Andrew M. Jones 583health limitations; these include lung function tests, such as forced expiratory vol-
ume (FEV) and forced vital capacity (FVC), as measured by a spirometer, and grip
strength, measured by a gripometer.
Datasets which contain biomarkers and that have been used in economic
research include ELSA, the UK Health and Lifestyle Survey (HALS), the US Health
and Retirement Survey (HRS), the Health Survey of England (HSE), the UK National
Child Development Study (NCDS) and the more recent cohort studies, the US
National Health and Nutrition Examination Surveys (NHANES), SHARE, and the
Whitehall Study of English civil servants. To take ELSA as an example: participants
in the study are visited by a registered nurse who takes measurements of blood
pressure; lung function; height, weight and the waist-to-hip ratio; grip strength,
as a measure of upper body strength; a measure of lower body strength, based on
standing up from a chair without using the arms; a saliva sample, that is used
to measure cortisol, which is a marker for stress; and a blood sample, which is
used to test total cholesterol, HDL cholesterol, fibrinogen, CRP, ferritin, glycated
haemoglobin and haemoglobin. The blood samples from ELSA and from wave 7 of
the NCDS will allow DNA to be extracted. DNA can also be collected using mouth
or cheek swabs (as in the US AddHealth Survey).
Bankset al. (2006) study the socioeconomic gradient in health in the UK
and the US and they compare both self-reported outcomes and objective out-
comes based on biomarkers. To do this they use the ELSA data for the UK and
the HRS and NHANES data for the US. The self-reported measures include the
general question on SAH as well as self-reported indicators of chronic condi-
tions, such as diabetes, hypertension and cancer. The biomarkers are glycosated
hemoglobin levels above 6.5%, as a marker for diabetes; systolic blood pressure
over 140 mm Hg, and diastolic blood pressure over 90 mm Hg, as a measure of
hypertension; CRP greater than 3 mg/L, as a marker of high risk of arteriosclero-
sis; fibrinogen over 400 mg/dl, as a marker for cardiovascular disease, and HDL
cholesterol over 40 mg/dl, as an indicator of reduced risk of coronary heart dis-
ease. Bankset al.(2006) find that, on average, respondents in the US reported
better SAH, but the opposite holds true for the biomarkers. Their results show a
strong socioeconomic gradient in self-assessed health, self-reported diseases and
in the biomarkers. The gradient appears strongest for the biomarkers. Comparing
the self-reported data with the biomarkers allows a measure of the socioeconomic
gradient in undiagnosed cases. A gradient is apparent for diabetes, but not for
hypertension.
A novel feature of Adda and Cornaglia (2006) is the use of biomarkers, in this
case cotinine, within an economic study of smoking. Cotinine is a metabolite
of nicotine and can be used as a biomarker for levels of tobacco consumption
that is not contaminated by problems of measurement error, such as recall bias
and deliberate deception, that may affect self-reported consumption. The study
shows that smokers engage in compensatory behavior, increasing their intensity
of smoking and offsetting the impact of tobacco tax increases. Data on cotinine
is collected from saliva samples as part of the repeated cross-section data in the
NHANES for 1999–2000. Evidence based on the biomarker is contrasted with