Introduction

Almost everyone is aware of the presence of coronavirus 2019 (COVID-19) illness, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Classifying COVID-19 as an occupational illness is controversial, with several US states passing legislation granting the rebuttable presumption of causation by workplace exposure to some occupations (healthcare workers, first responders, etc). This area of law is changing rapidly, and physicians will have to check the current status of such law in the applicable jurisdiction to a case before them.

Administrative requests for impairment ratings before literature is published on the long-term outcomes in COVID-19 survivors will be seen in the near future. Because many journals use a two-year outcome assessment as a criterion for “long-term” outcomes, the information in this article should be considered as “interim advice.”

Individuals who claim to have had COVID-19 but who tested negative for the virus by polymerase chain reaction (PCR), and individuals who state they were ill and were not permitted to be tested, will likely have to have the causation question formally adjudicated before physicians are asked to assess for maximal medical improvement (MMI) and permanent physical impairment (PPI).

For those cases either accepted by a workers' compensation insurer or administratively adjudicated as work compensable, these questions will need to be answered: When is the person at MMI? How should PPI be rated? We offer several clinical scenarios to consider for administratively accepted cases for which an MMI date and PPI rating are requested.

Clinical Scenarios

Scenario 1: Individuals who are tested when asymptomatic only because they are known contacts of a person who tested positive. An example would be a healthcare worker in a hospital or nursing home with known cases who is tested despite the absence of any symptoms. If this individual remains asymptomatic but did test positive on PCR for having the live virus, there are no known long-term complications in those with subclinical infection. These individuals can be considered to be at MMI a few weeks after the positive test, and there is no permanent impairment.

Scenario 2: For those who are pre-symptomatic, ie, have not yet become symptomatic at the time of testing but do later become symptomatic, the average onset of illness is about 2 to 5 days later.^{1, 2} These individuals would be rated similar to the following scenarios 3 and 4.

Scenario 3: Individuals who test positive and who have mild disease. They are not hospitalized, and they recover at home, never having been significantly dyspneic. Once recovered, they are asymptomatic. When they can return to normal activity without symptoms, they can be declared to be at MMI and with no PPI (0%). There are currently no case reports of individuals with mild disease, who recover at home, and yet who have persisting symptoms suggesting permanent consequences. If necessary, to support this opinion, symptom validity can be verified by stress echocardiography (eg, stress echocardiogram) and pulmonary function testing (PFT) (eg, spirometry).

Scenario 4: Individuals who have moderate disease, ie, test positive, hospitalized, and treated with supplemental oxygen but are not placed in the intensive care unit (ICU) or on a ventilator. They usually have abnormal chest computed tomography (CT) scans and may have abnormal chest X rays. Some are more seriously ill and required an ICU stay, or were placed on a ventilator, or both. In these cases, review of hospital records is required to objectively document the organ systems with objective pathology.

The most common concern in these cases will be residual pulmonary or cardiac pathology either from the virus or from the ventilator. There may also be cases in which significant pulmonary involvement was documented by outpatient or emergency room imaging, and the person convalesced at home. Psychological illness may also be present, which is discussed later in the article.

History

If these individuals have persisting complaints of dyspnea on exertion or fatigue, the first assessment should be face-to-face in an office setting (not via telemedicine). Using release-of-information forms to obtain records from the primary care physician before the onset of COVID-19 and from healthcare providers and hospitals related to the treatment of COVID-19 will provide objective evidence of illness and help with questions about pre-existing status. Records should include evidence of a positive PCR test for the presence of the virus. Chest X ray or chest CT scan results would confirm pulmonary involvement occurred, as would physician-measured oxygen saturation below 95%.

Physical Examination

The physical examination should include traditional pulmonary and cardiac assessments and pulse oximetry. An additional and simple in-office screening test is the 6-minute walk test while the patient is wearing a pulse oximeter. Norms for distance walked by age are available,³ but the most important information would be change in pulse from sitting to walking, and whether desaturation (oxygen level on pulse oximeter) occurs during walking. Tachycardia (pulse >100) and less than normal distance walked with preserved oxygen saturation would suggest deconditioning and not permanent impairment.

Guidelines

The American College of Occupational and Environmental Medicine (ACOEM) guidelines on COVID-19 (April 24, 2020 update)⁴ contains a section on disability and return to work. They state that based on prior experience with other similar viral illnesses, patients who recovered without hospitalization will generally be adequately recovered from post-infection fatigue and ready to return to work after 2 to 3 weeks. This is about the time when some patients may be retested to see if they are still shedding the virus. The clinical significance of a recovered patient still having viral shedding is unclear and may not be a barrier to returning to work. For patients with documented pneumonia or who required supplemental oxygen therapy, recovery would be estimated to be 4 to 8 weeks after hospitalization or clinical recovery.

