Table 4.
Quality assessment for included studies based on NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies (n = 19).
| Mayanagi 2017 | Ida 2014 (38) | Reisinger 2015 (40) | Liu 2016 (41) | Miyata 2017 (24) | Guinan 2017 (42) | Motoori 2018 (18) | Jarvinen 2018 (43) | Ozawa 2019 (29) | Yassaie 2019 (30) | Yoon 2020 (37) | Kawakita 2020 (26) | Hagens 2020 (44) | Boer 2020 (27) | Matsuura 2019 (36) | Zhang 2021 (25) | Levolger 2017 (17) | Nardi 2019 (23) | Fukuoka 2019 (16) | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Was the research question or objective in this paper clearly stated? | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 2 | Was the study population clearly specified and defined? | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 3 | Was the participation rate of eligible persons at least 50%? | Y | Y | Y | Y | N | Y | Y | Y | Y | N | Y | Y | Y | NR | Y | Y | N | NR | Y |
| 4 | Were all the subjects selected or recruited from the same or similar populations? | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 5 | Was a sample size justification, power description, or variance and effect estimates provided? | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N |
| 6 | For the analyses in this paper, were the exposure(s) of interest measured prior to the outcome(s) being measured? | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 7 | Was the timeframe sufficient so that one could reasonably expect to see an association between exposure and outcome if it existed? | Y | Y | Y | Y | Y | NR | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 8 | For exposures that can vary in amount or level, did the study examine different levels of the exposure as related to the outcome (e.g., categories of exposure, or exposure measured as continuous variable)? | N | N | N | Y | N | N | Y | Y | N | Y | Y | Y | N | Y | Y | Y | N | Y | Y |
| 9 | Were the exposure measures (independent variables) clearly defined, valid, reliable, and implemented consistently across all study participants? | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 10 | Was the exposure(s) assessed more than once over time? | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 11 | Were the outcome measures (dependent variables) clearly defined, valid, reliable, and implemented consistently across all study participants? | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 12 | Were the outcome assessors blinded to the exposure status of participants? | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 13 | Was loss to follow-up after baseline 20% or less? | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 14 | Were key potential confounding variables measured and adjusted statistically for their impact on the relationship between exposure(s) and outcome(s)? | Y | N | N | Y | N | N | Y | Y | Y | N | Y | Y | Y | Y | Y | Y | Y | N | Y |
| Conclusion (A: Good; B: Fair; C: Poor) | B | B | B | A | B | B | A | B | B | B | A | A | B | A | A | A | B | B | A | |
Y, yes; N, no; NR, not reported; NA, not applicable.