Table 2.
Subgroup analyses of the association between BMI and delirium incidence
| Variables, n | No of events* |
Healthy weight 18.5≤BMI<25 kg/m² |
Underweight BMI <18.5 kg/m² |
Overweight 25≤BMI<30 kg/m² | Obesity grade 1 30≤BMI<35 kg/m² | Obesity grade 2 35≤BMI<40 kg/m² | Obesity grade 3 BMI ≥40 kg/m² |
P for interaction value | ||||
| Reference group | RR (95% CI) | RR (95% CI) | RR (95% CI) | RR (95% CI) | RR (95% CI) | |||||||
| Age, years | 0.993 | |||||||||||
| ≤65, 9536 | 2679 | 1 | 1.01 (0.90 to 1.13) | 0.96 (0.90 to 1.04) | 0.93 (0.85 to 1.01) | 0.93 (0.83 to 1.05) | 1.03 (0.91 to 1.15) | |||||
| >65, 10 657 | 3543 | 1 | 1.01 (0.92 to 1.11) | 0.94 (0.89 to 1.00) | 0.90 (0.83 to 0.98)* | 1.00 (0.90 to 1.12) | 1.06 (0.93 to 1.21) | |||||
| Gender | 0.773 | |||||||||||
| Male, 11 283 | 3416 | 1 | 1.03 (0.92 to 1.14) | 0.94 (0.89 to 1.00) | 0.87 (0.81 to 0.95)** | 0.94 (0.83 to 1.05) | 1.01 (0.88 to 1.15) | |||||
| Female, 8910 | 2806 | 1 | 0.99 (0.90 to 1.09) | 0.95 (0.88 to 1.02) | 0.93 (0.85 to 1.02) | 0.97 (0.86 to 1.08) | 1.02 (0.91 to 1.14) | |||||
| CHF | 0.463 | |||||||||||
| Yes, 4838 | 1613 | 1 | 0.98 (0.84 to 1.14) | 0.99 (0.91 to 1.09) | 0.98 (0.87 to 1.09) | 1.08 (0.94 to 1.24) | 1.06 (0.91 to 1.24) | |||||
| No, 15 355 | 4609 | 1 | 1.03 (0.95 to 1.11) | 0.94 (0.89 to 0.99)* | 0.88 (0.82 to 0.95)** | 0.91 (0.83 to 1.01) | 1.01 (0.91 to 1.12) | |||||
| Dementia | 0.463 | |||||||||||
| Yes, 596 | 383 | 1 | 1.10 (0.92 to 1.31) | 1.11 (0.96 to 1.27) | 0.98 (0.82 to 1.18) | 1.32 (1.01 to 1.74)* | 1.16 (0.70 to 1.95) | |||||
| No, 19 597 | 5839 | 1 | 1.00 (0.93 to 1.08) | 0.94 (0.90 to 0.99)* | 0.91 (0.85 to 0.96)** | 0.94 (0.87 to 1.02) | 1.01 (0.92 to 1.10) | |||||
| Cerebrovascular disease | 0.099 | |||||||||||
| Yes, 2404 | 945 | 1 | 1.09 (0.91 to 1.30) | 1.06 (0.96 to 1.19) | 0.99 (0.86 to 1.15) | 0.97 (0.79 to .21) | 0.93 (0.71 to 1.22) | |||||
| No, 17 789 | 5277 | 1 | 0.99 (0.92 to 1.07) | 0.92 (0.88 to 0.97)** | 0.89 (0.83 to 0.95)*** | 0.95 (0.87 to 1.03) | 1.02 (0.93 to 1.12) | |||||
| Paraplegia | 0.655 | |||||||||||
| Yes, 617 | 304 | 1 | 0.93 (0.64 to 1.34) | 0.98 (0.82 to 1.17) | 0.99 (0.79 to 1.24) | 0.99 (0.73 to 1.35) | 0.96 (0.64 to 1.43) | |||||
| No, 19 576 | 5918 | 1 | 1.01 (0.94 to 1.08) | 0.94 (0.90 to 0.99)* | 0.90 (0.84 to 0.95)** | 0.96 (0.88 to 1.04) | 1.02 (0.93 to 1.11) | |||||
| Chronic pulmonary disease | 0.069 | |||||||||||
