Research for the Improvement in Measurement Methods and the Effect of Sodium Intake on Cardiovascular Health
Condition: Sodium Intake; General Population
Study type: Observational

Summary: 
      Epidemiological, clinical and animal-experimental evidence shows a direct relationship
      between dietary sodium intake, blood pressure and cardiovascular event. Diverse questionnaire
      and 24 hour urinary sodium measurement are used to estimate sodium intake. Complete
      reflection of eating and cooking habits to the dietary survey method is difficult.
      Furthermore, the differences of database between countries make it difficult to compare the
      amount of sodium intake between countries. It is also difficult to consider individual
      variation of cooking and eating habits. Due to limitations of dietary survey method, WHO
      recommended 24 hour urinary sodium measurement to estimated sodium intake in the population
      survey, and many countries are adopting. However, in Korea National Health and Nutrition
      Examination Survey, only dietary survey method has been used.

      The present survey study was designed 1) to test the feasibility of 24 hour urinary sodium
      measurement for the estimation of sodium intake (including percentage of complete 24 hour
      urine sample collection) in the population based study; 2) to establish feasible method of 24
      hour urinary sodium measurement; 3) to compare 24 hour urinary sodium measurement to the
      dietary survey method; and 4) to estimate the sodium intake by 24 hour urinary sodium
      measurement in Goyang city general population (aged 20-70 years).
    

Detailed description: 
      Measurements: should be performed for 2 days

        1. 24 hour urine Na, K and Creatinine, 24 hour urine amount

             1. Calculation of urine completeness index : Creatinine/(21 x Bwt)

             2. Definition of incomplete urine collection: complete index less than 0.7 and loss of
                urine more than one time or 100 mL

        2. 24 hour ambulatory blood pressure

             1. mobile-O-graph (IEM GmbH)

             2. measurement interval: 30 minutes

        3. Measurement of peripheral blood pressure : microlife WatchBP office

             1. Sitting position

             2. After 5 minutes resting

             3. Peripheral systolic BP (pSBP), Peripheral diastolic BP (pDBP),

        4. Central aortic blood pressure

             1. SphygmoCor (AtCor Medical, Australia)

             2. Central systolic blood pressure

        5. Pulse wave velocity

             1. VP2000 (Colin, Japan)

             2. pulse wave velocity (PWV): carotid-femoral Pulse Wave Velocity, heart-femoral Pulse
                Wave Velocity and brachial-ankle Pulse Wave Velocity

             3. distance measured by tape: distance from suprasternal notch to carotid artery,
                distance from suprasternal notch to femoral artery

             4. Silent environment

        6. Electrocardiography

        7. Blood chemistry and complete blood count

             1. Measure at the morning of first day after overnight fasting

             2. complete blood count, blood urea nitrogen/Creatinine, Fasting blood glucose, Total
                cholesterol, triglyceride, HDL cholesterol

      Measurement protocol

        1. 1st day

             1. Visit hospital before 9:00 AM after overnight fasting

             2. Sampling of venous blood

             3. start 24 hour urine collection from 9:00 AM (with education for complete
                collection)

             4. start 24 hour ambulatory blood pressure monitoring, in parallel with 24 hour urine
                collection

        2. 2nd day

             1. Measure central aortic blood pressure

             2. Measure Pulse Wave Velocity

             3. Electrocardiography
    

Observational model: Ecologic or Community
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        1. Representative population of Goyang city who were randomly selected by digit dialing
             (RDD) method

          2. Volunteers who are reside in Goyang city
      
Keywords: sodium; blood pressure; pulse wave velocity; random digit dialling