| Reference | Comments |
|---|---|
| «Siddiqi K, Shah S, Abbas SM ym. Global burden of d...»1 | Swedish studies include 4, 6, 9, 10 In included studies exposure and comparison heterogenic, in some studies also unreliable and questionable eg. deceased cases and controls included [4], dose and duration of snuff use often lacking, comparisons made between snuff users and smokers instead of never users of any tobacco products. |
| «Asthana S, Labani S, Kailash U ym. Association of ...»3 | European studies include 4, 6, 9 |
| «Schildt EB, Eriksson M, Hardell L ym. Oral snuff, ...»4 | Exposure may be confounded: deceased cases and their deceased controls were included,
(questionnaire filled by relatives). Eligibility may be confounded: Only one female reported snuff use. Study design/outcome measures: Mortality was not analyzed although 235 cases were deceased *Reporting: oral cancer risk ORs for snuff using ex-smokers and smokers are confusing compared to reported absolute numbers of cases |
| «Roosaar A, Johansson AL, Sandborgh-Englund G ym. C...»5 | Eligibility may be confounded: Only men included (no snuff using females in the cohort)
Exposure may be confounded: recorded only in the beginning |
| «Luo J, Ye W, Zendehdel K ym. Oral use of Swedish m...»6 | Eligibility may be confounded: females were excluded Exposure may be confounded: recorded only in the beginning Selective reporting: big cohort, mortality not analyzed |
| «Timberlake DS, Nikitin D, Johnson NJ ym. A longitu...»7 | Exposure may be confounded: recorded only in the beginning
Control of confounding factors: not adjusted to alcohol use (not recorded) Median follow up-time quite short (8,8 years) for all-cause mortality |
| «Hansson J, Galanti MR, Hergens MP ym. Snus (Swedis...»8 | Exposure may be confounded: recorded only in the beginning,
Eligibility confounded: only men included Reporting: current snuff users compared to noncurrent use (not to never use) |
| «Sinha DN, Suliankatchi RA, Gupta PC ym. Global bur...»9 | Significant heterogeneity between studies I2= 92,7
All included studies had moderate risk for exposure bias, 9/16 studies moderate risk for confounding factors |