Accuracy of the Electronic Health Record: Patient Height

Protective lung ventilation requires calculating predicted body weight (BW) from height. Thus, inaccuracy of height data in the electronic health record (EHR) is a risk factor for ventilator-induced lung injury. Charted height data often have uncertain accuracy. Study purposes were (1) to evaluate the difference between patient height charted in the EHR and predicted height (PH) from ulnar length and (2) to determine how the height data source affects predicted BW and the resulting values for protective tidal volume (V(T)).

Subject height data from the EHR were collected from several ICUs. Simultaneous ulnar data were collected by measuring ulnar length (cm): male PH (cm) = 79.2 ± 3.60 × ulnar length; female PH = 95.6 ± 2.77 × ulnar length. For each subject, BW (kg) was calculated from height charted in EHR and from predicted height: male BW = 50 ± 0.91 × (height - 152.4); female BW = 45.5 ± 0.91 × (height - 152.4). Then V(T) was calculated as 8 mL/kg BW. Bland-Altman analysis of height and V(T) differences (charted - predicted) determined the limits of agreement.

For white males (n = 27) the mean (SD) height from EHR was 177 (7.5); predicted height was 178 (6.9). The limits of agreement for height in males were -18.5 and 17.8 cm. The limits of agreement for females were -23.1 and 21.3 cm. The limits of agreement for V(T) in males were -1.8 and 1.8 mL/kg. The limits of agreement for V(T) in females were -3.0 and 2.9 mL/kg.

For overall populations, mean height calculated from values charted in the EHR is similar to that estimated from ulnar length. However, for individuals, differences in height between the 2 sources can be large, leading to large differences in predicted BW and resultant V(T) set in terms of mL/kg.