Validity of self-reported height and weight estimates in cognitively-intact and impaired elderly individuals.

OBJECTIVE

A high prevalence of undernutrition has been observed in the elderly, particularly in cognitively impaired or demented individuals. Self-reported height and weight were tested as simple and non-invasive methods to efficiently screen individuals at risk.

DESIGN

Cross-sectional study.

PARTICIPANTS

A subset of subjects (n=465) participating in the longitudinal follow-up phase of the Canadian Study of Health and Aging (CSHA) and comprising cognitively intact and impaired individuals as well as demented subjects.

MEASUREMENTS

Self-reported values of height and weight were compared to direct standard measurements using Pearson's correlation coefficients and linear regressions by cognitive status. Estimation bias was determined using paired Student t-tests. Sensitivity and specificity of body mass index (BMI) derived from self-reported data were calculated.

RESULTS

Self-reported and measured weights were highly correlated (r>.90) in all three categories of cognitive status. A tendency to underestimate their weight was observed in overweight women. Correlations of recalled to measured height were excellent in normal (r=.91) and good in cognitively impaired (r=.86) and demented (r=.85) subjects. A systematic overestimation of recalled height was observed, particularly among individuals of short stature. Self-reported BMI showed excellent sensitivity (>93%) in detecting underweight individuals in all three categories.

CONCLUSION

Self-reported height and weight data can be obtained in normal and cognitively-impaired elderly persons as well as in mild or moderate cases of dementia and can be used as a valid tool to screen for risk of undernutrition.