Table 4.
Additive interaction between quartiles of fast-food outlet proportion and household income on the odds of being obese (BMI ≥ 30 kg/m2), modelled using a binomial logistic regression model in the UK Biobank sample, UK (n = 51,361)
| Quartiles of fast-food outlet proportiona | Fast-food outlet exposure (Q4) within household income strata | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Q1 (0–13%) | Q2 (13–17%) | Q3 (17–24%) | Q4 (24–45%) | ||||||
| Household Income (£/year) | Obese/not obese (n) | OR (95% CI) | Obese/not obese (n) | OR (95% CI) | Obese/not obese (n) | OR (95% CI) | Obese/not obese (n) | OR (95% CI) | |
| > 100,000 | 264/2145 | refb | 206/1298 | 1.30 (1.07, 1.59); P = 0.008c |
143/733 | 1.60 (1.27, 2.00); P < 0.001c |
104/487 | 1.73 (1.34, 2.23); P < 0.001c |
1.53 (1.12, 2.08) P = 0.008d |
| 52,000–100,000 | 433/2624 | 1.27 (1.08, 1.50); P = 0.004c |
475/2559 | 1.44 (1.22, 1.69); P < 0.001c |
494/2069 | 1.81 (1.53, 2.13); P < 0.001c |
581/1834 | 2.26 (1.91, 2.66); P < 0.001c |
1.69 (1.43, 2.02) P < 0.001d |
| 31,000–51,999 | 389/2007 | 1.42 (1.20, 1.69); P < 0.001c |
495/2162 | 1.64 (1.39, 1.93); P < 0.001c |
605/2151 | 1.95 (1.66, 2.29); P < 0.001c |
724/2157 | 2.20 (1.87, 2.58); P < 0.001c |
1.51 (1.27, 1.80) P < 0.001d |
| < 31,000 | 687/26922 | 1.67 (1.43, 1.95); P < 0.001c |
957/2902 | 2.05 (1.76, 2.39); P < 0.001c |
1271/3292 | 2.30 (1.98, 2.68); P < 0.001c |
1401/3397 | 2.43 (2.09, 2.84); P < 0.001c |
1.56 (1.37, 1.78) P < 0.001d |
| Household income (< £31,000/year) within takeaway exposure strata | 1.58 (1.34, 1.88) P < 0.001e |
1.36 (1.15, 1.65) P = 0.001e |
1.49 (1.21, 1.82) P < 0.001e |
1.53 (1.22, 1.93) P < 0.001e |
|||||
Measure of interaction (fast-food exposure*household income with odds of obesity) on a multiplicative scale based on a likelihood ratio test, P = 0.054 | Measure of interaction on an additive scale for Q4 fast-food exposure and household income < £31,000 (RERI) = 0.03. RERI scores > 0 suggest positive interaction and departure from additivity | ORs are adjusted for age, sex, ethnicity smoking status, number in household, highest education attainment, UK Biobank assessment centre attended, and the sum of counts of Supermarkets, Restaurants, Convenience stores, Cafes and Specialist Stores within 1 mile Euclidean (straight line) radius buffers of home address | a Q1 = quartile with lowest fast-food outlet proportion in home neighbourhood (min – max %) – Q4 = quartile with greatest fast-food outlet proportion in home neighbourhood (% range) | b Single reference group; those exposed to the highest proportion of fast-food outlets and with the highest household income | c ORs and p values relative to single reference group (ref) | d ORs and P values relative to those who were least exposed to fast-food outlets within strata of household income | e ORs and P values relative to those with the highest household incomes within strata of fast-food outlet exposure