Functional Somatic Disorder Doesn’t Explain Quality of Life in Long COVID

A diagnosis of functional somatic disorder (FSD) was not significantly associated with health-related quality of life (QOL) among patients seeking care for long COVID, according to a cross-sectional study published in PLOS One.¹

The study, conducted through the CASPer-COVID program at Hôtel-Dieu Hospital in Paris, France, followed 773 adult patients evaluated between October 2021 and October 2024 and found that QOL was similarly impaired whether or not patients received the FSD diagnosis.

Study Design and Population

The CASPer-COVID program is a multidisciplinary day-hospital evaluation service for patients referred by their general practitioners for persistent symptoms following COVID-19. Before entering the program, patients underwent a standardized symptom-driven medical workup, including laboratory testing, imaging, and functional tests as clinically indicated, followed by 3 consecutive 1-hour consultations with an internist or infectious disease specialist, a psychiatrist, and an adapted physical activity specialist.¹

Investigators used the 36-Item Short-Form Health Survey (SF-36) to generate a Physical Component Summary (PCS) and a Mental Component Summary (MCS), with higher scores from 0 to 100 indicating better QOL. Among the 773 patients analyzed (median age, 44 years; 64% women), QOL was markedly impaired, with a median PCS of 44 and median MCS of 39. A diagnosis of FSD was established in 76.5% of patients, based on a combination of cognitive and behavioral mechanisms consistent with FSD and the absence of medical findings that fully explained persistent symptoms.¹

No Significant Association With FSD Diagnosis

In multivariable linear regression models adjusting for age, gender, body mass index, comorbidities, hospitalization for acute COVID-19, core persistent symptoms, symptom duration, depressive and anxiety symptoms, and physical activity, a diagnosis of FSD was not significantly associated with either MCS (β, 1.11; 95% CI, −1.30 to 3.53) or PCS (β, −1.60; 95% CI, −3.88 to 0.67) scores.¹

Instead, lower PCS and MCS scores were associated with higher depressive and anxiety symptoms, lower physical activity levels, and pain. Lower PCS scores specifically were also associated with female gender, hospitalization for acute COVID-19, and longer symptom duration.¹

The authors noted that depressive and anxiety symptoms showed particularly large effect sizes for MCS and that pain was associated with the worst physical component scores, exceeding the minimum clinically important difference for the SF-36.¹

In a sensitivity analysis, the authors replaced the FSD diagnosis with the Somatic Symptom Disorder-12 (SSD-12) scale, a tool assessing the cognitive features of the DSM-5 somatic symptom disorder B criteria. This substitution did show a significant association with both mental and physical quality of life (β, −0.42; 95% CI, −0.56 to −0.29, and β, −0.56; 95% CI, −0.69 to −0.44, respectively).¹

The authors cautioned that this result should be interpreted carefully, as the SSD-12 captures symptom-related perceived impairment and may conceptually overlap with the QoL outcome itself, rather than representing a superior predictive construct compared with the clinical FSD diagnosis.¹

Reframing the FSD Diagnosis

The study authors emphasized that their findings do not support the assumption that patients diagnosed with FSD have better QOL than other patients with long COVID. They noted that FSD has been described in other clinical contexts as being associated with QOL impairments comparable to, or exceeding, those seen in well-defined medical conditions with similar symptoms.¹

"To conclude, in patients with long COVID seeking care in a tertiary care setting, a diagnosis of FSD by an experienced multidisciplinary team was not significantly associated with health-related QOL," the study authors wrote.¹ "Therefore, the diagnosis of FSD in this context should be acknowledged as the recognition of a severe condition."

