Abstract: ASSESSEMENT OF OUTCOMES FOLLOWING IMPLEMENTATION OF ANTIVIRAL TREATMENT GUIDELINES FOR COVID-19 DURING THE FIRST WAVE IN THAILAND 1 2 3 4 Narumol Sawanpanyalert , Rujipas Sirijatuphat , Piamlarp Sangsayunh , Opass Putcharoen , 5 6 7 Weerawat Manosuthi , Poj Intalapaporn , Nattawan Palavutitotai , 8 9 2 Worawan Samritmanoporn , Nattapong Jitrungruengnij , Alan Maleesatharn 2,10 and Kulkanya Chokephaibulkit 1 Medical Emergency Response Unit, Department of Medical Services, Ministry of 2 Public Health, Nonthaburi Province; Faculty of Medicine Siriraj Hospital, 3 Mahidol University, Bangkok; Central Chest Institute of Thailand, Nonthaburi Province; 4 Thai Red Cross Emerging Infectious Diseases Clinical Center, Chulalongkorn University, 5 Bangkok; Bamrasnaradura Infectious Diseases Institute, Nonthaburi Province; 6 7 Division of Infectious Disease, Rajavithi Hospital, Bangkok; Lerdsin Hospital, Bangkok; 8 9 Nopparat Rajathanee Hospital, Bangkok; Department of Pediatrics, 10 Charoenkrung Pracharak Hospital, Bangkok; Siriraj Institute of Clinical Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand Abstract. Thailand encountered its first coronavirus disease 2019 (COVID-19) outbreak in March 2020 and the Thailand Ministry of Public Health rapidly developed COVID-19 treatment guidelines. In this study we aimed to describe the outcomes among patients treated following those initial guidelines and determine factors significantly associated with poor outcomes in order to inform efforts to improve COVID-19 treatment guidelines for Thailand. Nine hospitals in Bangkok submitted data from their COVID-19 patients using standardized case record forms. A poor outcome was defined as death, ICU admission, requiring intubation or requiring high-flow oxygen. Factors associated with these outcomes were assessed. A total of 744 patients (48.8% male) were included in the study. The median (interquartile range) age of study subjects was 37 (27-48) years; 8.4% were aged >60 years, 5.6% of subjects were obese and 16.5% had underlying conditions: obesity, immunocompromised status, diabetes, chronic conditions of lungs, kidneys, liver, cardiovascular or cerebrovascular systems or had an absolute lymphocyte 3 count <1,000 cells/mm . Among symptomatic patients, factors significantly independently associated with a poor outcome were: age >60 years (adjusted odds ratio (aOR): 2.50, 95% confidence interval (CI): 1.17-5.36, p = 0.018), having an underlying risk condition (aOR: 2.36, 95%CI: 1.27-4.39, p = 0.007), presenting with pneumonia (aOR: 6.60, 95%CI: 3.48-12.49, 572 Vol 52 No.4 July 2021 RISK OF SEVERE COVID-19 AND OUTCOMES OF ANTIVIRAL TREATMENT p <0.001) and azithromycin use (aOR: 2.36, 95%CI: 1.30-4.31, p = 0.005). Among symptomatic patients, the factor significantly associated with lower odds of having a poor outcome was hospital admission within 4 days of symptom onset (aOR: 0.44, 95%CI: 0.24-0.82, p = 0.009). Subgroup analysis revealed hospital admission within 4 days of symptom onset was significantly associated with a lower risk of a poor outcome only among patients who received treatment that included favipiravir (crude odds ratio (cOR): 0.320, 95%CI: 0.152-0.662, p = 0.003), but not among those who received a ritonavir boosted protease inhibitor (lopinavir or darunavir) or hydroxychloroquine (or chloroquine) without favipiravir (cOR: 0.58, 95%CI: 0.18-1.91, p = 0.372). In summary, the factors significantly..