Table 4. Comparison of the epidemiology of systematic reviews in 2004 and 2014.
| Characteristic | Category | Year | |
|---|---|---|---|
| 2004 (n = 300) | 2014 (n = 300) | ||
| Total number of journals | 132 | 185 | |
| Number of SRs per journal | 1 | 102/132 (77%) | 141/185 (76%) |
| 2 | 21/132 (16%) | 30/185 (16%) | |
| 3 | 6/132 (5%) | 8/185 (4%) | |
| ≥4 | 3/132 (2%) | 6/185 (3%) | |
| Journal impact factor | 0.0–5.0 | 106 (35%) | 187 (62%) |
| 5.1–10 | 19 (6%) | 74 (25%) | |
| 10.1–15 | 1 (1%) | 4 (1%) | |
| >15 | 4 (1%) | 5 (2%) | |
| No impact factor | 170 (57%) | 30 (10%) | |
| Number of authors | 1 | 24 (8%) | 5 (2%) |
| 2–3 | 125 (42%) | 64 (21%) | |
| 4–6 | 128 (43%) | 162 (54%) | |
| ≥7 | 23 (8%) | 69 (23%) | |
| Country of corresponding author | China | <10 (<3%) | 62 (21%) |
| UK | 76 (25%) | 47 (16%) | |
| US | 68 (23%) | 46 (15%) | |
| Canada | 28 (9%) | 27 (9%) | |
| The Netherlands | 17 (6%) | 18 (6%) | |
| Australia | 31 (10%) | 16 (5%) | |
| Germany | 10 (3%) | 10 (3%) | |
| Other (<10 reviews/country, 30 countries) | 60 (20%) | 74 (25%) | |
| Focus of review | Therapeutic (treatment/prevention) | 213 (71%) | 164 (55%) |
| Epidemiology (prevalence, associations/etiology) | 38 (13%) | 74 (25%) | |
| Diagnosis/prognosis | 23 (8%) | 33 (11%) | |
| Other (e.g., education, review of psychometric properties, barriers analysis, cost of illness) | 46 (15%) | 29 (10%) | |
| Common ICD-10 codes | Neoplasms (including cancers, carcinomas, tumors) | 22 (7%) | 49 (16%) |
| Infections and parasitic diseases | 20 (7%) | 41 (14%) | |
| Diseases of the circulatory system | 33 (11%) | 34 (11%) | |
| Diseases of the digestive system | 20 (7%) | 25 (8%) | |
| Endocrine, nutritional, and metabolic diseases | — | 23 (8%) | |
| Mental and behaviour disorders | 40 (13%) | 22 (7%) | |
| Diseases of the musculoskeletal system | — | 20 (7%) | |
| Cochrane review | 60 (20%) a | 45 (15%) | |
Data given as number (percent).
aIn 2004, Cochrane reviews were published quarterly, of which 125 were indexed in November 2004. The value presented here has been standardized to a monthly estimate.