Validity of diabetes self-reports in the Women's Health Initiative: comparison with medication inventories and fasting glucose measurements.
OBJECTIVE
Although diabetes is conveniently assessed by self-report, few validation studies have been performed. Therefore, we studied whether self-report of prevalent and incident diabetes in Women's Health Initiative (WHI) participants was concordant with other diagnostic evidence of diabetes.


METHODS
A total of 161 808 postmenopausal women aged 50-79 were enrolled at 40 clinical centers in the U.S. in 1993-1998 and followed prospectively. At baseline, prevalent medication treated diabetes was defined as a self-report of physician diagnosis and treatment with insulin or oral antidiabetic drugs. During followup, incident treated diabetes was defined as a self-report of a new physician diagnosis of diabetes treated with insulin or oral drugs. Diabetes self-reports were compared with medication inventories and fasting glucose levels at baseline and during follow-up.


RESULTS
At baseline, self-reported treated diabetes was concordant with the medication inventory in 79% of clinical trial, and 77% of observational study participants. Self-reported incident treated diabetes was concordant with the medication inventory in 78% between baseline and Year 1 in the clinical trials, in 62% between Year 1 and Year 3 in the clinical trials, and in 72% between baseline and Year 3 in the observational study. Over similar periods, 99.9% of those who did not report treated diabetes had no oral antidiabetic drugs or insulin in the medication inventory. At baseline, about 3% not reporting diabetes had fasting glucose >126 mg/dl, and 88% of these subjects subsequently reported treated diabetes during 6.9 years of follow-up.


CONCLUSIONS
Incident self-reported diabetes treated by lifestyle alone was not determined in WHI. Medication inventories may have been incomplete and fasting glucose may have been lowered by treatment; therefore, concordance with self-reported treatment or fasting glucose > or = 126 may have been underestimated.


CONCLUSIONS
In the WHI, self-reported prevalent and incident diabetes was consistent with medication inventories, and a high proportion of those with undiagnosed diabetes subsequently reported diabetes treatment. Self-reports of ;treated diabetes' are sufficiently accurate to allow use in epidemiologic studies.
HealthPartners Research Foundation, Minneapolis, MN 55440-1524, USA, KarenL.Margolis@HealthPartners.Com
Karen L
KL
Margolis
Lihong Qi
Robert
R
Brzyski
Denise E
DE
Bonds
Barbara V
BV
Howard
Sarah
S
Kempainen
Simin Liu
Jennifer G
JG
Robinson
Monika M
MM
Safford
Lesley T
LT
Tinker
Lawrence S
LS
Phillips
D000368:Aged; D001786:Blood Glucose / Q000032:analysis*; D016009:Chi-Square Distribution; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000453:epidemiology; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D015994:Incidence; D007328:Insulin / Q000627:therapeutic use; D008019:Life Style; D008875:Middle Aged; D017698:Postmenopause; D015995:Prevalence; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D012650:Self Disclosure; D014481:United States / Q000453:epidemiology; D016387:Women's Health
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin