Association between baseline body mass index and the development of fatty liver
| BMI (kg/m2) category | Person-years | Incident case | Age-adjusted HR (95% CI) | Multivariate HR* (95% CI) | HR (95% CI)‡ in the model using time-dependent variables |
| Ultrasonographically detected fatty liver (USFL) | |||||
| <18.5 | 579.7 | 4 | 0.26 (0.10 to 0.71) | 0.32 (0.12 to 0.87) | 0.25 (0.06 to 1.02) |
| 18.5–22.9 | 8746.1 | 241 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 23.0–24.9 | 4807.7 | 222 | 1.65 (1.38 to 1.99) | 1.27 (1.05 to 1.53) | 1.71 (1.39 to 2.10) |
| ⩾25.0 | 2696.3 | 155 | 2.08 (1.70 to 2.54) | 1.37 (1.10 to 1.71) | 1.94 (1.54 to 2.44) |
| p For trend | <0.001 | <0.001 | <0.001 | ||
| USFL + elevated ALT | |||||
| <22.9§ | 9551.0 | 64 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| 23.0–24.9 | 5048.3 | 53 | 1.53 (1.06 to 2.20) | 1.03 (0.71 to 1.51) | 2.12 (1.38 to 3.25) |
| ⩾25.0 | 2860.2 | 42 | 2.15 (1.45 to 3.17) | 1.15 (0.75 to 1.75) | 2.55 (1.60 to 4.04) |
| p For trend | <0.001 | 0.542 | <0.001 |
*Estimated from Cox proportional hazard models adjusted for age, smoking status, HDL-C, triglycerides, ALT, uric acid and HOMA-IR at baseline.
‡Estimated from extended Cox proportional hazard models with BMI as a time-dependent variable adjusted for other covariates (age, smoking status, HDL-C, triglycerides, ALT, uric acid, and HOMA-IR) over time as time-dependent variables.
§The BMI categories of <18.5 and 18.5–22.9 were combined due to the small number of incident cases.
ALT, alanine aminotransferase; BMI, body mass index; CI, confidence intervals; HDL-C, high-density lipoprotein-cholesterol; HOMA-IR, homeostasis model assessment of insulin resistance; HR, hazard ratios.