QUALITY of COHORT OR NESTED CASE-CONTROL STUDIES

UI Author Year Population Exposure (All) Dietary assessment* Biomarkers* Comparator Statistical Analysis Outcome Design
15531500 Sambrook 2004 a) Eligibility criteria clear? (y/n) Y a) Exposure assessor blinded to outcome info? (y/n) N a) Method reported? (y/n) Y a) One of the prespecified methods*** was used? (y/n) Y a) Level of the exposure in comparative categories (e.g. quartiles) is given (ranges)? (y/n) applicable for categorical analyses only N a) Adjusted or matched for ANY confounders (other than age and sex)?** (y/n) Y a) Clear definition of outcome, including time Y of ascertainment? (y/n) Y a) Prospective collection of data? (y/n) Y
b) Sampling of population random N or consecutive? (y/n) N b) Outcome assessor blinded to exposure measurement? (y/n) N b) Food composition database or suppl composition reported? (y/n) N Time from sample collection to sample analysis reported? (y/n) N b) Loss to follow-up N <20%? (y/n) N b) Analysis was planned when cohort was formed? (y/n) nd
c) Internal calibration of method perform (if FFQ)? (y/n/NA) N b) Justification of final adjusted model selection? (y/n) N c) Do the authors specify a primary outcome? (y/n) Y c) Justification of sample size (includes sample size calculations)? (y/n) N
OVERALL Grade (A/B/C): C
Explanation for Overall Quality Grade (if not Grade A): did not adjust for dietary factors, anthropometrics and additional variables relevant to vitamin D

From: Appendix C, Evidence Tables: R-Z

Cover of Vitamin D and Calcium
Vitamin D and Calcium: A Systematic Review of Health Outcomes.
Evidence Reports/Technology Assessments, No. 183.
Chung M, Balk EM, Brendel M, et al.

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