| Primary items | |
| 1. Background | 1.1. Clearly stated research question |
| 2. Design | 2.1 Population defined |
| 2.2. Comparison groups defined and justified |
| 3. Measures | 3.1. (If relevant), exposure (e.g. treatment) is clearly defined |
| 3.2. Primary outcomes defined |
| 4. Analysis | 4.1. Potential confounders are addressed |
| 4.2. Study groups are compared at baseline |
| 5. Results | 5.1. Results are clearly presented for all primary and secondary endpoints as well as confounders |
| 6. Discussion/interpretation | 6.1. Results consistent with known information or if not, an explanation is provided |
| 6.2 The clinical relevance of the results is discussed |
| 7. Conflict of interests | 7.1. Potential conflicts of interest, including study funding, are stated |
| Secondary items |
| 1. Background | 1.1. The research is based on a review of the background literature (ideal standard is a systematic review) |
| 2. Design | 2.1. Evidence of a priori design, e.g. protocol registration in a dedicated website |
| 2.2 Population justified |
| 2.3 The data source (or database), as described, contains adequate exposures (if relevant) and outcome variables to answer the research question |
| 2.4 Setting justified |
| 3. Measures | 3.1 Sample size/Power pre-specified |
| 4. Analysis | NO SECONDARY ITEMS |
| 5. Results | 5.1. Flow chart explaining all exclusions and individuals screened or selected at each stage of defining the final sample |
| 5.2. The authors describe the statistical uncertainty of their findings (e.g. p-values, confidence intervals) |
| 5.3. The extent of missing data is reported |
| 6. Discussion/interpretation | 6.1. Possible biases and/or confounding factors described |
| 7. Conflict of interests | NO SECONDARY ITEMS |
