各级别临床研究的证据等级
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3838756/
Articles on treatment
| Studies of Therapy | |||
|---|---|---|---|
| Class | Bias risk | Study design | Criteria |
| I | Low risk Study adheres to commonly held tenets of high quality design, execution and avoidance of bias |
Good quality RCT | · Random sequence generation · Allocation concealment · Intent-to-treat analysis · Blind or independent assessment for important outcomes · Co-interventions applied equally · F/U rate of 80%+ · Adequate sample size |
| II | Moderately low risk Study has potential for some bias; study does not meet all criteria for class I, but deficiencies not likely to invalidate results or introduce significant bias |
Moderate or poor quality RCT Good quality cohort |
· Violation of one of the criteria for good quality RCT · Blind or independent assessment in a prospective study, or use of reliable dataa in a retrospective study · Co-interventions applied equally · F/U rate of 80%+ · Adequate sample size · Controlling for possible confoundingb |
| III | Moderately High risk Study has significant flaws in design and/or execution that increase potential for bias that may invalidate study results |
Moderate or poor quality cohort Case-control |
· Violation of any of the criteria for good quality cohort · Any case-control design |
| IV | High risk Study has significant potential for bias; lack of comparison group precludes direct assessment of important outcomes |
Case series | · Any case series design |
aOutcome assessment is independent of healthcare personnel judgment. Reliable data are data such as mortality or re-operation.
bAuthors must provide a description of robust baseline characteristics, and control for those that are unequally distributed between treatment groups.
Articles on prognosis or risk
| Studies of prognosis | |||
|---|---|---|---|
| Class | Risk of bias | Study design | Criteria |
| I | Low risk Study adheres to commonly held tenets of high quality design, execution and avoidance of bias |
Good quality cohorta | · Prospective design · Patients at similar point in the course of their disease or treatment · F/U rate of ≥ 80%b · Patients followed long enough for outcomes to occur · Accounting for other prognostic factorsc |
| II | Moderately low risk Study has potential for some bias; does not meet all criteria for class I but deficiencies not likely to invalidate results or introduce significant bias |
Moderate quality cohort | · Prospective design, with violation of one of the other criteria for good quality cohort study · Retrospective design, meeting all the rest of the criteria in class I |
| III | Moderately high risk Study has flaws in design and/or execution that increase potential for bias that may invalidate study results |
Poor quality cohort Good quality case-control or cross-sectional study |
· Prospective design with violation of 2 or more criteria for good quality cohort, or · Retrospective design with violation of 1 or more criteria for good quality cohort · A good case-control studyd · A good cross-sectional studye |
| IV | High risk Study has significant potential for bias; does not include design features geared toward minimizing bias and/or does not have a comparison group |
Poor quality case-control or cross-sectional Case seriesd |
· Other than a good case-control study · Other than a good cross-sectional study · Any case seriesf design |
aCohort studies follow individuals with the exposure of interest over time and monitor for occurrence of the outcome of interest.
bApplies to cohort studies only.
cAuthors must consider other factors that might influence patient outcomes and should control for them if appropriate.
dA good case-control study must have the all of the following: all incident cases from the defined population over a specified time period, controls that represent the population from which the cases come, exposure that precedes an outcome of interest, and accounting for other prognostic factors.
eA good cross-sectional study must have all of the following: a representative sample of the population of interest, an exposure that precedes an outcome of interest (e.g., sex, genetic factor), an accounting for other prognostic factors, and for surveys, at least a 80% return rate.
fA case-series design for prognosis is one where all the patients in the study have the exposure of interest. Since all the patients have the exposure, risks of an outcome can be calculated only for those with the exposure, but cannot be compared with those who do not have the exposure. For example, a case-series evaluating the effect of smoking on spine fusion that only recruits patients who smoke can simply provide the risk of patients who smoke that result in pseudarthrosis but cannot compare this risk to those that do not smoke.