Table 5.
Associations between changing slope in body mass index and clinical outcomes: subgroup analysis
| Overall survival | Breast cancer-specific survival | Disease-free survival | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Events/persons | HR (95% CI)* | P | Events/persons | HR (95% CI)* | P | Events/persons | HR (95% CI)* | P | |
| In Whites | |||||||||
| Loss > 0.5 kg/m2/year | 40/285 | 2.22 (1.31–3.75) | 0.003 | 20/285 | 1.75 (0.86–3.55) | 0.12 | 40/266 | 2.04 (1.21–3.44) | 0.008 |
| Stable (≤ 0.5 kg/m2/year) | 30/744 | 1.0 (ref.) | 18/744 | 1.0 (ref.) | 31/706 | 1.0 (ref.) | |||
| Gain > 0.5 kg/m2/year | 25/372 | 1.41 (0.79–2.51) | 0.25 | 15/372 | 1.02 (0.47–2.19) | 0.96 | 22/348 | 1.33 (0.75–2.38) | 0.33 |
| In Blacks | |||||||||
| Loss > 0.5 kg/m2/year | 93/280 | 2.80 (1.86–4.22) | < 0.001 | 46/280 | 4.27 (2.22–8.21) | < 0.001 | 83/254 | 2.29 (1.50–3.49) | < 0.001 |
| Stable (≤ 0.5 kg/m2/year) | 42/437 | 1.0 (ref.) | 14/437 | 1.0 (ref.) | 46/409 | 1.0 (ref.) | |||
| Gain > 0.5 kg/m2/year | 36/219 | 1.72 (1.05–2.84) | 0.033 | 23/219 | 2.48 (1.21–5.08) | 0.013 | 37/205 | 1.78 (1.08–2.92) | 0.023 |
| Test for interaction | 0.77 | 0.14 | 0.76 | ||||||
| In women with normal weight at diagnosis | |||||||||
| Loss > 0.5 kg/m2/year | 15/77 | 1.92 (0.91–4.05) | 0.086 | 8/77 | 2.73 (0.90–8.31) | 0.077 | 15/74 | 1.91 (0.87–4.16) | 0.11 |
| Stable (≤ 0.5 kg/m2/year) | 22/445 | 1.0 (ref.) | 10/445 | 1.0 (ref.) | 18/427 | 1.0 (ref.) | |||
| Gain > 0.5 kg/m2/year | 10/182 | 0.99 (0.45–2.16) | 0.97 | 6/182 | 1.33 (0.44–4.03) | 0.61 | 11/176 | 1.16 (0.53–2.55) | 0.71 |
| In women with overweight/obese at diagnosis | |||||||||
| Loss > 0.5 kg/m2/year | 85/414 | 3.07 (1.96–4.80) | < 0.001 | 46/414 | 3.08 (1.62–5.87) | 0.001 | 76/389 | 2.21 (1.41–3.45) | < 0.001 |
| Stable (≤ 0.5 kg/m2/year) | 36/647 | 1.0 (ref.) | 16/647 | 1.0 (ref.) | 44/613 | 1.0 (ref.) | |||
| Gain > 0.5 kg/m2/year | 30/318 | 1.96 (1.14–3.37) | 0.015 | 16/318 | 1.47 (0.69–3.12) | 0.32 | 27/304 | 1.56 (0.90–2.71) | 0.11 |
| Test for interaction | 0.32 | 0.98 | 0.83 | ||||||
| In women ages < 50 | |||||||||
| Loss > 0.5 kg/m2/year | 24/135 | 3.94 (1.87–8.30) | < 0.001 | 17/135 | 3.40 (1.40–8.25) | 0.007 | 21/115 | 4.48 (2.05–9.79) | < 0.001 |
| Stable (≤ 0.5 kg/m2/year) | 13/407 | 1.0 (ref.) | 10/407 | 1.0 (ref.) | 11/372 | 1.0 (ref.) | |||
| Gain > 0.5 kg/m2/year | 18/281 | 1.58 (0.74–3.39) | 0.238 | 16/281 | 1.64 (0.69–3.90) | 0.27 | 16/259 | 1.65 (0.74–3.67) | 0.22 |
| In women ages ≥ 50 | |||||||||
| Loss > 0.5 kg/m2/year | 113/467 | 2.38 (1.67–3.38) | < 0.001 | 52/467 | 2.95 (1.73–5.04) | < 0.001 | 104/439 | 1.83 (1.28–2.62) | 0.001 |
| Stable (≤ 0.5 kg/m2/year) | 63/882 | 1.0 (ref.) | 25/882 | 1.0 (ref.) | 70/845 | 1.0 (ref.) | |||
| Gain > 0.5 kg/m2/year | 45/350 | 1.68 (1.09–2.59) | 0.019 | 24/350 | 1.83 (0.98–3.43) | 0.057 | 45/333 | 1.59 (1.04–2.43) | 0.032 |
| Test for interaction | 0.26 | 0.86 | 0.043 | ||||||
*Adjusted for age, race, Carlson comorbidity index, tumor stage, histologic grade, molecular subtype, radiotherapy, hormonal therapy, and chemotherapy in delayed entry Cox models
Abbreviations: BMI body mass index, HR hazard ratio, CI confidence intervals