Indication for treatment can introduce bias in observational studies of surgical treatment.
Holmberg
L
L
Steineck
G
G
D015986:Confounding Factors, Epidemiologic; D006801:Humans; D009369:Neoplasms / Q000601:surgery*; D015588:Observer Variation; D016032:Randomized Controlled Trials as Topic; D012107:Research Design; D013514:Surgical Procedures, Operative / Q000592:standards; D015996:Survival Rate