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Table 1 Levels of clinical evidence

From: Reviewing the evidence on effectiveness and cost-effectiveness of HIV prevention strategies in Thailand

A+

Systematic reviews & meta-analyses of RCTs or RCT(s) conducted in Thailand with a very low risk of bias*.

A

Systematic reviews & meta-analyses of RCTs or RCT(s) conducted internationally with a very low risk of bias.

B+

Systematic reviews & meta-analyses of RCTs or RCT(s) conducted in Thailand with a high risk of bias.

B

Systematic reviews & meta-analyses of RCTs or RCT(s) conducted internationally with a high risk of bias.

C+

Systematic reviews of case control or cohort studies conducted in Thailand with a very low risk of confounding, bias, or chance and a high probability that the relationship is causal.

C

Systematic reviews of case control or cohort studies conducted internationally with a very low risk of confounding, bias, or chance and a high probability that the relationship is causal.

D+

Case control or cohort studies conducted in Thailand with a high risk of confounding, bias, or chance and a significant risk that the relationship is not causal.

D

Case control or cohort studies conducted internationally with a high risk of confounding, bias, or chance and a significant risk that the relationship is not causal.

  1. * A bias is a systematic error, or deviation from the truth, in results or inferences.
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BMC Public Health

ISSN: 1471-2458

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