The authors pointed out that the FSD diagnosis is frequently perceived as stigmatizing and may be misinterpreted by patients as a dismissal of their symptom burden, given that physicians and patients often diverge in their perceptions of long COVID's severity. Reframing the diagnosis as an acknowledgment of illness severity, rather than a minimization of it, could reduce this stigma and lower barriers to care that may benefit both conditions, including cognitive behavioral therapy approaches that have shown promise for long COVID.¹

Study Limitations

The authors acknowledged several limitations. The cross-sectional design prevents causal interpretation. For example, reduced physical activity could reflect avoidant behavior characteristic of FSD, a consequence of physical impairment, or both.¹

Because the sample was drawn from a tertiary care center with a long median symptom duration of about 1.6 years, referral bias may limit generalizability to patients with milder long COVID managed in primary care. Interrater agreement for the FSD diagnosis was not formally assessed, though participating psychiatrists received standardized training and held regular case discussion meetings to improve diagnostic harmonization.¹

Long COVID's Toll on Quality of Life and Work

The Paris findings add to a growing body of evidence documenting the substantial and often prolonged effect of long COVID on quality of life across different populations and measurement tools.

A UK cohort study using the validated EuroQol EQ-5D-5L questionnaire found that participants self-reporting long COVID had markedly higher odds of reporting loss of health-related quality of life compared with those who did not report long COVID (odds ratio, 4.7; 95% CI, 3.72-5.93). That study, part of the OpenPROMPT research platform, reported that EQ-5D utility scores among people with long COVID were lower than those reported for patients with heart failure, multiple sclerosis, and end-stage renal disease. Breathlessness and fatigue were identified as major contributors to reduced quality of life in that cohort.²

A cross-sectional survey of 348 health care workers in Portugal similarly found that long COVID was significantly associated with lower life satisfaction, as measured by the Satisfaction With Life Scale, in multivariate analysis (B, −1.35; SE, 0.68; P = .048). In that study, extreme fatigue and cognitive dysfunction were strongly and negatively associated with self-reported workplace performance, while long COVID itself was excluded from the multivariate performance model due to its strong association with those same symptoms.³

According to the CDC, about 1 in 5 adults with long COVID have reported experiencing significant limitations in their daily activity, and long COVID is a recognized condition that may qualify as a disability under the Americans with Disabilities Act. The CDC also notes that some estimates suggest more than 1 million US adults are out of work at any given time due to long COVID, with additional impacts including increased health care costs and financial hardship related to food and housing.⁴

What This Means for Pharmacists

Pharmacists are frequently a first point of contact for patients managing chronic, hard-to-treat symptoms, including fatigue, pain, and cognitive complaints associated with long COVID. The CASPer-COVID findings underscore that a diagnosis of FSD should not be read by clinicians, or communicated to patients, as evidence that their condition is less severe or less "real." Pharmacists counseling patients with long COVID can reinforce that persistent symptoms are recognized as clinically significant regardless of diagnostic label and can help identify patients who may benefit from referral for depressive or anxiety symptoms, pain management, or structured physical activity programs, all of which were independently associated with quality of life in the study.¹

Given the CDC's guidance that long COVID may qualify as a disability, pharmacists may also play a role in supporting medication management and adherence for patients navigating workplace accommodations or broader care coordination.⁴

REFERENCES

1. Gouraud C, Guemouni S, Thoreux P, et al. Health-related quality of life among patients with long COVID according to the presence of a diagnosis of functional somatic disorder: A cross-sectional study. PLoS One. 2026;21(8):e0354238. Published 2026 Aug 5. doi:10.1371/journal.pone.0354238

2. Carlile O, Briggs A, Henderson AD, et al. Impact of long COVID on health-related quality-of-life: an OpenSAFELY population cohort study using patient-reported outcome measures (OpenPROMPT). Lancet Reg Health Eur. 2024;40:100908. Published 2024 Apr 24. doi:10.1016/j.lanepe.2024.100908

3. Prazeres F, Romualdo AP, Campos Pinto I, Silva J, Oliveira AM. The impact of long COVID on quality of life and work performance among healthcare workers in Portugal. PeerJ. 2025;13:e19089. Published 2025 Mar 10. doi:10.7717/peerj.19089

4. Centers for Disease Control and Prevention. Living With Long COVID. CDC. Updated March 9, 2026. Accessed August 6, 2026. https://www.cdc.gov/long-covid/living-with/index.html