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. 2014 Jul 16;100(3):959–967. doi: 10.3945/ajcn.114.086918

TABLE 3.

HRs (95% CIs) for incident RA according to cumulative diet soda consumption in the NHS (1980–2008) and the NHS II (1991–2009)1

Diet soda consumption
<1 serving/mo 1–4 servings/mo 2–6 servings/wk ≥1 servings/d P-trend2
All RA
 NHS
 No. of cases/person-years 185/641,158 70/232,725 216/670,981 88/315,326
 Age-adjusted model 1 (Reference) 1.05 (0.80, 1.39) 1.10 (0.90, 1.35) 0.98 (0.75, 1.26) 0.78
 Multivariable-adjusted model3 1 (Reference) 1.02 (0.77, 1.35) 1.02 (0.83, 1.26) 0.87 (0.66, 1.13) 0.24
 NHS II
 No. of cases/person-years 96/496,498 17/116,205 89/464,631 96/443,760
 Age-adjusted model 1 (Reference) 0.72 (0.43, 1.21) 0.92 (0.69, 1.23) 1.09 (0.82, 1.44) 0.27
 Multivariable-adjusted model3 1 (Reference) 0.79 (0.46, 1.34) 0.96 (0.70, 1.31) 1.03 (0.75, 1.41) 0.57
 NHS and NHS II pooled4
 Age-adjusted model 1 (Reference) 0.97 (0.76, 1.23) 1.04 (0.88, 1.23) 1.02 (0.85, 1.24) 0.52
 Multivariable-adjusted model3 1 (Reference) 0.96 (0.75, 1.23) 1.00 (0.84, 1.19) 0.93 (0.76, 1.14) 0.71
Seropositive RA
 NHS
 No. of cases/person-years 125/600,741 39/219,366 133/631,367 52/295,609
 Age-adjusted model 1 (Reference) 0.87 (0.61, 1.25) 1.00 (0.78, 1.28) 0.85 (0.61, 1.18) 0.42
 Multivariable adjusted model3 1 (Reference) 0.84 (0.58, 1.21) 0.93 (0.71, 1.20) 0.75 (0.53, 1.05) 0.14
 NHS II
 No. of cases/person-years 62/486,459 10/114,690 63/457,377 59/434,053
 Age-adjusted model 1 (Reference) 0.64 (0.33, 1.25) 0.98 (0.68, 1.39) 1.04 (0.73, 1.49) 0.54
 Multivariable-adjusted model3 1 (Reference) 0.70 (0.35, 1.38) 1.03 (0.70, 1.51) 0.99 (0.67, 1.46) 0.87
 NHS and NHS II pooled4
 Age-adjusted model 1 (Reference) 0.81 (0.59, 1.12) 0.99 (0.81, 1.21) 0.93 (0.73, 1.19) 0.95
 Multivariable-adjusted model3 1 (Reference) 0.81 (0.58, 1.11) 0.96 (0.77, 1.19) 0.84 (0.65, 1.09) 0.38
Seronegative RA
 NHS
 No. of cases/person-years 60/639,122 31/232,061 83/668,876 36/314,328
 Age-adjusted model 1 (Reference) 1.42 (0.92, 2.21) 1.34 (0.96, 1.89) 1.26 (0.83, 1.91) 0.51
 Multivariable-adjusted model3 1 (Reference) 1.39 (0.89, 2.17) 1.23 (0.87, 1.75) 1.11 (0.72, 1.71) 0.99
 NHS II
 No. of cases/person-years 34/495,617 7/116,014 26/463,798 37/442,836
 Age-adjusted model 1 (Reference) 0.88 (0.39, 2.00) 0.80 (0.48, 1.34) 1.17 (0.73, 1.86) 0.30
 Multivariable-adjusted model3 1 (Reference) 0.97 (0.42, 2.25) 0.84 (0.48, 1.46) 1.12 (0.67, 1.88) 0.45
 NHS and NHS II pooled4
 Age-adjusted model 1 (Reference) 1.28 (0.87, 1.88) 1.15 (0.87, 1.53) 1.22 (0.89, 1.66) 0.23
 Multivariable-adjusted model3 1 (Reference) 1.29 (0.87, 1.90) 1.10 (0.82, 1.48) 1.11 (0.80, 1.55) 0.58
1

1HRs were calculated by using time-varying Cox proportional hazards models. Diet soda included low-calorie cola, low-calorie caffeine-free cola, and other low-calorie carbonated beverages. NHS, Nurses’ Health Study; RA, rheumatoid arthritis.

2

2P values for trend were derived from tests of linear trend across categories of soda consumption by treating the median value of each category as a continuous variable.

3

3Adjusted for age, census tract median family income (quartiles), cigarette smoking status (never; past; current, 1–14 cigarettes/d; or current, ≥15 cigarettes/d), alcohol consumption (<5.0, 5.0–15.0, or >15 g/d), age at menarche (<12, 12, or >12 y), parity and breastfeeding (nulliparous, parous/no breastfeeding, parous/1–12 mo breastfeeding, or parous/>12 mo breastfeeding), hormone use (premenopausal, postmenopausal with never use, current use, or past use), physical activity (0–2.9, 3–8.9, 9–17.9, 18–26.9, or ≥27 metabolic equivalent task-hours/wk), BMI (in kg/m2; <20, 20–22.9, 23–24.9, 25–29.9, or ≥30), multivitamin use, Alternate Healthy Eating Index (quintiles), diabetes history, and total energy (kcal, quintiles).

4

4The results from 2 cohorts were pooled by using an inverse-variance–weighted, fixed-effects meta-analysis.