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Measurement error inherent in diet and physical activity assessment tools hinders research to assess the associations between diet, physical activity, and health outcomes. Given the high penetrance of internet and mobile devices in the population and the availability of motion-sensing devices for monitoring physical activity, web-enabled instruments that can be accessed remotely and repeatedly administered are increasingly a practical and economical approach for measuring diet and physical activity exposures in health studies.

To understand the measurement error properties of both new and conventional diet and physical activity assessment tools, the Interactive Diet and Activity Tracking in AARP (IDATA) was conducted. The purpose of the IDATA study was to evaluate and compare the measurement error structure of diet and physical activity assessment tools against reference biomarkers.

IDATA Study participants were recruited from a list of AARP members aged 50-74 years residing in and around Pittsburgh, Pennsylvania. Eligible and consented participants visited the study center three times and also completed assigned activities at home over a 12-month period.

The following diagram illustrates how the cohort was defined starting with all of the participants recruited.

This diagram shows how the 4967 IDATA participants recruited were gradually narrowed down into the 1082 participants that are part of the CDAS population.

  • Step 1: Exactly 4967 patients were recruited.
    • Of these, 1452 patients were never screened by phone. Reasons include:
      • Refused screening (n=186)
      • Excluded due to meeting quota (n=1259)
      • Study closeout (n=7)
  • Step 2: Exactly 3515 patients were screened by phone.
    • Of these, 1448 patients were screened ineligible by phone. Reasons include:
      • Health-related, study-related, and diet-related (n=38)
      • Health-related and study-related (n=88)
      • Health-related and diet-related (n=116)
      • Study-related and diet-related (n=49)
      • Health-related (n=551)
      • Study-related (n=183)
      • Diet-related (n=406)
      • Unspecified (n=17)
  • Step 3: Exactly 2067 patients were screened eligible by phone.
    • Of these, 904 never went to clinic. Reasons include:
      • Declined clinic visit (n=595)
      • Excluded due to meeting quota (n=92)
      • Too much time commitment (n=93)
      • Travelling issues (n=11)
      • Loss of interest (n=37)
      • Worried about health effects (n=9)
      • Unspecified (n=67)
  • Step 4: Exactly 1163 patients were screened at clinic.
    • Of these, 30 were screened ineligible at clinic. Reasons include:
      • Health-related and study-related (n=1)
      • Health-related (n=25)
      • Study-related (n=1)
      • Diet-related (n=3)
  • Step 5: Exactly 1133 patients were screened eligible at clinic.
    • Of these, 3 were missing consent.
  • Step 6: Exactly 1130 patients consented.
    • Of these, 20 had no data.
  • Step 7: Exactly 1110 patients were in cohort.
    • Of these, 28 had no specimen consent.
  • Step 8: The 1082 remaining patients became the CDAS population.


Participants were assigned to Groups 1, 2, 3, or 4 and followed a specified 12-month assessment protocol. Groups 1 and 3 followed the same assessment schedule whereby reference biomarkers were collected during the first month of assessment. Groups 2 and 4 followed an alternative assessment schedule whereby reference biomarkers were collected during the sixth month of assessment. A subsample of participants (designated by S below; n= 66) were recruited to provide repeated measures of reference biomarkers.

Months for Groups 1 & 3
M0 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11
Clinic VisitXXX
Physical Activity
ACTIGRAPHXX
ACTIVPALXX
ACT24XXXXXX
Fitness TestX
PAQ-CHAMPSXX
PAQ-AARPXX
PAQ-BRFSSXX
PAQ-HarvardX
PAQ-StanfordXX
HRMX
Dietary
ASA24XXXXXX
DHQ-IIXX
Daily Food ListXX
4-Day Food RecordXX
Biomarkers
DLWXS
UrineXX
SalivaXX
Status
AnthropometryXXX

S = subsample only



Months for Groups 2 & 4
M0 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11
Clinic VisitXXX
Physical Activity
ACTIGRAPHXX
ACTIVPALXX
ACT24XXXXXX
Fitness TestX
PAQ-CHAMPSXX
PAQ-AARPXX
PAQ-BRFSSXX
PAQ-HarvardX
PAQ-StanfordXX
HRMX
Dietary
ASA24XXXXXX
DHQ-IIXX
Daily Food ListXX
4-Day Food RecordXX
Biomarkers
DLWXS
UrineXX
SalivaXX
Status
AnthropometryXXX

S = subsample only