For patients who required mechanical ventilation for an acute respiratory distress syndrome (ARDS) illness, past experience has been that 50% of survivors may not have returned to work by 1 year from hospital discharge.^5-9 They also point out that on spirometry, lung volumes show about a 20% reduction that frequently resolves in 6 months. Thus, it would be logical to wait until hospitalized survivors are 6 months from discharge before evaluating for MMI and PPI.

Laboratory Testing

Blood testing for complete blood count and comprehensive metabolic panel should be obtained unless results from prior convalescent testing are available and normal.

If residual pulmonary impairment is plausible, then full spirometry (including measurement of diffusion capacity of carbon monoxide [DLCO], impedance testing, or nitrogen washout) should be obtained. The test results should be evaluated to verify that they meet the American Thoracic Society (ATS) criteria for full effort and reliability.^10-12

Pulmonary impairment can be rated using Table 5-4, Criteria for Rating Permanent Impairment due to Pulmonary Dysfunction (6th ed, 88), in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). In jurisdictions using the Fifth Edition of the AMA Guides, ratings come from Table 5-12, Impairment Classification for Respiratory Disorders, Using Pulmonary Function and Exercise Test Results (5th ed, 107). Many of the Sixth Edition internal medicine chapters have a footnote in the relevant table that identifies the “key factor” to be used for class assignment. Although Table 5-4 does not have such a footnote, on page 87 it indicates, “The examiner should note that throughout this chapter the objective test results are used as the primary or “key factor'.”¹³ To be class 0, each of the spirometry results for which tests are available must be normal, as defined by the numbers in the table. For class 1 to class 4 impairment, the worst of the tests determines class placement. Thus, if the DLCO results in a higher-class assignment than the forced vital capacity (FVC) or the forced expiratory volume in 1 second (FEV₁), the class would be determined by the DLCO result. ACOEM points out that lung diffusion abnormalities, if present, may take 5 years to resolve after ARDS. On spirometry, the DLCO is the test that best reflects diffusion abnormalities. There are no published studies of spirometry results in COVID-19 survivors, but the pathophysiology so far appears to be predominantly diffuse alveolar damage, hyaline membranes, and micro-angiopathic processes.¹⁴ The DLCO may be the most impaired pulmonary function on spirometry.

Cardiovascular injuries that are seen in ARDS and could occur in COVID-19 include the following conditions in Table 1.

Desaturation during exercise with normal spirometry would suggest impaired cardiac output (left ventricle ejection fraction [LVEF] by echocardiogram) or interstitial lung disease for which full metabolic stress echocardio-gram would be needed. If the echocardiogram is normal, then other systemic illness such as anemia or lung abnormalities are most likely. If the spirometry was normal, but stress testing showed the individual crossed the aerobic threshold (first ventilatory threshold on cardiopulmonary stress exercise testing [CPX]¹⁵ or metabolic stress echocardiogram) and the subsequent maximum oxygen (VO₂ max) consumption was abnormal, the VO₂ max measurement mentioned in either edition of the AMA Guides can be used for class assignment (6th ed, Table 5-4; 5th ed, Table 5-12). The formal interpretation for the test may provide evidence as to the pathophysiology of the individual (lung diffusion abnormality, pulmonary hypertension, reduced cardiac output, deconditioning or lack of effort on testing, etc).

COVID-19 patients can have cardiac complications. Some COVID-19 patients have ST-segment elevation on electrocardiogram (EKG) and have corresponding clots in major epicardial coronary arteries from the hypercoagulable state many of these patients experience.¹⁶ These patients can be rated as any other myocardial infarction patient. Some have viral myocarditis without large artery induced infarcts.¹⁷ These patients can be rated as any other cardiomyopathy patient. LVEF by echocardiogram or cardiac catheterization), brain natriuretic peptide (BNP) level, METs of exertion achieved on a treadmill test, or VO₂ max on CPX or metabolic stress echocardiogram (if performed) are the test results discussed in the Sixth Edition that are used as key factors to assign a class.

Pulmonary emboli may occur due to a hypercoagulable state¹⁸ or prolonged inactivity.¹⁹ Impairment would be evaluated by spirometry (infarction-reduced FVC) and by echocardiogram or metabolic stress echocardiogram showing pulmonary hypertension.

