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Table 3 Level of evidence

From: Development and validation of a guideline on sexual and reproductive health services for polycystic ovary syndrome in Iran: a mixed-methods study protocol

Level Definition
1: Strong Randomized clinical trials or their meta-analysis
2: Intermediate Non-randomized clinical trials and their meta-analysis
Case–control studies or their meta-analysis
Prospective cohort studies
3: Weak Cross-sectional studies, observational studies, case series or case reports
4: No evidence Insufficient evidence