In this review: A comparison of pain, fatigue, and function between post-COVID 19 condition, fibromyalgia, and chronic fatigue syndrome: a survey study (Pain; abstract only available for free)  

The Message

Researchers and providers have noted that many of the symptoms of long COVID can be similar to two other conditions — fibromyalgia, or FMS, and chronic fatigue syndrome, or CFS. But how does symptom severity and impact on function compare among the conditions both individually and in combination? New survey-based research is beginning to answer those questions, with initial findings indicating that, generally, individuals with long COVID experience symptom phenotypes similar to those with FMS and CFS when it comes to cognitive and physical function. One difference is that those with long COVID tend to report slightly less pain, fatigue, and functional limitations overall. Survey results also indicated that combinations of the three conditions are associated with increased severity in nearly all symptom domains studied. Authors of the study hope that taking a deeper dive into these symptom profiles will help address "the need for a comprehensive approach" to the management of long COVID.

The Study

Researchers analyzed data from a battery of surveys administered to individuals between 18 and 80 years old diagnosed with long COVID (authors of the study use the term "post-COVID-19"), FMS, or CMS, as well as any combination of the three. Surveys used included the Brief Pain Inventory, the Fatigue Severity Scale, the Multisensory Amplification Scale, the Multidimensional Inventory of Subjective Cognitive Impairment, and symptom impact components of the Patient-Reported Outcomes Information Systems Bank (aka PROMISE Bank) addressing fatigue, sleep disorder, dyspnea, pain interference, and physical function. Psychological assessments included the catastrophizing section from the Coping Strategies Questionnaire, the Tampa Scale of Kinesiophobia-11, the Hospital Anxiety and Depression Scale, and the Patient Health Questionnaire-2.

APTA members Adam Janowski, PT; Joseph Lesnak, PT, DPT; Dana Dailey, PT, PhD; Ruth Chimenti, PT, PhD; Kathleen Anne Sluka, PT, PhD, FAPTA; and Giovanni Berardi, PT, PhD, were among the co-authors of the study.

Participants 

A total of 707 complete survey records were included in the study — 294 from men and 413 from women. Of those who reported experiencing only one condition, 203 had long COVID, 99 had FMS, and 87 had CFS. Among the 318 respondents who reported multiple conditions, 22 identified as having long COVID and FMS, 40 identified as having long COVID and CFS, 109 reported FMS and CFS, and 147 had all three conditions. Respondents were mostly white, ranging from 66.1% (CFS and FMS) to 81.8% (long COVID and FMS) in each individual condition and condition combination group.

Findings

• The long COVID cohort reported levels of moderate-to-severe fatigue and pain at rates greater than the standard deviation for the general population, as well as comparatively lower cognitive and physical function. They didn't report notably different rates of multisensory sensitivity, sleep disturbance, or dyspnea with activity.
• Compared with the diagnostic groups studied, pain and pain interference levels of the long COVID group were lower than those with FMS or multiple diagnoses — but the differences did not reach statistical significance, "suggesting that pain in post-COVD-19 is similar to those with FMS and CFS," authors write.
• While higher than the general population, the long COVID group's fatigue intensity averages were lower than the CFS group and the CFS and FMS group. Fatigue impact on daily activities was similar across all the groups.
• All groups reported lower cognitive function compared with the general population, but the long COVID group tended to register the lowest scores.
• The long COVID group reported lower rates of impairment compared with the FMS and multi-diagnosis groups.

Why It Matters

Long COVID is estimated to affect as much as 30% of those who contracted COVID-19, posing a significant — and relatively new — health care burden. Research has focused on identifying the symptoms associated with the condition, and comparisons between CFS and FMS have been made, given the multisystem effects of all three conditions. What's been missing, authors argue, is a clearer picture of just how those symptoms stack up across the conditions. Getting a more detailed picture of those differences "may help identify disease severity, direct treatment allocation, and improve treatment efficacy," authors write.

Authors also note that their study is "a first pass to gain information to direct future studies," and that future studies "should assess if treatment responses vary and differences in pathophysiology exist among the identified symptom clusters."

More From the Study

Authors point out that unlike previous research, their analysis found that individuals with long COVD did not report higher levels of dyspnea compared with the general population. They believe the difference may have something to do with the populations studied: Earlier reports tended to be based on clinical examination of older participants at more acute stages of the condition, while their study was based on patient surveys that tended to capture a younger cohort, with an average age of 35.

Keep in Mind …

Authors acknowledge that their research didn't address every symptom reported by those with long COVID or the "underlying mechanisms" behind the symptoms. Limitations listed by the authors include the use of self-reported data, a lack of sociodemographic information, and absence of prior treatment information among respondents.

Get a handle on rehab's role in treating long COVID through the APTA Learning Center's "Long COVID Rehabilitation – Multidisciplinary Care: Pitfalls to Avoid and Pearls to Enhance Treatment."