Measuring Height without a Stadiometer: Empirical Investigation of Four Height Estimates Among Wheelchair Users

Obtaining an accurate height estimate is important for calculating body mass index [BMI], 1-3 pulmonary function, 4 determining body surface area for drug dosages and renal clearances, and other patient care issues.1 However, measuring height can be difficult for individuals who cannot stand,2,5 or who have various physical anomalies such as spasticity, 6 contractures, fractures, amputations, scoliosis, paralysis,1 or osteoporosis.7 Unfortunately, there is no criterion standard to measure or estimate height for those who cannot stand to be measured with a stadiometer. Lack of a standardized approach for those who cannot stand limits data availability and quality for this population. For example, without guidelines recommending how to measure height for those unable to stand, the federal initiative designed to assess the health and nutritional status of Americans, the National Health and Nutrition Examination Survey (NHANES), has forgone collecting height data for those unable to stand unassisted. Therefore, NHANES data which are used to calculate BMI and track obesity prevalence are not available for those with mobility impairments that affect walking or standing. Individuals with serious mobility impairment that precludes standing are not the only group for whom standing height measures are difficult to obtain. Standing height is also difficult to obtain among older adults with kyphosis and hospitalized, bedridden patients. Investigators have assessed the validity of armspan,8-10 demi-span,11 half-armspan, and knee height12,13 among others for use as potential height estimates for use in these groups in lieu of standing height. Several published studies have explored alternate methods for measuring or estimating stature among this population.14,15 Using a similar approach to the one created to predict stature among older adults, Chumlea et al.15 used knee height to predict stature among children and adults with mobility impairments based on data from the National Health and Nutrition Examination Survey (NHES, 1960-1970). Although these equations derive from non-impaired populations, the authors suggest the estimates can be applied to a mobility impaired sample. More recently, Canda14 explored which of several estimation equations best predicted stature for mobility impaired individuals, but also collected data from a non-impaired sample. Estimation equations were derived from eight anthropometric indices: sitting height, armspan, upper arm length, forearm length, hand length, thigh length, lower leg length, and foot length. The authors report that the equations that include sitting height and upper and lower extremities yielded the highest correlations with the lowest errors, although the specific measures included in equations differed by sex. Thus, the authors suggest obtaining multiple measures for use in an equation to derive the best height estimate. Garshick et al.4 examined the accuracy of self-report and whether upper extremity measures predicted stature in those with spinal cord injury (SCI) compared to recumbent length. Although upper extremity measures significantly predicted measured body length, self-reported height accounted for greater variance in measured length than any upper extremity measures, including armspan. Nevertheless, men with SCI overestimated their height by an average of 2.3 cm ± 3.45 cm. Finally, results from several studies support measuring upper arm length or knee height as alternate approaches for estimating height among children and adults with cerebral palsy.6,16,17 Despite the array of available height measurement and estimation methods, there is a need to investigate which of several approaches is most accurate for determining height among those who cannot stand. Therefore, the purpose of this study was to determine 1) if various methods for measuring height yield significantly different height estimates among wheelchair users with diverse impairments and 2) which method yields the most accurate height estimate for this population. Height assessment methods examined included (a) self-report; (b) recumbent length, (c) armspan length and (d) estimate from knee height using a formula developed for individuals with mobility impairment.15