|
Study Characteristics That Influence Results |
| Characteristics That Influence Applicability |
| Treatment specifics |
| Details of procedure |
| Details of ancillary treatments or management of intermediate outcomes |
| Outcome |
| Definition |
| Method of patient contact and assessment at follow-up |
| Length of follow-up |
| Patient characteristics |
| Study setting |
| Inclusion/exclusion criteria |
| Reported characteristics |
| Characteristics That Influence Validity |
| Information bias |
| Incorrectly ascertaining treatment or outcome |
| Selection bias |
| Pretreatment – subjects on different treatments have different risks |
| Post treatment – lost to follow-up depends on outcome and treatment |
| Confounding |
| Caused by pretreatment selection bias |
| Demonstrated by differences in risk factors between treatment groups |
| Possibly reduced by risk-adjustment |
Hartz et al. Emerging Themes in Epidemiology 2005 2:8 doi:10.1186/1742-7622-2-8 |