| Methods |
Retrospective cohort study carried out in selected precincts of Haidian district of Beijing, People's Republic of China between March and May 2003 during the epidemic of SARS (attack rate 19/100,000 population in the period March to July). Precincts were chosen on the basis of the highest number of quarantinees. The study aimed at assessing the risk of acquiring SARS among quarantinees. A better definition of the risk would help in future to identify better candidates for quarantine and target resources accordingly. The study was based on a questionnaire‐based survey on the reasons for quarantine. SARS diagnosis for contacts was independently carried out from lists |
| Participants |
171 SARS cases (29% of total) were identified in the precincts and 1210 persons (23%) quarantined from the selected districts (contacts). These were sampled from a total population of 2.24 million, with 5.186 quarantinees. Response rate was 85% (1.028 quarantinees who completed the questionnaire, of which 232 developed probable SARS while in quarantine) |
| Interventions |
Quarantine at home or hospital for 14 days post‐exposure (reduced to 10 and then to 3). Quarantine is defined as the separation and or restriction of movement of persons who due to recent exposure to a communicable disease risk acquiring the disease and transmitting to third parties.
A contact was defined as:
‐ Healthcare worker not using personal protective equipment (PPE) when caring for/assessing a SARS case:
‐ other persons caring for a SARS case
‐ persons sharing accommodation with a SARS case
‐ persons visiting a SARS case
‐ persons working with a SARS case
‐ classmates or teachers of a SARS case
‐ persons sharing the same means of public transport with a SARS case
All quarantinees were followed up daily and were admitted to hospital if they developed fever (38 °C or more) |
| Outcomes |
Laboratory: no
Effectiveness: definition of SARS was based on criteria of Chinese Ministry of Health. Definition was clinical and not based on laboratory isolation of the SARS‐CoV
Safety: N/A |
| Notes |
Risk of bias: high
Notes: the authors conclude that only those quarantinees who actually had home or hospital contact with a symptomatic SARS patient developed the illness (attack rate 31.1, 95% CI 20.2 to 44.4 for carers, 8.9%, 95% CI 2.9 to 22.1 for visitors, 4.6%, 95% CI 2.3 to 8.9 for those who lived with a SARS case) but not those living in the same building or working with them and not contacts of any SARS case during the incubation period. Fever was also not a good reason to quarantine people (attack rate nil). Quarantine also appeared to prevent transmission, although there were numerous cases in which quarantine was not required. There are several limitations to the conclusion of the study Non‐random basis for the sample, selection bias of the sample and responders, recall bias of responders and the absence of a laboratory‐confirmed diagnosis may have affected the conclusion one way or another
Overall, not enough denominator data, non‐exposed data are given to allow data extraction or calculate OR |
| 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 |