| Yes, 4598 | 1531 | 1 | 1.05 (0.92 to 1.18) | 0.91 (0.83 to 1.01) | 1.00 (0.89 to 1.12) | 1.04 (0.90 to 1.19) | 1.03 (0.88 to 1.21) | |||||
| No, 15 595 | 4691 | 1 | 0.99 (0.91 to 1.08) | 0.95 (0.91 to 1.01) | 0.87 (0.81 to 0.93)*** | 0.92 (0.83 to 1.01) | 1.01 (0.91 to 1.12) | |||||
| Sepsis | 0.007 | |||||||||||
| Yes, 11 007 | 4631 | 1 | 0.97 (0.90 to 1.05) | 0.97 (0.92 to 1.01) | 0.94 (0.88 to 1.00) | 1.01 (0.93 to 1.10) | 1.04 (0.95 to 1.14) | |||||
| No, 9186 | 1591 | 1 | 1.13 (0.96 to 1.34) | 0.94 (0.85 to 1.05) | 0.84 (0.73 to 0.97)** | 0.81 (0.66 to 1.00)* | 0.99 (0.79 to 1.24) | |||||
| SOFA score | 0.118 | |||||||||||
| ≤4, 11 116 | 2197 | 1 | 1.10 (0.97 to 1.25) | 0.96 (0.88 to 1.05) | 0.94 (0.84 to 1.05) | 1.00 (0.86 to 1.16) | 1.13 (0.95 to 1.35) | |||||
| >4, 9077 | 4025 | 1 | 0.96 (0.88 to 1.04) | 0.95 (0.91 to 1.01) | 0.88 (0.82 to 0.94)*** | 0.94 (0.86 to 1.03) | 0.99 (0.90 to 1.09) | |||||
| Invasive ventilation | 0.291 | |||||||||||
| Yes, 6333 | 2843 | 1 | 0.93 (0.85 to 1.03) | 0.92 (0.86 to 0.98) | 0.90 (0.83 to 0.97) | 0.98 (0.88 to 1.09) | 1.03 (0.93 to 1.15) | |||||
| No, 13 860 | 3379 | 1 | 1.05 (0.95 to 1.16) | 0.97 (0.91 to 1.04) | 0.92 (0.84 to 1.00) | 0.94 (0.83 to 1.06) | 1.03 (0.90 to 1.19) | |||||
| Emergency surgery | 0.114 | |||||||||||
| Yes, 15 113 | 4618 | 1 | 0.97 (0.89 to 1.05) | 0.94 (0.89 to 0.99)* | 0.88 (0.82 to 0.94)*** | 0.93 (0.85 to 1.02) | 1.04 (0.94 to 1.14) | |||||
| No, 5080 | 1604 | 1 | 1.11 (0.98 to 1.26) | 0.98 (0.89 to 1.07) | 0.98 (0.87 to 1.10) | 1.02 (0.87 to 1.20) | 0.93 (0.76 to 1.13) | |||||
| GCS | 0.345 | |||||||||||
| GCS >8, 19 064 | 5982 | 1 | 1.02 (0.95 to 1.10) | 0.97 (0.93 to 1.02) | 0.93 (0.87 to 0.98)** | 0.97 (0.89 to 1.06) | 1.02 (0.94 to 1.12) | |||||
| GCS ≤8, 589 | 240 | 1 | 0.83 (0.59 to 1.16) | 0.93 (0.74 to 1.17) | 0.98 (0.76 to 1.26) | 1.29 (0.94 to 1.77) | 1.16 (0.68 to 1.99) | |||||
| Midazolam | 0.068 | |||||||||||
| Yes, 3407 | 1901 | 1 | 1.02 (0.93 to 1.13) | 1.00 (0.93 to 1.07) | 1.02 (0.94 to 1.12) | 1.07 (0.95 to 1.20) | 1.02 (0.90 to 1.14) | |||||
| No, 16 723 | 4321 | 1 | 1.01 (0.92 to 1.11) | 0.94 (0.89 to 1.00)* | 0.88 (0.82 to 0.95)** | 0.93 (0.84 to 1.03) | 1.02 (0.91 to 1.15) | |||||
Subgroup analyses based on model 3.
*P<0.05; **p<0.01; ***p<0.001.
*The number of patients with delirium.
BMI, body mass index; CHF, congestive heart failure; GCS, Glasgow Coma Scale; RR, relative risk; SOFA, Sequential Organ Failure Assessment.