Study design
This study is a descriptive correlational research with a cross-sectional design.
Population and sample size
The population comprised male and female patients aged 18 years and older with COVID-19 infection confirmed by an antigen test kit (ATK) or real-time polymerase chain reaction (RT-PCR) and who were examined at the outpatient departments of two tertiary hospitals in Bangkok, Thailand. Patients were selected on the basis of the following inclusion criteria: 1) Patients who had persistent abnormal symptoms or new symptoms for 28 days after infection up to the present day, and 2) patients who could read, write, and communicate in Thai. Exclusion criteria were 1) patients diagnosed by a doctor with psychiatric disorders, such as schizophrenia or depression; 2) patients who had concomitant diseases such as chronic heart failure, obstructive sleep apnea, chronic obstructive pulmonary disorder, and asthma; 3) patients with records of fatigue and insomnia before diagnosis with COVID-19; 4) patients who were pregnant; and 5) when the patient was aged 60 years and older, the patient was screened for dementia with the Mini-Cog instrument and found to have a score of less than three points. Data were collected from April to September 2023. Sample size was determined by analyzing the power of the test. An “r” score of 0.30 was obtained based on Muragod et al., who studied correlations between fatigue and psychological health-related quality of life among COVID-19 survivors.22 The sample size was calculated using the G*Power 3.1.9.7 program.23 The power of the test was set at 0.80, and statistical significance was set at 0.05. The correlation effect size was 0.0989 with four predictive variables. In this study, a sample size of 126 subjects was obtained.
Research Instruments
The instruments used in this study comprised the following two parts:
Part 1: Participant screening used the Mini-Cognitive Assessment Instrument developed by Borson et al.24 and translated into Thai by Trongsakul et al.25 The instrument used three questions to assess elderly subjects aged 60 years. Out of a score range of 0–5 points, scores of ≥3 points indicated no cognitive impairment, whereas scores of <3 points indicated possible cognitive impairment.
Part 2: Data collection instruments comprising:
1. The personal data and illness record questionnaire for patients with post-COVID condition was created with 26 questions divided into the following two parts: 1) personal data comprising gender, age, BMI, marital status, treatment rights, highest level of education, occupation, mean monthly income, height, marital status, treatment rights, highest level of education, occupation, mean monthly income, number of family members, cohabitants, record of chronic diseases, record of COVID-19 vaccinations, and number of COVID-19 vaccine doses received; and 2) illness records of patients with post-COVID conditions were data obtained from inquiries collected from medical records detailing the number of COVID-19 infections, COVID-19 detection method, the post-COVID period, quarantine or treatment facility, level of COVID-19 severity, symptoms while infected with COVID-19, and persistent or new symptoms after becoming infected with COVID-19 for ≥28 days after infection up to the present day.
2. Pittsburgh Sleep Quality Index (PSQI) developed by Buysse et al.26 was translated into Thai by Jirapramook and Tanchaisawad.27 The PSQI assesses sleep quality and disruption in the past month. The instrument had a score range of 0–21 points. Scores of ≤5 points indicated good sleep quality, whereas scores of >5 points indicated poor sleep quality. In this study, the instrument received a Cronbach’s alpha coefficient of 0.74.
3. The Functional Assessment of Chronic Illness Therapy-Fatigue Scale was used to assess fatigue and effects on activities of daily living in the past seven days. The scale had a score range of 0–52 points. Low scores indicated that patients had high fatigue or poor physical function, whereas high scores indicated low fatigue or good physical function.28 The scale received a Cronbach’s alpha coefficient of 0.89 in this study.
4. The revised Thai version of the multidimensional scale of perceived social support was developed by Zimet et al.29 and translated into Thai by Wongpakaran N and Wongpakaran T.30 The scale measures perceived social support from family, friends, and special persons and had a score range of 12–84 points. High scores meant high social support, whereas low scores meant low social support. The instrument received a Cronbach’s alpha coefficient of 0.80 in this study.
5. EuroQol Group-5 Dimension-5 (EQ-5D-5L) Levels was developed by EuroQol Group31 and translated into Thai by Pattanapesat et al.32 The questionnaire consisted of two parts. Part One comprised five areas of health: mobility, self-care, regular activities, pain/discomfort, and anxiety/depression. The questionnaire had a score range from −0.283 to 1. Zero points meant the worst health, and one point meant the perfect health; negative scores indicated that patients had conditions worse. Part Two was a direct health measurement with a visual analog scale (VAS), which had a value range of 0–100, where 0 points indicated the worst health, and 100 points indicated the best health. The instrument received a Cronbach’s alpha coefficient of 0.72 in this study.
Ethical Considerations
Herein, protections were considered for the participants’ rights in three areas: personal respect, beneficence, and justice. This study received approval for human research from the Institutional Review Board, Faculty of Nursing, and the Institutional Review Board, Faculty of Medicine, Siriraj Hospital, Mahidol University, which jointly considered and confirmed the research project in the form of an MOU, Project Code: MU-MOU CoA No. IRB-NS2023/741.2201, and the Institutional Review Board, Bangkok Metropolitan Administration, Project Code: U006hh/66_EXP. This study received approval before the research began.
Data Collection Methods
The researcher collected data herself. This cross-sectional research was conducted at two tertiary hospitals in Bangkok from April to September 2023 by presenting a letter to the administrators of both hospitals to request support for data collection from the Faculty of Graduate Studies, Mahidol University. After receiving permission for data collection, the researcher introduced herself, explained the details of the study, and collected data according to the procedure by spending 45–60 min to collect data. After obtaining 126 subjects, the researcher ended data collection and analyzed the data.
Data Analysis
Statistical data were analyzed using the SPSS program. The patients’ basic data were analyzed by using descriptive statistics in distributing values to determine frequency, percent, mean, and SD. Correlations were analyzed using Pearson’s product moment correlation coefficient. Predictive power was analyzed using linear multiple regression analysis using the enter method. Significance was set at 0.05.