Smoking Exposure and Survival of Patients with Esophagus Cancer: A Systematic Review and Meta-Analysis

Table 3

Results of quality assessment by Newcastle-Ottawa Scale.

Study	1	2	3	4	5A	5B	6	7	8	Scores
Case control
Zhang et al. [10]	☆	☆	☆	☆	—	—	☆	☆	☆	7
Shitara et al. [12]	☆	☆	☆	☆	☆	☆	☆	☆	—	8
Lin et al. [13]	☆	☆	☆	☆	☆	☆	☆	☆	—	8
Mirinezhad et al. [15]	☆	☆	☆	☆	—	—	☆	☆	☆	7
Thrift et al. [16]	☆	—	☆	☆	☆	☆	☆	☆	☆	8
Sundelöf et al. [17]	☆	☆	☆	☆	☆	☆	☆	☆	—	8
Trivers et al. [11]	☆	☆	☆	☆	☆	☆	☆	—	—	7
Cohort
Wu et al. [14]	☆	☆	☆	☆	—	☆	☆	☆	☆	8

For case-control studies, 1 indicates adequate definition of cases, 2 cases are representative of population, 3 community controls, 4 controls have no history of smoking, 5A study controls for age and gender, 5B study controls for additional factor(s), 6 ascertainment of exposure by blinded interview or record, 7 the same method of ascertainment used for cases and controls, and 8 nonresponse rate the same for cases and controls. For cohort studies, 1 indicates exposed cohort truly representative, 2 nonexposed cohort drawn from the same community, 3 ascertainment of exposure, 4 outcome of interest not present at start, 5A cohorts comparable on basis of age and gender, 5B cohorts comparable on other factor(s), 6 quality of outcome assessment, 7 follow-up long enough for outcomes to occur (at least 1 year), and 8 complete accounting for cohorts (75% follow-up or description provided of those lost). Newcastle-Ottawa Scale (NOS): see: http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp.