Comprehensive analysis of long COVID in a Japanese nationwide prospective cohort study

Social impact of brain fog and analysis of risk factors: Long COVID in Japanese population

OBJECTIVE

To reveal the clinical features and assess risk factors linked to brain fog and its societal implications, including labor productivity, providing valuable insights for the future care of individuals who have experienced coronavirus disease 2019 (COVID-19).

METHODS

We analyzed a comprehensive cohort dataset comprising 1,009 patients with COVID-19 admitted to Japanese hospitals. To assess brain fog, we analyzed patients who responded to a questionnaire indicating symptoms such as memory impairment and poor concentration.

RESULTS

The prevalence of brain fog symptoms decreased 3 months posthospitalization but remained stable up to 12 months. Neurological symptoms such as taste and smell disorders and numbness at hospitalization correlated with a higher frequency of identifying brain fog as a long COVID manifestation. Our findings indicated that advanced age, female sex, a high body mass index, oxygen required during hospitalization, chronic obstructive pulmonary disease, asthma, and elevated C-reactive protein and elevated D-dimer levels were risk factors in patients exhibiting brain fog. Additionally, we demonstrated the negative impact of brain fog on labor productivity by presenteeism scores.

INTERPRETATIONS

This study clarified the clinical characteristics of patients experiencing brain fog as a long COVID manifestation, specifically emphasizing neurological symptoms during hospitalization and their correlation with brain fog. Additionally, the study identified associated risk factors for its onset and revealed that the emergence of brain fog was linked to a decline in labor productivity.

CT-derived vertebral bone mineral density is a useful biomarker to predict COVID-19 outcome

The low vertebral bone computed tomography (CT) Hounsfield unit values measured on CT scans reflect low bone mineral density (BMD) and are known as diagnostic indicators for osteoporosis. The potential prognostic significance of low BMD defined by vertebral bone CT values for the coronavirus disease 2019 (COVID-19) remains unclear. This study aimed to assess the impact of BMD on the clinical outcome in Japanese patients with COVID-19 and evaluate the association between BMD and critical outcomes, such as high-flow nasal cannula, non-invasive and invasive positive pressure ventilation, extracorporeal membrane oxygenation, or death. We examined the effects of COVID-19 severity on the change of BMD over time. This multicenter retrospective cohort study enrolled 1132 inpatients with COVID-19 from the Japan COVID-19 Task Force database between February 2020 and September 2022. The bone CT values of the 4th, 7th, and 10th thoracic vertebrae were measured from chest CT images. The average of these values was defined as BMD. Furthermore, a comparative analysis was conducted between the BMD on admission and its value 3 months later. The low BMD group had a higher proportion of critical outcomes than did the high BMD group. In a subanalysis stratifying patients by epidemic wave according to onset time, critical outcomes were higher in the low BMD group in the 1st-4th waves. Multivariable logistic analysis of previously reported factors associated with COVID-19 severity revealed that low BMD, chronic kidney disease, and diabetes were independently associated with critical outcomes. At 3 months post-infection, patients with oxygen demand during hospitalization showed markedly decreased BMD than did those on admission. Low BMD in patients with COVID-19 may help predict severe disease after the disease onset. BMD may decrease over time in patients with severe COVID-19, and the impact on sequelae symptoms should be investigated in the future.

Calcium channel blockers may reduce the development of long COVID in females

With the rising numbers of patients infected with severe acute respiratory syndrome coronavirus 2, long coronavirus disease 2019 (COVID-19)-a sequelae of COVID-19-has become a major problem. Different sexes and age groups develop different long COVID symptoms, and the risk factors for long COVID remain unclear. Therefore, we performed subgroup analyses of patients with COVID-19, classifying them into different groups. In this multicenter cohort study, using an original questionnaire, we examined patients (≥18 years old) diagnosed with COVID-19 from November 2020 to March 2022 and hospitalized at participating medical facilities. In total, 1066 patients were registered (361 female, 620 male). Hypertension was the most common comorbidity (n = 344; 32.5%). Females with hypertension were significantly less likely to develop long COVID symptoms than those without hypertension (odds ratio [OR] 0.51, 95% confidence interval [CI] 0.27-0.98; p = 0.043). In females, Ca channel blocker administration, rather than having hypertension, was significantly associated with reductions in the frequency of alopecia (OR 0.14, 95% CI 0.03-0.67, p = 0.015), memory impairment (OR 0.14, 95% CI 0.02-0.82, p = 0.029), sleeping disorders (OR 0.17, 95% CI 0.04-0.67, p = 0.012), tinnitus (OR 0.23, 95% CI 0.05-0.98, p = 0.047), sputum (OR 0.31, 95% CI 0.10-0.92, p = 0.035), and fever (OR 0.33, 95% CI 0.12-0.93, p = 0.036). Several long COVID symptoms, including alopecia, were significantly negatively associated with Ca channel-blocker administration in female patients with long COVID. Calcium channel blockers may reduce the development of long COVID in females.

Cluster analysis of long COVID in Japan and association of its trajectory of symptoms and quality of life

BACKGROUND

Multiple prolonged symptoms observed in patients who recovered from COVID-19 are defined as long COVID. Although diverse phenotypic combinations are possible, they remain unclear. This study aimed to perform a cluster analysis of long COVID in Japan and clarify the association between its characteristics and background factors and quality of life (QOL).

