Table 1. Proportions of each study design in 1998 and 2013.
| 1998 | 2013 | |||
|---|---|---|---|---|
| Types of study | Including transplant studies | Excluding transplant studies | Including transplant studies | Excluding transplant studies |
| Less appropriate study designs as per the IDEAL recommendations | ||||
| Overall | 1620 (89%) | 1419 (89.8%) | 3497 (85.3%) | 2941 (85.2%) |
| Case Studies | 710 (39%) | 661 (41.8%) | 1318 (32.1%) | 1222 (35.4%) |
| Retrospective case series or retrospective cohort study | 856 (47%) | 712 (45%) | 2046 (49.9%) | 1615 (46.8%) |
| Case-Control Study | 54 (3%) | 46 (2.9%) | 133 (3.2%) | 104 (3.0%) |
| More appropriate study designs as per the IDEAL recommendations | ||||
| Overall | 195 (10.7%) | 156 (9.8%)# | 498 (12.1%) | 410(11.9%)# |
| Prospective Cohort Studies | 137 (7.5%) | 110 (7%) | 388 (9.5%) | 316 (9.2%) |
| Randomised Controlled Trials | 32 (1.8%) | 29 (1.8%) | 71 (1.7%) | 65 (1.9%) |
| Long-term follow-up | 26 (1.4%) | 17 (1.1%) | 39 (1.0%) | 29 (0.8%) |
| Not classified in IDEAL recommendations | ||||
| Systematic Review | 6 (0.3%) | 6 (0.4%) | 105 (2.6%) | 102 (2.9%) |
| Total | 1821 | 1581 | 4100 | 3453 |
#Difference in proportion utilising appropriate study designs = 2.3% (95% CI 0.5%-4%, p = 0.017). Comparison made excluding transplant studies