 lists red flag findings for urgent evaluation delineated by potential cause.

Red flags require an immediate evaluation that includes X-rays, computed tomography (CT) scan or magnetic resonance imaging (MRI), laboratory studies, and urgent neurologic assessment. On the other hand available evidence shows that routine advanced imaging (CT or MRI) is not associated with enhanced patient outcomes in patients who do not present with red flags. Clinical practice guidelines are uniform in their recommendation that imaging or other diagnostic tests in patients with non-specific LBP should NOT be routinely performed. In general, radiographic studies can be delayed for one month, during which time 90% of patients will have reported improvement or resolution of the pain. ^,

PCPs should also be able to identify yellow flags that may be predictive of prolonged bouts of LBP and/or poor prognosis. These factors are psychosocial in nature and include affective, behavioral, belief, social, and occupational features. Besides the above, certain pain factors should cause concern, such as the severity of symptoms and impairment of functional capacity. Patients with these characteristics are at risk of developing persistent pain that is difficult to manage with routine care and may develop long term disability. Identification of these risk factors can guide the PCP in making appropriate referrals for psychological and/or social service support. These patients will require an interdisciplinary approach to achieve the best outcome.

Table 75.7 lists yellow flag issues in LBP.

Timing and Description of Low Back Pain

As with any pain complaint, how the patient experiences and describes LBP offers clues to its origin. Clinical communication should validate the complaint and encourage the patient to fully describe the onset and experience of the pain; body diagrams such as that found in the BPI are available in electronic health records, may be used to document the location, dermatomal distribution, and possible referred areas of pain.

PCPs must first establish whether the LBP had an acute versus a slow onset. Sudden, abrupt onset of pain is characteristic of muscle strain/sprain or herniated disc; patients typically are able to pinpoint the activity that caused the pain. Those with disc herniations may describe pain that is worse when sitting. In contrast, LBP with a slow, insidious onset suggests the presence of spondylolisthesis (slippage of one vertebral body on the adjacent one), osteoarthritis, or spinal stenosis. Spinal stenosis pain is aggravated by lumbar extension but improved by sitting or leaning forward (hence, the “handlebar” or “shopping cart” signs).