Teleman 2004.

Methods	Case‐control study assessing risk and protective factors in HCWs during the SARS outbreak in Singapore (1 to 22 March 2003)
Participants	Description of cases: 36 HCWs admitted with probable SARS (according to WHO definition) during 1 to 31 March 2003. Six others were too ill to speak and 2 others died Description of controls: 50 HCWs working on the same wards who had definite exposure to SARS (physical proximity of 1 metre or less of a patient subsequently diagnosed as having SARS) but did not develop SARS
Interventions	Data on personal details and symptoms and exposure were gathered via a closed phone questionnaire. The 2 groups were comparable for demographic and epidemiological characteristics except that non‐Chinese ethnic groups were twice as common among controls The following risk factors were assessed: Distance from source of infection < 1 metre Duration of exposure 60 or more minutes Wearing N95 respirator Wearing gloves Wearing gown Touched patients Touched patients' personal belongings Contact with respiratory secretions Performed venepuncture Performed or assisted in intubation Performed suction of body fluids Administered oxygen Handwashing after each patient
Outcomes	SARS
Notes	Risk of bias: low Notes: the authors conclude that 3 factors were associated with significant risks or protection: Wearing N95 respirator OR 0.1 (95% CI 0.02 to 0.86) Contact with respiratory secretions OR 21.8 (95% CI 1.7 to 274.8) Handwashing after each patient OR 0.07 (95% CI 0.008 to 0.66) A well‐reported study, let down by the failure to indicate whether assessment of risk factors had been carried out blindly to cases or control status. We wonder how much of the non‐significance for certain factors is due to lack of statistical power
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	N/A
Allocation concealment (selection bias)	Unclear risk	N/A
Blinding (performance bias and detection bias) All outcomes	Unclear risk	N/A
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	N/A
Selective reporting (reporting bias)	Unclear risk	N/A