Validation of a New Method Developed to Measure the Height of Adult Patients in Bed

Abstract

We present the performance of a new instrument developed to measure the height of patients in bed (Luft Ruler). Standing height was the gold standard measured in 116 hospitalized adults with a stadiometer, compared with measurements from the Luft Ruler and calculated estimates. Using the Luft Ruler in women, men, <60 years old, and >60 years old, the mean difference from the gold standard was, respectively, 1.5 cm (P= .02), 1.3 cm (P= .06), 1.2 cm (P= .07), and 1.6 cm (P= .02); total arm span: 6.7 cm, 7.7 cm, 5.4 cm, and 9.0 cm (P< .01 for all strata); 2x half arm span: 7.8 cm, 10.2 cm, 7.7 cm, and 10.3 cm (P< .01 for all); World Health Organization (WHO) equation: 5.5 cm, 6.2 cm, 4.7 cm, and 6.9 cm (P< .01 for all); and the Hospital de Clínicas de Porto Alegre equation: 1.9 cm (P< .01), 2.5 cm (P< .01), 1.1 cm (P= .12), and 3.3 cm (P< .01). The proportion of differences >5 cm was 0.9% (n=1) using the Luft Ruler, 62.9% using total arm span, 71.6% using 2x half arm span, 64.7% using the WHO equation, and 27.6% using the Hospital de Clínicas de Porto Alegre equation. The Luft Ruler was the only method that presented minor mean differences in relation to the gold standard in both gender and age strata. The other estimates are not recommended because of high frequency of relevant errors.