ABSTRACTBackground:We investigated the time to death and factors associated with deaths from dengue and chikungunya during the first epidemic after the introduction of the chikungunya virus in Northeastern Brazil.Methods:This retrospective cohort study was conducted in Pernambuco between 2015 and 2018. Logistic regression was used to identify independent risk factors. The probability of survival among individuals with different arbovirus infections was estimated and the survival curves were compared using log-rank tests.Results:The lethality coefficients for dengue and chikungunya viruses were 0.08% and 0.35%, respectively. The chance of death due to chikungunya infection increased progressively from the age of 40 years. At 40-49 years, the odds ratio was 13.83 (95%CI, 1.80-106.41). At 50-59 years and 60 years or older, the odds ratio was 27.63 (95%CI, 3.70-206.48); and 78.72 (95%CI, 10.93-566.90), respectively. The probability of death associated with dengue virus infection increased from the age of 50 years. Among patients aged 50-59 years and 60 years or older, the odds ratio was 4.30 (95%CI, 1.80-10.30) and 8.97 (95%CI, 4.00-20.0), respectively. Independent factors associated death were headache and age of 50 years or older for dengue; and headache, nausea, back pain, intense arthralgia, age 0-9 years or 40 years and older, and male sex for chikungunya. The ratio between mortality rates revealed that the time to death from dengue was 2.1 times faster than that from chikungunya (95%CI, 1.57-2.72).Conclusions:The time to death was shorter in patients with dengue than in those with chikungunya disease. This study reinforces the need for faster and more effective decision-making in public health services to enhance patient outcomes and minimize mortality.