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. Author manuscript; available in PMC: 2015 Apr 1.
Published in final edited form as: JAMA Surg. 2014 Apr 1;149(4):383–392. doi: 10.1001/jamasurg.2013.4059

Table 3.

Quality of included studies as assessed by Newcastle-Ottawa Scale (NOS) and type of bias identified.

Study Design NOS Types of Bias (Confounders)
McCarthy18 Retrospective case series ***

  • Selection (study period, various malignancies, +/− adjuvant therapy)

  • Performance (study period, various malignancies)
Turnbull19 Retrospective case series ***

  • Selection (study period, various malignancies, prior operations, unclear inclusion criteria, urgent vs. elective)

  • Performance (study period, various malignancies, urgent vs. elective)
Lau20 Retrospective case series **

  • Selection (study period, +/− adjuvant therapy, urgent vs. elective)

  • Performance (study period, urgent vs. elective)
Van Ooijen21 Retrospective cohort study ***

  • Selection (study period, various malignancies, +/− adjuvant therapy, unclear inclusion criteria, crossover between groups)

  • Performance (study period, various malignancies, +/− postoperative chemotherapy, crossover between groups)

  • Detection (crossover between groups)
Blair22 Retrospective case series ***

  • Selection (unclear inclusion criteria)
Legendre23 Retrospective case series **

  • Selection (study period, various malignancies, +/− adjuvant therapy, unclear inclusion criteria)

  • Performance (study period, various malignancies)

  • Detection (complications not described, oral intake not described)
Abbas24,25 Retrospective case series ***

  • Selection (study period, various malignancies, +/− adjuvant therapy, unclear inclusion criteria)

  • Performance (study period, various malignancies)

  • Detection (complications not described)
Piver26 Retrospective case series **

  • Selection (study period, +/− adjuvant therapy, unclear inclusion criteria)

  • Performance (study period, variable postoperative chemotherapy)
Lund27 Retrospective cohort study ******

  • Selection (unclear inclusion criteria)
Rubin28 Retrospective cohort study ******

  • Selection (+/− adjuvant therapy, unclear inclusion criteria, multiple analyses of patients)

  • Performance (multiple analyses of patients)

  • Detection (multiple analyses of patients)
Bais29 Retrospective cohort study *****

  • Selection (study period, +/− adjuvant therapy)

  • Performance (study period, +/− postoperative chemotherapy)
Jong30 Retrospective case series ***

  • Selection (study period, +/− adjuvant therapy, unclear inclusion criteria)

  • Performance (study period)

  • Detection (complications not described)
Pothuri31 Retrospective case series ***

  • Selection (+/− adjuvant therapy, unclear inclusion criteria, multiple analyses of patients)

  • Performance (+/− postoperative chemo- and radiotherapy, multiple analyses of patients)

  • Detection (multiple analyses of patients)
Mangili32 Retrospective cohort study *****

  • Selection (unclear study period)

  • Performance (unclear study period)
Chi33 Prospective cohort study *****

  • Selection (+/− adjuvant therapy, unclear inclusion criteria)

  • Performance (+/− postoperative chemotherapy)
Kim34 Retrospective case series **

  • Selection (study period, unclear inclusion period)

  • Performance (study period)

  • Attrition (patients with limited follow up/lost to follow up)
Kolomainen35 Retrospective case series **

  • Selection (study period, +/− adjuvant therapy, unclear inclusion criteria)

  • Performance (study period, +/− postoperative chemotherapy)