Long COVID, also termed post-COVID syndrome or post-acute sequelae of SARS-CoV-2 (PASC), has become a major health concern. It is estimated that 7 million Americans may be suffering from long COVID. The National Institutes of Health (NIH) has earmarked more than $1 billion for research and management of long COVID, and multispecialty clinics to evaluate and treat individuals with post-recovery symptoms have been set up in almost every state.

These clinics may serve as a model for improved therapy of many chronic, poorly understood illnesses, including chronic pain.

This article will explore the potential that long COVID clinics may provide new chronic illness models that:

  • establish better disease diagnostic classification
  • include greater primary care involvement
  • are based on an integrated multidisciplinary clinic structure
  • promote patient-centric, biopsychosocial approaches to care

Long COVID and Chronic Pain: A Better Diagnostic Classification

To date, there is no universally accepted definition or diagnostic criteria for long COVID or for chronic pain. The diagnosis of long COVID is considered in individuals who have medical symptoms following SARS-CoV-2 infection that persist and cannot be explained by another medical condition. However, there has been no consensus regarding what these medical “symptoms” consist of, what constitutes “persistence,” and how to define “another” medical condition.

In any medical condition defined by symptoms, it is important to control for the presence of similar symptoms in the general population. Most reports of long COVID have not utilized such population controls. The methodology of these studies has also varied, with many involving community-based longitudinal surveys and a smaller number of studies relying upon medical electronic health records (EHRs). While longitudinal studies have the advantage of assessing patients’ lived experience and can survey pre-pandemic health symptoms, such data seldom control for symptoms in the general population and are subject to individual patient recall bias. EHR-based studies, on the other hand, accurately compare symptoms in patients to those of matched controls but only survey patients with a medical diagnosis of long COVID or similar diagnoses in the record.

Because of this lack of uniform diagnostic criteria, the estimates of long COVID prevalence have varied dramatically, from 2% to 10% to 30% to 50% of SARS-CoV-2 infected patients. Our own more stringent long COVID definition is similar to recent international definitions and includes patients with at least 3 of the more characteristic symptoms that have been present for at least 2 to 3 months and that can’t be explained by a known medical disorder.

In fact, only in the past 10 to 15 years has chronic pain been recognized “as a disease in itself.”³ It was not until 2019 that the International Classification of Diseases (ICD) established a diagnostic coding system for chronic pain and changed the chronic pain classification to reflect the importance of distinguishing subsets of chronic pain patients, such as those with associated cancer, neurologic conditions, or with structural damage.

Steps to Improve Definitions/Classification Criteria for Long COVID and Chronic Pain

  • Symptoms should be compared to those in general population
  • Include longitudinal patient surveys and medical records
  • Define the minimum duration of symptoms
  • Determine the requisite symptom severity
  • Distinguish patients with any other medical condition
    • Is there organ damage?
    • Recognize different disease phenotypes

Most long COVID clinics in the US do not involve primary care physicians (PCPs). Similarly, chronic pain clinics in the US are generally not integrated with primary care practices. Yet, in the US, PCPs often feel overwhelmed when trying to manage long COVID (as well as chronic pain). As noted, long COVID can present with multiple symptoms (some subjective, and without physical or laboratory evidence) and involve many internal body systems. Add to this the fact that there is no clear guidance regarding testing or referral pathways for the condition.

In the United Kingdom, primary care teams are very much involved in COVID care, largely because 90% of all UK National Health Service (NHS) contacts take place within primary care. Thus, their long COVID clinics were easily integrated into the country’s NHS.⁵ Primary care teams normally include general practitioners, advanced clinical practitioners, healthcare assistants, clinical pharmacists, and physical therapists, all of whom share electronic and clinic records. In the UK, guidelines for chronic pain management have been regularly updated by the National Institute for Health and Care Excellence (NICE).²

Long COVID Multidisciplinary Clinic Protocols

The first long COVID clinics in the US, also termed COVID-19 Recovery Clinics, opened in May and June of 2020 at major medical centers in New York. Initially, these clinics were established to facilitate the recovery of hospitalized individuals with COVID-19 infection and help them transition back home. However, as the persistent symptoms of long COVID became better recognized and characterized, the role of these clinics evolved, and they have become central figures in the diagnosis and treatment of long COVID.⁶

Structure of Long COVID Clinics in the US

Currently long COVID clinics in the US tend to follow this structure:

  • Initial Triage
    • Non-physician or PCP
    • Often virtual
    • Use standardized assessment
  • Specialty evaluation of symptoms and potential organ damage
    • Patient management
  • Integrated multidisciplinary team care
    • Patient-centric
    • Individualized rehabilitation
    • Common outcome measures, such as the Yorkshire Rehabilitation Scale
    • Ongoing education and evaluation
    • Share information to develop best practice guidelines

Triage and Initial Evaluation

Most long COVID clinic teams in the US begin their patient assessment with a virtual or in-person triage to determine if the patient meets criteria for a clinic appointment. Currently, there are no adequate guidelines on when to refer patients to long COVID clinics. Many clinics require that patients’ symptoms have persisted for more than 3 months. This seems reasonable since many patients improve between 1 and 3 months. In most instances, patient referral has been determined more by treatment concerns than by diagnostic concerns.

