Comparison of bias resulting from two methods of self-reporting height and weight: a validation study

Abstract

ObjectivesTo contrast the validity of two modes of self-reported height and weight data.DesignSubjects’ self-reported height and weight by mailed survey without expectation of subsequent measurement. Subjects were later offered a physical exam, where they self-reported their height and weight again, just prior to measurement. Regression equations to predict actual from self-reported body mass index (BMI) were fitted for both sets of self-reported values. Residual analyses assessed bias resulting from application of each regression equation to the alternative mode of self-report. Analyses were stratified by gender.SettingUpstate New York.ParticipantsSubjects (n = 260) with survey, pre-exam and measured BMI.Main outcome measuresPrevalence of obesity based on two modes of self-report and also measured values. Bias resulting from misapplication of correction equations.ResultsAccurate prediction of measured BMI was possible for both self-report modes for men (R 2 = 0.89 survey, 0.85 pre-exam) and women (R 2 = 0.92 survey, 0.97 pre-exam). Underreporting of BMI was greater for survey than pre-exam but only significantly so in women. Obesity prevalence was significantly underestimated by 10.9% (p < 0.001) and 14.9% (p < 0.001) for men and 5.4% (p = 0.007) and 11.2% (p < 0.001) for women, for pre-exam and survey, respectively. Residual analyses showed that significant bias results when a regression model derived from one mode of self-report is used to correct BMI values estimated from the alternative mode.ConclusionsBoth modes significantly underestimated obesity prevalence. Underestimation of actual BMI is greater for survey than pre-exam self-report for both genders, indicating that equations adjusting for self-report bias must be matched to the self-report mode.

Objective vs self‐report assessment of height, weight and body mass index: Relationships with adiposity, aerobic fitness and physical activity

“…Findings of subsequent research have supported the aforementioned tendencies and indicate that they are global issues, with studies outside of the United States reporting similar issues . Furthermore, more recent evidence indicates that inaccuracies vary between genders, age groups and countries . In concurrence, evidence also suggests that, while overestimation of height is stable over time, the underestimation of weight appears to be increasing, particularly among heavier individuals …”

“…Perhaps the most obvious is that individuals may consciously under‐ or over‐report height or weight based on social desirability, while some may be oblivious to their height or weight. Other factors that may influence accuracy include assessment methods (ie, face to face, via the phone or via electronic or paper survey), anticipation of response verification, the measurement system (imperial vs metric) and whether or not variables are assessed to the nearest whole number. With respect to imperial vs metric, measuring height to the nearest centimetre rather than inch would be expected to be more accurate due to the larger‐scale range, whereas pounds would be expected to be more accurate than kilograms.…”

Prevalence of Smoking and Obesity Among U.S. Cancer Survivors: Estimates From the National Health Interview Survey, 2008–2012

“…The findings relied on self-reported data, which might not accurately capture cancer prevalence and is likely to underestimate BMI (Klein, Lee, Moss, Trentham-Dietz, & Klein, 2010; Scribani et al, 2014). Data on BMI status over treatment time was not available, and, therefore, it was not possible to examine how treatment might have affected BMI.…”

Prediction of Body Mass Index Using Concurrently Self-Reported or Previously Measured Height and Weight

“…If investigators collect self-reported height and weight from participants separately from other study variables it could also impact accuracy [23]. Finally, bias would likely have been different if self-reported weight and height had been collected in telephone interviews [10] or mailed survey [24] rather than in-person interviews.…”