Table 2. Methodological characteristics of the published epidemiological studies on SARS.
| Characteristic (n Articles) | Category | Subcategory | n (%a) Studies |
| Type of study (152) | Descriptive epidemiology | 82 (54) | |
| Analytical epidemiology | 45 (30) | ||
| Theoretical epidemiology | 16 (11) | ||
| Experimental epidemiology | 9 (6) | ||
| Study design (152) | Cross-sectional studies | 30 (20) | |
| Cohort studies | Descriptive (longitudinal) cohort | 32 (21) | |
| Prospective cohort | 12 (8) | ||
| Historical cohort | 20 (13) | ||
| Case-control studies | 8 (5) | ||
| Experimental studies | Intervention trials | 2 (1) | |
| Clinical trials | 7 (5) | ||
| Mathematical modeling | 16 (11) | ||
| Molecular studies | 11 (7) | ||
| Diagnostic studies | 14 (9) | ||
| Case-definition (118) | WHO and/or CDC case definition | 80 (68) | |
| Local health authority's or authors' case definition | 19 (16) | ||
| Not specified | 19 (16) | ||
| Study setting (152) | Hospital | 106 (70) | |
| Community | 33 (22) | ||
| Hospital and community | 13 (9) | ||
| Data-collection instrument b (152) | Questionnaire | 50 (33) | |
| Biological specimen collection | 60 (39) | ||
| Physical examinations | 33 (22) | ||
| Environmental sample | 2 (1) | ||
| Hospital, medical, or exposure records | 20 (13) | ||
| Secondary datac | 49 (32) | ||
| Not specified | 2 (1) | ||
| Quality-assurance processes for data collection (152) | Indicated in the article | 53 (35) | |
| Not specified | 99 (65) | ||
| Quality-control activities for data collection (152) | Indicated in the article | 19 (13) | |
| Not specified | 133 (88) | ||
| Software for database management (152) | Indicated in the article | 8 (5) | |
| Not specified | 144 (95) | ||
| Software for data analysis (114) | Indicated in the article | 66 (58) | |
| Not specified | 48 (42) |
a
Percentages do not add up to 100 because of rounding figures.
b
Percentages in this section do not add up to 100% because multiple answers were possible.
c
Reanalysis of previously used data.