Zynx Health Evidence Classification System

All references in Zynx products are classified based on study design, according to the Zynx Health Evidence Classification System as follows:

Class A Evidence

Randomized controlled trials. These studies generally have the following characteristics:

• Study participants are randomized to an intervention or control group.
• Study participants are enrolled prior to measurement of outcomes.

Class B Evidence

Nonrandomized prospective studies. These include the following study designs:

• Studies that make comparisons between contemporaneous patients, or between current and former patients
• Noncontrolled case series that study 10 or more patients

Class C Evidence

Retrospective studies.

Class E Evidence

Articles that are based on or represent the following:

• Expert opinion.
• Guidelines.
• Consensus statements.
• Articles that catalogue or summarize data and/or results contained within other articles (without performing any further statistical analysis)
• Case reports of fewer than 10 patients.
• Summary data presented in textbooks.

Class M Evidence

Meta-analyses. Meta-analyses use an explicitly stated methodology to identify literature to address a specific question and involve the calculation of pooled effect sizes.

Class P Evidence  

Performance measures.  Performance measures are quality metrics that relate to a process of care or outcome.

Class Q Evidence

Studies in which the primary goals, methods, and results represent economic evaluations involving any one or more of the following analyses:

• Cost-benefit
• Cost-effectiveness
• Cost-identification
• Cost-minimization
• Cost-utility
• Decision analysis (eg, Markov model) with or without economic outcomes

Class S Evidence

Systematic reviews. Systematic reviews use an explicitly stated methodology to identify literature to address a specific question but do not calculate pooled effect sizes.