Many long COVID clinics initially triage patients virtually, utilizing a standardized symptom evaluation protocol.⁷ (These standardized questions include a complete history with a detailed symptom description. Specific neuropsychiatric screening questions should include symptoms of depression, anxiety, PTSD, sleep disturbance, cognitive disturbance, and neuropathy.⁶⁻⁸

Pain questions should consider descriptions and severity of muscle pain, joint pain, headache, and widespread pain, such as the fibromyalgia widespread pain index (WPI) instrument. Evaluation of patient activity and function should include questions regarding exercise, mobility, and work; questions regarding mood should include coping, fear, helplessness, hopelessness, stigma and isolation, family, and friends. Standardized quality of life surveys should include self-care, independence, need for medical care, hospitalization, and financial impact.

Once the initial triage evaluation is complete patients are referred to one or more specialists, based on current symptoms. Often, these can be broadly subdivided into cardiopulmonary or neurocognitive symptoms. The primary goal of this initial specialty evaluation is to assess the role of potential organ damage. For example, a pulmonologist may order pulmonary function tests or repeat a lung scan, a cardiologist may order an echocardiogram or cardiac imaging and a neurologist ask for a brain MRI or neuropsychological tests. These tests will guide further work-up and treatment.

Long COVID clinics, particularly those affiliated with medical centers, employ a variety of physician and allied healthcare professionals. Most clinics utilize multidisciplinary teams, and at medical centers in the US, these clinics most often have been under the auspices of a physical and medicine (PM&R) department. The clinics have included pulmonary/respiratory specialists (involved in 100% of clinics surveyed),⁸ cardiovascular specialists (92%), psychiatry and psychology (83%), physical therapy (83%), occupational therapy (75%), social work (75%), neurology (75%), primary care physicians (58%), nutrition (58%), and speech and language therapists (50%).⁸

Despite the controversy regarding exercise recommendations in long COVID, most long COVID clinics do initiate a cautious structured and supervised exercise program. This is done in increments, starting with walking, breathing exercises, gentle stretching, and light muscle strengthening. Treatment should include self-management strategies to improve the person’s functioning and quality of life.

Integrating Patient Care and Research

In any poorly understood, chronic illness without defined disease markers, patient experience is especially crucial to understanding and treating the condition. As discussed throughout this series on long COVID and chronic pain, ongoing research efforts in the US, such as the $1 billion earmarked for the RECOVER study, have included patient experience and expertise. Many of the RECOVER investigators are also participating in long COVID clinics in the US.

Many of the US and UK long COVID clinics were designed to rely heavily on patients’ lived experience. Outcome measures have focused on validated patient-reported measures, which have been surveyed in the clinic as well as in the patients’ home or workplace. One such outcome measure, the COVID-19 Yorkshire Rehabilitation Scale, would be appropriate to use in chronic pain settings.¹⁰ This is a 23-item questionnaire that patients complete on a smartphone app, grading symptom severity, functional limitations, and overall health.

The long COVID clinics in the US and UK have shared their initial experience, informally in the US and as part of government funding in the UK.¹¹ With built-in mechanisms to regularly collaborate, it is anticipated that such efforts will eventually produce a best-practice protocol.

As noted, long COVID and chronic pain do not fit classic biomedical disease models. Pathophysiology is not well understood. Organ damage does not necessarily correlate with symptoms or prognosis. Laboratory tests and imaging may be unremarkable. Patients may sense skepticism and feel stigmatized. A biopsychosocial model should be encouraged.

Both clinicians and patients must recognize the bidirectional mind-body interaction that governs chronic illness. Medications may be utilized, but there is no strong evidence that they are effective in these complex conditions. It is important, therefore, to evaluate the efficacy and adverse impact of medications, particularly with RCTs. Until more is known, medications should be used in conjunction with an activity and exercise program and psychological therapy, such as cognitive behavioral therapy to provide a biopsychosocial approach to care.

Practical Takeaways

Clinicians treating long COVID and chronic pain struggle with similar concerns, such as do these conditions represent a specific disease state, how can they be best diagnosed, what is the role of primary and specialty care, and how can care be best organized?

Finally, society at large must recognize the enormous economic and quality of life burden stemming from these chronic conditions and push ahead a research and treatment plan that is long overdue.