There are patients having large-vessel strokes, presumably due to the hypercoagulable state known to occur in some patients with COVID-19.²⁰ These would be rated like any other large-vessel stroke, and if cranial nerve or visual impairment were present, they would be rated according to Chapters 11 and 12 in either AMA Guides edition. Some severely ill patients with COVID-19–related ARDS have neurologic deficits while in the ICU, and some still have mental status alteration in short-term follow up.²¹ The AMA Guides point out that the more subtle the persisting mental status deficit is, the more likely formal neuropsychological testing is to formally verify and document the deficit (6th ed, Section 13.3d, 330; 5th ed, Section 13.3d, 319).

An unusual symptom being reported in some individuals with COVID-19 is anosmia, or the loss of sense of smell. It is not clear from early reports whether this is just the loss of sense of smell, or whether there is also loss of taste. Most of our sense of what food tastes like is determined by our sense of smell. Subjective loss of the sense of smell is not always validated on testing. Loss of the sense of smell from upper respiratory tract infections (URTIs) is known to recover in 32% to 66% of cases,²² so olfaction should be tested with the University of Pennsylvania smell identification test (UPSIT) or the Burghart Sniffin' Sticks.

Guillain-Barré syndrome and its variants have been reported during and just after COVID-19 illness,^{23, 24} and these are ratable using the chapter on the central and peripheral nervous system in both the Fifth and Sixth Editions of the AMA Guides. This diagnosis should not be used for subjective complaints of weakness and fatigue with no objective documentation of Guillain-Barré actually been present, by accepted criteria.²⁵ The residual respiratory and limb consequences of objectively documented disease are ratable.

Note that the central and peripheral nervous system chapter also has a rating methodology for myopathy²⁶ or for generalized peripheral neuropathy (Section 13-9 in either edition) that could be used in cases of these problems after objective documentation with electrodiagnostic tests and/or muscle ultrasound or magnetic resonance imaging (MRI) during the acute illness.^{27, 28}

While COVID-19 patients may have a hypercoagulable state (elevated D-dimer, etc) there are no current reports of persistent hypercoagulable state after recovery. Individuals with a persisting or permanent hypercoagulable state (6th ed, Table 9-12; 5th ed, Table 9-4) may be rated, but this will probably not be used in COVID-19 survivors. If thrombosis of a vessel(s) resulted in extremity complications, these would be rated using the extremity chapters. Similarly, if thrombosis in abdominal vessels occurred, it would be rated from the gastrointestinal (GI) or genitourinary (GU) chapter(s).

Acute hepatic injury and acute kidney injury, when they occur in patients with COVID-19, are usually markers of impending death, and survival with impairments in these organs is not common.²⁹ If an individual did survive these complications, they are ratable from the GI and GU chapters, like any other liver or kidney disease patient.

Providing care to COVID-19 patients can be stressful;^{30, 31} some individuals may present with post-traumatic stress disorder (PTSD) symptoms. Some had actual COVID-19, some were first responders or healthcare workers who witnessed first-hand illness or deaths,^32-34 and some had both of these experiences. Several states have created a legal presumption (sometimes rebuttable) that PTSD in these situations is presumed to have been caused by COVID-19.

The mental and behavioral disorders chapter uses the now antiquated Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR) criteria for PTSD diagnosis, and most mental health professionals are now using the more liberal diagnostic criteria in DSM-V. If the diagnosis is administratively accepted, and the MMI and PPI questions are asked, there are some caveats. Chapter 14 in either edition of the AMA Guides is largely silent about how MMI and permanency are to be objectively established in mental disorders. Modern systematic reviews indicate cognitive behavioral therapy (CBT) has better outcomes compared to medications^35-37 and, therefore, 12 to 18 sessions of CBT should logically have occurred before MMI is established. A further consideration is the stability of employment. If the individual is still in a “temporary” off-work status, the outcome of PTSD with a change in employment is not known. Thus, if a healthcare worker is still unwilling to return to work after CBT, an alternate career choice may need to be made, and PPI should logically be assessed after re-employment.

For jurisdictions that apportion, the mental and behavioral disorders chapter recommends that the rating be performed twice, once using three assessment tools based on symptoms and function before the inciting workplace exposure, and then using the same tools to describe the current symptoms and function. Subtracting the pre-existing impairment from the current impairment yields the impairment because of the current mental disorder of interest.

Conclusion

The information provided in this article is preliminary advice for those who are asked to rate permanent consequences of COVID-19 illness in those administratively accepted or adjudicated cases. With further clinical experience, the approach to rating may need to be modified slightly. However, the suggestions outlined should remain applicable for most of the foreseeable future.