Research Article
Low, rather than High, Body Mass Index Is a Risk Factor for Acute Kidney Injury in Multiethnic Asian Patients: A Retrospective Observational Study
Table 1
Baseline characteristics in relation to body mass index categories according to the World Health Organisation (WHO) classification on Asians.
| | | BMI, kg/m2 | | Total | <18.5 | 18.5–23 | 23–27.5 | >27.5 |
| | Number of patients | 12555 | 1727 | 4339 | 3902 | 2587 | | Demographics | | | | | | | Age, year | | | | | | | Gender, men (%) | 6755 (53.8) | 856 (49.6) | 2329 (53.7) | 2264 (58.0) | 1306 (50.5) | | Ethnicity () | | | | | | | Chinese | 7776 (61.9) | 1257 (72.8) | 2942 (67.8) | 2424 (62.1) | 1153 (44.6) | | Malay | 2360 (18.8) | 230 (13.3) | 626 (14.4) | 721 (18.5) | 783 (30.3) | | Indian | 1485 (11.8) | 146 (8.5) | 458 (10.6) | 460 (11.8) | 421 (16.3) | | Others | 934 (7.4) | 94 (5.4) | 313 (7.2) | 297 (7.6) | 230 (8.9) | | Specialty () | | | | | | | Medicine | 6353 (50.6) | 871 (50.4) | 2175 (50.2) | 1977 (50.1) | 1330 (51.4) | | Surgery | 1679 (13.4) | 173 (10.0) | 631 (14.5) | 548 (14.0) | 327 (12.6) | | Geriatrics | 1591 (12.7) | 427 (24.7) | 637 (14.7) | 399 (10.2) | 128 (4.9) | | Cardiology | 1479 (11.8) | 111 (6.4) | 417 (9.6) | 503 (12.9) | 448 (17.3) | | Orthopedic surgery | 1147 (9.1) | 121 (7.0) | 391 (9.0) | 360 (9.3) | 275 (10.6) | | Urology | 248 (2.0) | 17 (1.0) | 73 (1.7) | 94 (2.4) | 64 (2.4) | | Otolaryngology | 41 (0.3) | 5 (0.3) | 9 (0.2) | 14 (0.4) | 13 (0.5) | | Ophthalmology | 17 (0.1) | 2 (0.1) | 6 (0.1) | 7 (0.2) | 2 (0.1) | | Background diagnosis () | | | | | | | Hypertension | 4895 (39.0) | 653 (37.8) | 1579 (36.4) | 1519 (38.9) | 1144 (44.2) | | Dyslipidemia | 3896 (31.0) | 435 (25.2) | 1229 (28.3) | 1271 (32.6) | 961 (37.1) | | Diabetes mellitus | 3289 (26.2) | 341 (19.7) | 1039 (23.9) | 1072 (27.5) | 837 (32.4) | | Cardiovascular disease | 2515 (20.0) | 349 (20.2) | 878 (20.2) | 771 (19.8) | 517 (20.0) | | Orthopedic related disease | 1402 (11.2) | 262 (15.2) | 470 (10.8) | 397 (10.2) | 273 (10.6) | | Cerebrovascular disease | 1314 (10.5) | 256 (14.8) | 485 (11.2) | 392 (10.0) | 181 (7.0) | | Neurological disease | 1219 (9.7) | 283 (16.4) | 496 (11.4) | 307 (7.9) | 133 (5.1) | | Respiratory disease | 1030 (8.2) | 199 (11.5) | 292 (6.7) | 257 (6.6) | 282 (10.9) | | Hematological disease | 955 (7.6) | 230 (13.3) | 380 (8.8) | 226 (5.8) | 119 (4.6) | | Gastrointestinal disease | 936 (7.5) | 221 (12.2) | 324 (7.5) | 243 (6.2) | 158 (6.1) | | Chronic kidney disease | 857 (6.8) | 111 (6.4) | 270 (6.2) | 286 (7.3) | 190 (7.3) | | Psychiatric illness | 760 (6.1) | 172 (10.0) | 290 (6.7) | 205 (5.3) | 93 (3.6) | | Urological disease | 595 (4.7) | 120 (6.9) | 238 (5.5) | 157 (4.0) | 80 (3.1) | | Underlying malignancy | 584 (4.7) | 140 (8.1) | 234 (5.4) | 148 (3.8) | 62 (2.4) | | Hepatobiliary disease | 463 (3.7) | 64 (3.7) | 155 (3.6) | 147 (3.8) | 97 (3.7) | | Procedures () | | | | | | | Endoscopy | 2355 (18.8) | 363 (21.0) | 853 (19.7) | 673 (17.2) | 466 (18.0) | | Orthopedic surgery | 1222 (9.7) | 170 (9.8) | 413 (9.5) | 368 (9.4) | 271 (10.5) | | Cardiology related procedures (non-open-heart surgery) | 584 (4.7) | 32 (1.9) | 156 (3.6) | 219 (5.6) | 177 (6.8) | | Excision of skin lesions | 851 (6.8) | 64 (3.7) | 259 (6.0) | 195 (7.6) | 233 (9.0) | | Open laparotomy | 579 (4.6) | 77 (4.5) | 231 (5.3) | 182 (4.7) | 89 (3.4) | | Urology related surgery | 510 (4.1) | 61 (3.5) | 169 (3.9) | 161 (4.1) | 119 (4.6) | | Laparoscopic surgery (intra-abdominal) | 265 (2.1) | 23 (1.3) | 85 (2.0) | 81 (2.1) | 75 (2.9) | | Neurosurgery | 159 (1.3) | 19 (1.1) | 68 (1.6) | 50 (1.3) | 22 (0.9) | | Otolaryngology related surgery | 149 (1.2) | 26 (1.5) | 55 (1.3) | 33 (0.8) | 35 (1.4) | | Vascular surgery, open | 57 (0.5) | 8 (0.5) | 15 (0.3) | 25 (0.6) | 9 (0.3) | | Laparoscopic assisted bariatric bypass surgery | 12 (0.18) | 0 (0) | 0 (0) | 5 (0.1) | 7 (0.3) | | Hospitalisation characteristics | | | | | | | ICU admission (%) | 1638 (13.0) | 155 (9.0) | 490 (11.3) | 571 (14.7) | 421 (16.3) | | Mortality within 90 days of admission (%) | 997 (7.9) | 256 (14.8) | 414 (9.5) | 239 (6.1) | 88 (3.4) | | Length of stay (d, IQR) | 5 (3–9) | 7 (4–14) | 5 (3–10) | 4 (3–8) | 4 (2–7) | | Creatinine measurements | | | | | | | Time from baseline measurement to hospitalisation (d, IQR) | 71 (29–147) | 62 (30–140) | 69 (28–140.8) | 69 (26–148.8) | 79 (32–159) | | Number of measurements within 365 days before hospitalisation (, IQR) | 4 (2–6) | 4 (3–6) | 4 (2–6) | 4 (2–7) | 2 (2–6) |
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AKI: acute kidney injury; ICU: intensive care unit; BMI: body mass index; IQR: interquartile range.
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