O-8 - China Kadoorie egg intake calibrated to 0.29-0.76 eggs per day across categories
Frequency categories and calibrated mean intake (egg/day): never/rarely 0.29; 1-3 days/month 0.36; 1-3 days/week 0.46; 4-6 days/week 0.56; daily 0.76. Reproducibility of the frequency measure (age/sex-adjusted Spearman r) was 0.58 over a mean 5.4-month interval (n=926). This exposure ceiling means the paper’s dose-response says nothing about intakes above ~1 egg/day.
Link to originalMethodology
Prospective cohort of 512,891 adults aged 30-79 from 10 regions (5 urban, 5 rural) of China, recruited 2004-2008; 461,213 eligible after excluding prior cancer/heart disease/stroke/diabetes and missing BMI. Median follow-up 8.9 y (3.9M person-years to 31 Dec 2015). Egg intake by a laptop-based single-baseline qualitative FFQ (categories never/rarely, 1-3 days/month, 1-3 days/week, 4-6 days/week, daily) covering the prior 12 months; usual amounts calibrated from a 2013-14 resurvey. Outcomes (CVD I00-I99, IHD I20-I25, haemorrhagic stroke I61, ischaemic stroke I63, major coronary events = fatal IHD or non-fatal MI) ascertained via disease/death registries, national health-insurance linkage, and active follow-up. Stratified Cox models (strata: survey site, 5-year birth cohort; attained age as timescale); fully-adjusted Model 3 covariates: age, sex, education, household income, marital status, alcohol, smoking, physical activity, BMI, waist-hip ratio, prevalent hypertension, aspirin use, family CVD history, multivitamin use, dietary pattern. Linear trend by category midpoints. Prespecified stratified analyses by sex, age, area, education, income, alcohol, smoking, physical activity, dietary pattern, BMI, hypertension.
Link to original
Why this is evidence
The salient Asian “inverse” (China Kadoorie) is measured entirely below ~1 egg/day (top category 0.76/day). H-50’s differential-exposure-range explanation needs precisely this: the protective Asian signal sits on the low-intake limb of the dose-response. H-22 and H-7 do not specifically predict that the Asian cohorts cluster at a narrow low intake range.
Likelihood
# E-128 (HC-2) — lone edge, one observation O-8 "China Kadoorie egg intake (single non-validated FFQ,
# calibrated) spans only 0.29-0.76 egg/day — the salient Asian inverse is measured entirely below ~1
# egg/day." Members in HC-2.hypotheses order [H-7, H-22, H-50]. No edge arguments. Anchored on H-50 = 1
# (best fit); others as ratios (rule 7).
lik_o8_H50 = 1.0 # anchor: H-50's exposure-range explanation needs exactly this — the salient Asian inverse
# sitting on the low-intake limb of one dose-response, reframing "inverse in Asia" as
# inverse-at-low-intake (dose-position)
lik_o8_H22 = 0.6 # 0.6×: genuine region-modification neither needs nor predicts the Asian cohort clustering
# at a narrow low intake; the low ceiling conflates region with dose-position, mildly
# against a clean regional-causal reading. Not lower because low Asian egg intake is a
# real-world fact roughly independent of which member holds
lik_o8_H7 = 0.65 # 0.65×: healthy-user/residual confounding likewise does not specifically predict the low
# intake range — roughly neutral; a touch above H-22 because the single non-validated FFQ
# (reproducibility r=0.58) noted here fits a confounding/measurement-artefact framing
# marginally better than genuine modification
t_o8 = 0.6 # cap = trust_score of O-8's source S-80 = 0.6 (already low; the non-validated crude FFQ is
# why it is low). The exposure-range datum rests on the 2013-14 resurvey calibration and is
# solid for its purpose; kept at cap (rule 4)
evidence("HC-2", ["O-8"], [lik_o8_H7, lik_o8_H22, lik_o8_H50], t=t_o8)