ABSTRACT: BACKGROUND:There is insufficient information about risk factors for COVID-19 diagnosis and adverse outcomes from low and middle-income countries (LMICs). OBJECTIVES:We estimated the association between patients' characteristics and COVID-19 diagnosis, hospitalisation and adverse outcome in Mexico. METHODS:This retrospective case series used a publicly available nation-level dataset released on May 31, 2020 by the Mexican Ministry of Health, with patients classified as suspected cases of viral respiratory disease. Patients with COVID-19 were laboratory-confirmed. Their profile was stratified by COVID-19 diagnosis or not. Differences among COVID-19 patients based on two separate clinical endpoints, hospitalisation and adverse outcome, were examined. Multivariate logistic regressions examined the associations between patient characteristics and hospitalisation and adverse outcome. RESULTS:Overall, 236?439 patients were included, with 89?756 (38.0%) being diagnosed with COVID-19. COVID-19 patients were disproportionately older, males and with increased prevalence of one or more comorbidities, particularly diabetes, obesity, and hypertension. Age, male gender, diabetes, obesity and having one or more comorbidities were independently associated with laboratory-confirmed COVID-19. Current smokers were 23% less likely to be diagnosed with COVID-19 compared to non-smokers. Of all COVID-19 patients, 34.8% were hospitalised and 13.0% experienced an adverse outcome. Male gender, older age, having one or more comorbidities, and chronic renal disease, diabetes, obesity, COPD, immunosuppression and hypertension were associated with hospitalisation and adverse outcome. Current smoking was not associated with adverse outcome. CONCLUSION:This largest ever case series of COVID-19 patients identified risk factors for COVID-19 diagnosis, hospitalisation and adverse outcome. The findings could provide insight for the priorities the need to be set, especially by LMICs, to tackle the pandemic.