Table 1

Levels of evidence according to Kingston et al12 (n=252)

LevelStudy designNo of patients (%)
1Systematic review26 (10.3%)
2Meta-analysis 2 (0.8%)
3Randomised controlled trial80 (31.7%)
4Prospective study34 (13.5%)
5Retrospective study52 (20.6%)
NoneNo evidence or evidence opposed the intervention58 (23.0%)