Also known as IBW, Adjusted Body Weight, AdjBW, ABW, Devine
Devine ideal body weight and adjusted body weight, in kg.
Applies to / doesn’t apply to1
Applies to: Adults. The equations are written from a standing height of 5 ft (152.4 cm); shorter heights are accepted with a warning. The equations were published in a 1974 clinical-pharmacy case discussion of gentamicin therapy (McCarron & Devine 1974) and match an older rule drawn from insurance height–weight tables (Pai 2000).
- Children: the equations come from adult height–weight tables and have no paediatric form.
Selects the Devine equation: base weight 50 kg for male, 45.5 kg for female. The source defines no rule beyond these two.
Measured standing height. The equations start at 5 ft (152.4 cm); below that they are extended and the result carries a warning.
Current measured weight. Needed only for adjusted body weight, which is shown when actual weight is at or above ideal body weight.
What this score estimates
Ideal body weight by the Devine equations: 50 kg for men or 45.5 kg for women at 5 ft, plus 2.3 kg for each inch over 5 ft. Below 5 ft the same line is extended (2.3 kg less for each inch under) and the result carries a warning. When actual body weight is entered and is at or above ideal body weight, adjusted body weight is shown beside it: ideal body weight plus 0.4 times the difference. Reported in kg to one decimal.
Pearls & pitfalls
11
- Below 5 ft (152.4 cm) the Devine equations are extended in a straight line, 2.3 kg less for each inch under 5 ft, as MDCalc does. No published source validates them there, so a warning is shown with the result.
- The Devine equations were published in a gentamicin case discussion without reference to a dataset; they agree with older rules derived from insurance height–weight tables, which is why the several ideal-body-weight equations give similar results (Pai 2000).
- Ideal body weight is a height-and-sex convention, not a measurement of lean body mass, though it has often been used as a stand-in for one (Pai 2000).
- The 0.4 factor comes from aminoglycoside studies in obese patients. The earliest primary source found used normalized body mass plus 40% of adipose mass in 13 obese subjects (Schwartz 1978); a 1,708-patient cohort derived 0.43 instead (Traynor 1995).
- The factor is not universal: about 0.3 has been proposed for hydrophilic antibiotics generally and about 0.45 for quinolones (Wurtz 1997).
- In 2,073 aminoglycoside-treated adults, only lean body weight (Janmahasatian method) normalised the volume of distribution across every weight class (Pai 2011).
- For the Cockcroft–Gault equation, adjusted body weight with a 0.4 factor was the least biased and most accurate weight in overweight, obese and morbidly obese patients in a single-centre retrospective study of 3,678 patients (Winter 2012).
- Adjusted body weight is not shown when actual weight is below ideal body weight: every source that derived the factor studied patients above it, and Traynor 1995 gives a different equation for underweight patients.
Risk factors the score does not count:
- Body composition: muscle mass, oedema and ascites change actual weight without changing the ideal-body-weight result.
- Amputation: the equations have no adjustment for limb loss.
- Age and frame size.
Where this comes from
7
References
- McCarron MM, Devine BJ. Clinical Pharmacy: Case Studies — Case Number 25: Gentamicin therapy. Drug Intell Clin Pharm. 1974;8(11):650-655. View source ↗
- Pai MP, Paloucek FP. The origin of the "ideal" body weight equations. Ann Pharmacother. 2000;34(9):1066-9. View source ↗
- Schwartz SN, Pazin GJ, Lyon JA, Ho M, Pasculle AW. A controlled investigation of the pharmacokinetics of gentamicin and tobramycin in obese subjects. J Infect Dis. 1978;138(4):499-505. View source ↗
- Traynor AM, Nafziger AN, Bertino JS Jr. Aminoglycoside dosing weight correction factors for patients of various body sizes. Antimicrob Agents Chemother. 1995;39(2):545-8. View source ↗
- Wurtz R, Itokazu G, Rodvold K. Antimicrobial dosing in obese patients. Clin Infect Dis. 1997;25(1):112-8. View source ↗
- Pai MP, Nafziger AN, Bertino JS Jr. Simplified estimation of aminoglycoside pharmacokinetics in underweight and obese adult patients. Antimicrob Agents Chemother. 2011;55(9):4006-11. View source ↗
- Winter MA, Guhr KN, Berg GM. Pharmacotherapy. 2012;32(7):604-12. View source ↗