Severity, mortality, long COVID-19, and quality of life: Insights from a cohort study of hospitalized COVID-19 patients during the delta variant predominance period in Thailand.

Background: The COVID-19 pandemic, declared in March 2020, has had significant global impacts, with Thailand reporting over 4.6 million cases and 32,000 fatalities by September 2022. Long COVID, or Post-COVID Conditions (PCC), affects 10-30% of COVID-19 patients globally, with symptoms lasting beyond three months. Common issues include fatigue, brain fog, respiratory problems, and psychological effects such as anxiety and depression. Symptoms can persist regardless of the initial infection severity, and ongoing research continues to refine understanding and management strategies. To address residual symptoms of COVID-19 during the Delta variant predominance period, a study was conducted from July to December 2021 at a tertiary care hospital in Chiang Mai, Thailand. The study aimed to describe the characteristics of COVID-19 patients, explore the Long COVID symptoms experienced by patients after discharge, and assess their quality of life.

Methods: The study characterized 604 are moderate to severe COVID-19 patients at Tertiary Care Hospital during the Delta wave in Thailand (July-December 2021), using secondary data from medical records. Confirmed cases were cohort monitored using a Long COVID questionnaire for symptoms, chronic conditions, and social impact a year after discharge. Quality of life was evaluated using the SF-12 questionnaire (SF-12: 12-Item Short Form Survey). Long COVID, in this study, is defined as the persistence or emergence of one or more physical, psychological, or cognitive symptoms that last for more than 12 weeks after the initial onset of COVID-19 and cannot be explained by alternative diagnoses. This includes, but is not limited to, symptoms such as fatigue, dyspnea, chest pain, cough, cognitive dysfunction ("brain fog"), insomnia, anxiety, or depression.

Findings: Most patients were Thai (85.9%) and female (57.3%), with obesity common among those aged 18-60 (48.3%). Severe cases and mortality were higher in patients over 60 (30.2%) and unvaccinated patients (60.4%). Severity was related with male gender, older age, lack of antiviral use, and being unvaccinated; overweight status, comorbidities, and abnormal chest x-rays were not significant. Deaths were influenced by gender, age, and antiviral use, but not hospital stay duration, overweight status, comorbidities, or vaccination status. At one-year follow-up, Long COVID symptoms were reported in a small proportion of patients (4.2% shortness of breath, 1.5% chronic cough), mostly in adults and older adults. Other symptoms were rare (<1%) and limited to the 18-60 age group. No severe neurological or systemic symptoms were reported. One-year post-hospitalization, 79.15% had no Long COVID symptoms. Quality of life scores were high (Physical Component Summary: PCS = 48.62, Mental Component Summary: MCS = 50.65).

Interpretation: This study found a very low prevalence of Long COVID symptoms, which may be due to the severity of the Delta variant leading to higher mortality among patients with severe illness. Those who survived and recovered mostly had moderate symptoms and were predominantly under 60 years of age, which may explain the lower occurrence of Long COVID in this group. The majority of COVID-19 patients in Chiang Mai experienced moderate symptoms and had a high survival rate. Despite varied long COVID symptoms, most reported good physical and mental health one year after recovery. These findings highlight the resilience of patients and the importance of monitoring long-term health outcomes.