Empirical evaluation of meta-analytic approaches for nutrient and health outcome dose-response data.
The objective of this study is to empirically compare alternative meta-analytic methods for combining dose-response data from epidemiological studies. We identified meta-analyses of epidemiological studies that analyzed the association between a single nutrient and a dichotomous outcome. For each topic, we performed meta-analyses of odds ratios with five approaches: using extreme exposure categories only, two-step approach (first calculated study-specific effects then combined across studies) using unadjusted data, two-step approach using adjusted data, one-step approach (analyzed all data in one regression model) using unadjusted data, and one-step approach using adjusted data. Meta-analyses including only extreme exposure categories gave consistently bigger effects and wider confidence intervals than meta-analyses using all data. Confidence intervals of effect sizes were generally wider in meta-analyses with the two-step approach, compared with the one-step approach. Meta-analyses using unadjusted data and adjusted data differed, with no consistent pattern of discordance in direction, statistical significance, or magnitude of effect. We discourage using meta-analysis approaches that only use data from extreme exposure categories. The one-step approach generally has higher precision than the two-step approach. Sensitivity analysis comparing results between meta-analyses of adjusted and unadjusted data may be useful in indicating the presence of confounding.
Tufts Evidence-Based Practice Center, Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, MA, USA.
Winifred W
WW
Yu
Christopher H
CH
Schmid
Alice H
AH
Lichtenstein
Joseph
J
Lau
Thomas A
TA
Trikalinos
D015984:Causality; D015897:Comorbidity; D003627:Data Interpretation, Statistical; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D064420:Drug-Related Side Effects and Adverse Reactions / Q000401:mortality*; D000066506:Heuristics; D006801:Humans; D015994:Incidence; D015201:Meta-Analysis as Topic; D017063:Outcome Assessment, Health Care / Q000379:methods* / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D015996:Survival Rate