Table 2.

Newcastle-Ottawa score⁶ for the cohort studies included in the systematic review

Study	Representativeness of participants	Selection of nonexposed cohort	Ascertainment of exposure	Outcome not present	Comparability of controls	Assessment of outcome	Adequate follow-up	Loss to follow-up	Total score
Kluger et al.8	Somewhat representative*	No control group	Prospective cohort*	Yes*	No control	Prospective cohort*	Yes*	None reported*	6/9
Jacobs et al.9	Somewhat representative*	No control group	Prospective cohort*	Yes*	No control	Prospective cohort*	Yes*	None reported*	6/9
Jacobs et al.10	Somewhat representative*	No control group	Prospective cohort*	Yes*	No control	Prospective cohort*	Yes*	None reported*	6/9
Gaarder et al.11	Truly representative*	No control group	Prospective cohort*	Yes*	No control	Prospective cohort*	Yes*	None reported*	6/9
King et al.13	Somewhat representative*	No control group	Prospective cohort*	Yes*	No control	Prospective cohort*	Yes*	None reported*	6/9
Tugnoli et al.14	Somewhat representative*	No control group	Prospective cohort*	Yes*	No control	Prospective cohort*	Yes*	None reported*	6/9
Sohn et al.15	Somewhat representative*	No control group	Prospective cohort*	Yes*	No control	Prospective cohort*	Yes*	None reported*	6/9
Sohn et al.16	Somewhat representative*	No control group	Prospective cohort*	Yes*	No control	Prospective cohort*	Yes*	None reported*	6/9
Rubiano et al.17	Somewhat representative*	No control group	Prospective cohort*	Yes*	No control	Prospective cohort*	Yes*	None reported*	6/9
McLaughlin et al.19	Somewhat representative*	No control group	Prospective cohort*	Yes*	No control	Prospective cohort*	Yes*	None reported*	6/9

Refer to Wells et al.⁶ for a description of Newcastle–Ottawa Quality Assessment Scale for cohort studies. In general, more stars denote higher quality. Representativeness is awarded a star if the cohort is truly or somewhat representative of the population of interest. For selection of the nonexposed cohort, a star is awarded if it is drawn from the same population as the exposed cohort. The relevant exposure in this review is the surgical procedure performed in the live tissue; we considered a nonexposed cohort to be one that performed the procedure in another simulation method. Exposure is satisfactorily ascertained if data are collected from a secure record. A star is awarded if the outcome is not present at the start of the study. A maximum of 2 stars can be given for comparability of controls for controlling of confounders in either the design (matching) or analysis (statistical adjustment) phase. We also gave 1 star when selection criteria appeared to create comparable groups via restriction. Assessment of outcome is awarded a star if the outcomes were assessed by independent blind assessment or record linkage. The duration of follow-up was considered adequate if it was long enough for the outcomes to occur. Completeness of follow-up was considered adequate if all participants were accounted for or if the number lost to follow-up was sufficiently low to be unlikely to introduce bias.