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Eileen Crimmins, Will Dow, Heather McCreath, and Teresa Seeman

Validation of Blood Pressure, Lipid Profiles and C-Reactive Protein Protocols for Population Survey. Eileen Crimmins, Will Dow, Heather McCreath, and Teresa Seeman. Background. Extensive literature on lab or clinic based collection of biomarkers

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Eileen Crimmins, Will Dow, Heather McCreath, and Teresa Seeman

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  1. Validation of Blood Pressure, Lipid Profiles and C-Reactive Protein Protocols for Population Survey Eileen Crimmins, Will Dow, Heather McCreath, and Teresa Seeman

  2. Background • Extensive literature on lab or clinic based collection of biomarkers • Epi studies have established detailed procedure manuals • Can these protocols be moved out of the lab/clinic? • What factors need to be considered?

  3. General Requirements for Biomarker Protocols • Carefully calibrated and maintained equipment • Specific processing and storage parameters • Trained technicians • Safety response protocols

  4. Candidate Protocols • Blood pressure / heart rate • Blood assays: lipids, metabolic and inflammatory markers, genetic analyses • Salivary assays: inflammatory markers, genetic analyses • Urinary assays: inflammatory markers • Pulmonary function

  5. Standard BP Protocol • Established by JNC VII • Trained & certified technicians (8+ hours) • Rest for 5 minutes in quiet room • Selection of appropriate cuff based on arm circumference • 3 readings by mercury sphyg, separated by 1 minute

  6. Previous BP Comparability Results • Compared w/ automatic devices • MESA: r > 0.80, underestimation that varied by group • CARDIA: high correlation, overestimation • Also done in HRS and NSAP MESA: Ni et al, Am J Hyp, 2006; CARDIA: internal communication

  7. Standard Lipid Protocol • Certified phlebotomist (intensive training) • Fasting 9+ hours • Separate serum within 8 hrs • Assay immediately or refrigerate/freeze

  8. Previous Lipid Comparability Results • Intra-class correlations > 0.85 for Cholestech • Framingham RS misclassification: 5% • May under-estimate high levels of TC and LDL-C • Small samples, relatively healthy Parikh, Am J Hlth Prom, 2009; Shephard, Clin Lab, 2007; Dale, Ann Pharmacother, 2008; Panz, Cardiovas J S Afr 2005

  9. Are Clinic Protocols Usable by Demographers? • Significant investment in technician training • Quick access to specialized equipment • Requires advance notice to participants (fasting)

  10. Pilot Study Design • Compare mercury sphyg and Omron automatic machine • Compare venipuncture and Cholestech blood spot analyzer for cholesterol and CRP • Working on adding Cardiocheck • Conduct in “ideal” conditions for clinical protocol

  11. Participants • 120, stratified by: • Age: 45-64, 65-74, 75-85 • Gender • Disease: Hypertensive vs Normal • 10 per cell • Recruit in multi-ethnic community

  12. Procedural Considerations: BP • BP always before blood collection • Randomize 1st BP device • Variety of cuff sizes if possible • Available for some sphyg, not Omron

  13. Procedural Considerations: Blood • Non-fasting • Blood spots analyzed immediately • Cholestech requirements: • Daily calibration (most cost-effective if multiple participants can be seen) • Cartridges require refrigeration

  14. Analysis Approach • Correlation between methods • Difference scores (t-tests) “Field” – “Gold Standard” • Bland-Altman plots • Assignment of disease status (Kappa)

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