QUALITY of COHORT OR NESTED CASE-CONTROL STUDIES

UI Author Year Population Exposure (All) Dietary assessment * Biomarkers * Comparator Statistical Analysis Outcome Design
19001601 Flood 2008 a) Eligibility criteria clear? (y/n) Y a) Exposure assessor blinded to outcome info? (y/n) Nd a) Method reported? (y/n) Y a) One of the prespecified methods *** was used? (y/n) NA a) Level of the exposure in comparative categories (eg quartiles) is given (ranges)? (y/n) applicable for categorical analyses only y a) Adjusted or matched for ANY confounders (other than age and sex)? ** (y/n) y but not used eventually a) Clear definition of outcome, including time of ascertainment? (y/n) y a) Prospective collection of data? (y/n) Y
b) Sampling of population random or consecutive? (y/n) Y “all” b) Outcome assessor blinded to exposure measurement? (y/n) nd b) Food composition database or suppl composition reported? (y/n) Y Time from sample collection to sample analysis reported? (y/n) NA b) Loss to follow-up <20%? (y/n) Y (90.3%) b) Analysis was planned when cohort was formed? (y/n) N
c) Internal calibration of method perform (if FFQ)? (y/n/NA) y b) Justification of final adjusted model selection? (y/n) Y “not materially altered” c) Do the authors specify a primary outcome? (y/n) n c) ustification 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): Post-hoc analysis of an already available database. Otherwise, the reporting is good except for the blinding of the assessors of exposure and outcomes; not all cases confirmed by histology; participants per calcium quintile not reported; power calculation not reported
*

Check “NA” and skip all questions if study did not use dietary assessment or biomarkers

**

We will judge in the end if the set of confounders is adequate

***

Prespecified methods: HPLC, RIA kits, LC-MS/MS; EIA/Chemiluminescence

From: Appendix C, Evidence Tables: F-K

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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