METHODS

This multicentre prospective cohort study collected various symptoms and QOL after COVID-19 from January 2020 to February 2021. This study included 935 patients aged ≥18 years with COVID-19 at 26 participating medical facilities. Hierarchical cluster analysis was performed using 24 long COVID symptom at 3 months after diagnosis.

RESULTS

Participants were divided into the following five clusters: numerous symptoms across multiple organs (cluster 1, n=54); no or minor symptoms (cluster 2, n=546); taste and olfactory disorders (cluster 3, n=76); fatigue, psychoneurotic symptoms and dyspnoea (low prevalence of cough and sputum) (cluster 4, n=207) and fatigue and dyspnoea (high prevalence of cough and sputum) (cluster 5, n=52). Cluster 1 included elderly patients with severe symptoms, while cluster 3 included young female with mild symptoms. No significant differences were observed in the comorbidities. Cluster 1 showed the most impaired QOL, followed by clusters 4 and 5; these changes as well as the composition of symptoms were observed over 1 year.

CONCLUSIONS

We identified patients with long COVID with diverse characteristics into five clusters. Future analysis of these different pathologies could result in individualised treatment of long COVID.

TRIAL REGISTRATION NUMBER

The study protocol is registered at UMIN clinical trials registry (UMIN000042299).

Upper Respiratory Symptoms as Long COVID: Insight from a Multicenter Cohort Study

Objective

This study aimed to investigate the clinical features of long COVID cases presenting with upper respiratory symptoms, a topic not yet fully elucidated.

Study Design

Prospective cohort study.

Setting

A multicenter study involving 26 medical facilities in Japan.

Methods

Inclusion criteria were patients aged ≥18 years old with a confirmed COVID-19 diagnosis via severe acute respiratory syndrome coronavirus 2 polymerase chain reaction or antigen testing, who were hospitalized at the participating medical facilities. Analyzing clinical information and patient-reported outcomes from 1009 patients were analyzed. The outcome measured the degree of initial symptoms for taste or olfactory disorders and assessed the likelihood of these symptoms persisting as long COVID, as well as the impact on quality of life if the upper respiratory symptoms persisted as long COVID.

Results

Patients with high albumin, low C-reactive protein, and low lactate dehydrogenase in laboratory tests tended to experience taste or olfactory disorders as part of long COVID. Those with severe initial symptoms had a higher risk of experiencing residual symptoms at 3 months, with an odds ratio of 2.933 (95% confidence interval [CI], 1.282-6.526) for taste disorders and 3.534 (95% CI, 1.382-9.009) for olfactory disorders. Presence of upper respiratory symptoms consistently resulted in lower quality of life scores.

Conclusion

The findings from this cohort study suggest that severe taste or olfactory disorders as early COVID-19 symptoms correlate with an increased likelihood of persistent symptoms in those disorders as long COVID.

Impairment of Social-Related Quality of Life in COVID-19 Pneumonia Survivors: A Prospective Longitudinal Study

The post-acute sequelae of SARS-CoV-2 (PASC) pose a threat to patients' health-related quality of life (HRQOL). Here, the impact of COVID-19 on HRQOL and the clinical factors associated with impaired HRQOL were examined. Discharged COVID-19 patients were assessed at 3 and 6 months after disease onset. The patients completed a medical examination and the SF-36 questionnaire at these two time points and underwent pulmonary function testing at 6 months after disease onset. All had undergone computed tomography (CT) imaging upon hospital admission. Of the 74 included patients, 38% reported respiratory symptoms at 3 months, and 26% reported respiratory symptoms at 6 months after disease onset. The aggregated SF-36 scores declined in the role/social component summary (RCS), a category related to social activity. Patients with lower RCS tended to have respiratory sequelae or a relatively lower forced vital capacity. The CT score that reflected the extent of COVID-19 pneumonia was inversely correlated with the RCS score (3 months, p = 0.0024; 6 months, p = 0.0464). A high CT score (≥10 points) predicted a low RCS score at 6 months (p = 0.013). This study highlights the impairment of RCS and its associations with respiratory sequelae. The study also emphasizes the importance of radiological findings in predicting long-term HRQOL outcomes after COVID-19.

Clinical features of Japanese patients with gastrointestinal long-COVID symptoms

Gastrointestinal (GI) long-COVID symptoms, including diarrhea and abdominal pain, have been reported in patients with long-COVID. However, the clinical features of patients with GI long-COVID symptoms remain unclear. We conducted a large-scale prospective cohort study focusing on the clinical characteristics of patients with GI long-COVID symptoms in Japan. Among 943 COVID-19 patients, 58 patients (6.2%) had GI long-COVID symptoms. The health-related quality of life (QOL) parameters (the Short Form-8 [SF-8] and Euro Quality of Life 5 Dimensions 5 level [EQ-5D-5L]) at 12 months after diagnosis in patients with GI long-COVID symptoms were significantly lower than in those without GI long-COVID symptoms (P < 0.0001). Moreover, patients with GI long-COVID symptoms had more varied long-COVID symptoms compared to patients without GI long-COVID symptoms.