Prevalence and factors associated with one-year mortality of infectious diseases among elderly emergency department patients in a middle-income country

BACKGROUND: This study aimed to determine the prevalence of infectious diseases and risk factors for one-year mortality in elderly emergency department (ED) patients. METHODS: A retrospective cohort study of patients aged 65 and over who visited the ED of one urban teaching hospital in Bangkok, Thailand and who were diagnosed with infectious diseases between 1 January 2016 and 30 June 2016. RESULTS: There were 463 elderly patients who visited ED with infectious diseases, accounting for 14.5% (463/3,196) of all elderly patients’ visits. The most common diseases diagnosed by emergency physicians (EPs) were pneumonia [151 (32.6%) patients] followed by pyelonephritis [107 (23.1%) patients] and intestinal infection [53 (11.4%) patients]. Moreover, 286 (61.8%) patients were admitted during the study period. The in-hospital mortality rate was 22.7%. 181 (39.1%) patients died within 1 year. Our multivariate analysis showed that age 85 years and older [odds ratio (OR) = 1.89; 95% confidence interval (CI): 1.36–2.63], Charlson Co-morbidity Index score ≥ 5 (OR = 3.51; 95% CI2.14–5.77), lactate ≥4 mmol/l (OR = 2.66;95% CI 1.32–5.38), quick Sequential Organ Failure Assessment (qSOFA) score ≥ 2 (OR = 5.46; 95% CI 2.94–10.12), and platelet count < 100,000 cells/mm(3) (OR = 3.19; 95% CI 1.15–8.83) were associated with 1-year mortality. CONCLUSIONS: In one middle-income country, infectious diseases account for 14.5% of elderly ED patients. Almost two-thirds of patients presenting to ED with infection are admitted to hospital. One-third of elderly ED patients with infection died within 1 year. Age ≥ 85 years, Charlson Co-morbidity Index score ≥ 5, lactate ≥4 mmol/l, qSOFA score ≥ 2, and platelet count < 100,000 cells/mm(3) predicted 1-year mortality rate.