The purpose of this study is to determine the epidemiology and outcome of sepsis at Yuetan subdistrict in Beijing in mainland China).

1. Questionnaires were used to collect the characteristic information of people living in Yuetan subdistrict in Beijing and select people who had been hospitalized because of any reasons between July 2012 and June 2014.
2. Data were collected on all patients admitted into different hospitals during the study period. The following information was recorded:demographic characteristics and admission category (whether medical, scheduled surgery, nonoperative trauma, or unscheduled surgery), presence of preexisting organ insufficiency,using definitions included in the Acute Physiology and Chronic Health Evaluation (APACHE) II score11; co- morbidities and the estimated prognosis of any preexisting underlying disease, following the classification of McCabe and Jackson.
3. Patients were included in the study cohort when having, in association with a documented or strongly suspected infection and fullfil the diagnostic criteria of sepsis according to the "Surviving Sepsis Campaign: International guidelines for management of severe sepsis and septic shock:2012".

Inclusion Criteria:

• Age≥18 years;
• Having lived in Yuetan Subdistirct for at least 1 year
• Having, in association with a documented or strongly suspected infection and fullfil the diagnostic criteria of sepsis according to the "Surviving Sepsis Campaign:International guidelines for management of severe sepsis and septic shock:2012"

Exclusion Criteria:

• Age<18 years
• Lived in Yuetan Subdistrict less than 1 year

Questionnaires were used to collect the characteristic information of people living in Yuetan subdistrict in Beijing for more than 1 years people who had been hospitalized because of any reasons between July 2012 and June 2014 were selected.Patients were included in the study cohort when having, in association with a documented or strongly suspected infection and fullfil the diagnostic criteria of sepsis according to the "Surviving Sepsis Campaign:International guidelines for management of severe sepsis and septic shock:2012".