Table 2.
Summary of mediation analysis: long-term LTPA patterns, BMI, and risk for endometrial cancer
| Effect | Long-term LTPA patternsa |
||||
|---|---|---|---|---|---|
| Inactive | Maintain low | Maintain high | Increasers | Decreasers | |
| (n = 5561) | (n = 11 125) | (n = 21 843) | (n = 13 469) | (n = 15 707) | |
| Endometrial cancers, No. (%) | 149 (2.7) | 245 (2.2) | 439 (2.0) | 259 (1.9) | 376 (2.4) |
| Total effectb, HR (95% CI)c | Referent | 0.84 (0.66 to 1.12) | 0.80 (0.68 to 0.95) | 0.73 (0.59 to 0.94) | 0.98 (0.83 to 1.17) |
| Indirect effect (through midlife BMI), HR (95% CI)c | Referent | 0.97 (0.93 to 1.01) | 0.87 (0.84 to 0.90) | 0.84 (0.81 to 0.89) | 0.98 (0.83 to 1.17) |
| Direct effect, HR (95% CI)c | Referent | 0.87 (0.71 to 1.13) | 0.92 (0.79 to 1.09) | 0.87 (0.70 to 1.11) | 0.92 (0.77 to 1.08) |
| Proportion of LTPA through BMI at midlife, % (95% CI) | Referent | NE | 62.7 (30.6 to 100.0) | 55.5 (31.4 to 100.0) | NE |
Participants with little or no physical activity (<1 h/wk) at each age period were classified as Inactive; those maintaining low levels of activity over time were classified as maintaining low activity; those maintaining high levels of activity over time were classified as maintaining high activity; those that increased their activity over time were classified as increasers; and those that decreased their activity over time were classified as decreasers. BMI = body mass index; CI = confidence intervals; HR = hazard ratio; LTPA = leisure time physical activity; NE = not estimated (ie, the denominator for the proportion was approximately 0 and the estimation was not stable).
The total effect presented in this table can differ from the effects provided in Figure 2 by a residual amount.
Hazard ratios were adjusted for: age (years), race-ethnicity (non-Hispanic white, non-Hispanic Black, Hispanic, other, or missing), education (less than high school, high school, post high-school or some college, bachelor degree or more, missing), smoking status/dose (never smoker, former smoker and ≤20 cigarettes/day, former smoker and >20 cigarettes/day, current smoker and ≤20 cigarettes/day, current smoker and >20 cigarettes/day, missing), diet quality (2015 Healthy Eating Index; 0-100 points), total energy intake (kcal/day), alcohol consumption (grams/day), parity (number of births), use of oral contraceptives (never or <1 year, 1-4 years, 5-9 years, ≥10 years, missing), menopausal hormone therapy use (never, continuous estrogen plus progestin [EPT] use [15+ days progestin/month], sequential EPT [<15 days progestin/month], estrogen only, missing) and, BMI at age 18 years (normal weight [<25.0 kg/m2], overweight [25.0-29.9 kg/m2], obese class I [30.0-34.9 kg/m2], obese class II [35.0-39.9 kg/m2], and obese class III [≥40.0 kg/m2]). Models also included BMI in midlife (normal weight [<25.0 kg/m2], overweight [25.0-29.9 kg/m2], obese class I [30.0-34.9 kg/m2], obese class II [35.0-39.9 kg/m2], and obese class III [≥40.0 kg/m2]) as a mediator of the LTPA-endometrial cancer association.