How valid are self-reported height and weight? A comparison between CATI self-report and clinic measurements using a large cohort study.
OBJECTIVE
To examine the relationship between self-reported and clinical measurements for height and weight in adults aged 18 years and over and to determine the bias associated with using household telephone surveys.


METHODS
A representative population sample of adults aged 18 years and over living in the north-west region of Adelaide (n = 1,537) were recruited to the biomedical cohort study in 2002/03. A computer-assisted telephone interviewing (CATI) system was used to collect self-reported height and weight. Clinical measures were obtained when the cohort study participants attended a clinic for biomedical tests.


RESULTS
Adults over-estimated their height (by 1.4 cm) and under-estimated their weight (by 1.7 kg). Using the self-report figures the prevalence of overweight/ obese was 56.0% but this prevalence estimate increased to 65.3% when clinical measurements were used. The discrepancy in self-reported height and weight is partly explained by 1) a rounding effect (rounding height and weight to the nearest 0 or 5) and 2) older persons (65+ years) considerably over-estimating their height.


CONCLUSIONS
Self-report is important in monitoring overweight and obesity; however, it must be recognised that prevalence estimates obtained are likely to understate the problem.


CONCLUSIONS
The public health focus on obesity is warranted, but self-report estimates, commonly used to highlight the obesity epidemic, are likely to be underestimations. Self-report would be a more reliable measure if people did not round their measurements and if older persons more accurately knew their height.
Taylor
Anne W
AW
Population Research and Outcome Studies, Department of Health, South Australia. anne.taylor@health.sa.gov.au
Dal Grande
Eleonora
E
Gill
Tiffany K
TK
Chittleborough
Catherine R
CR
Wilson
David H
DH
Adams
Robert J
RJ
Grant
Janet F
JF
Phillips
Patrick
P
Appleton
Sarah
S
Ruffin
Richard E
RE
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000886:Anthropometry / Q000295:instrumentation / Q000379:methods*; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D015331:Cohort Studies; D005260:Female; D019538:Health Care Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000175:diagnosis; D015203:Reproducibility of Results; D012648:Self Care / Q000295:instrumentation / Q000379:methods*; D012680:Sensitivity and Specificity; D012737:Sex Factors; D012959:Socioeconomic Factors