diabetes incidence and long-term exposure to air pollution: a cohort study zorana jovanovic andersen...
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Diabetes incidence and long-term exposure to air pollution: a cohort study
Zorana Jovanovic Andersen 14.09.2011 ISEE
Diabetes Diabetes epidemic, cased in large part by
obesity epidemic and physical inactivity Metabolic disease, high blood sugar, type-2,
insulin resistance In USA
Background: Diabetes & Air Pollution Diabetes established modifier of a link between air
pollution and CVD (inflammation, endothelial dysfunction, prothrombotic changes, altered heart rate variability)
Biological mechanism prolonged exposure to air pollution involves inflammation in adipose tissue, increased blood glucose levels, insulin resistance, glucose intolerance in mice
Short-term exposure to elevated air pollution linked to increased risk of diabetes mortality and hospitalization
Aim of this study
We studied the association between traffic-related air pollution levels at the residence and the risk for diabetes in an elderly Danish cohort, and tested for an effect modification by lifestyle, education, and co-morbid conditions.
Methods - Cohort Danish Diet, Cancer and Health cohort 57 053 subjects, Copenhagen and Aarhus Interviewed in 1993-1997 (baseline) Age 50-65 years Linkage to Central Population Registry and Danish
Address Database - residential address history (1971) Linkage to Danish National Diabetes Register (1995)
for assessment of health outcome
Danish Diabetes Register The NDR was established by linking existing
nationwide administrative records in the Danish healthcare systemSource of Data Inclusion Criteria
National Patient Register (NPR)hospitals discharge diagnoses (1994)
hospital admission for diabetes: ICD10: DE10-14, DH36.0, DO24, or ICD8: 249, 250
National Health Insurance Registry (NHISR)with information of all services provided by general and specialist practitioners (1973)
1. chiropody for diabetic patients; 2. five blood glucose measurements within 1 year3. two blood glucose measurements per year for five consecutive years registered
Register of Medicinal Product Statistics (RMPS) containing all prescriptions dispensed at Danish pharmacies (1993)
second purchase of insulin or oral glucose-lowering drugs within 6 months
Danish Diabetes Register Results of blood glucose measurements are not
included 50-60% of the patients > 1 inclusion criterion Not possible to distinguish type 1 and type 2
diabetes Due to different dates of initiation of the underlying
registers and accumulation of prevalent cases, only incidence values after 1 January 1995 were found to be reliable
Incidence of diabetes was defined as the earliest record in the diabetes register occurring after 1 January 1995, between baseline (1993-1997)
and 27 June 2006.
Methods – Air Pollution Exposure AirGIS dispersion model, sum of:
1) regional background, 2) urban background, & 3) street level contribution
Input for AirGIS model Street/building geometry Street network and traffic data Meteorology
Road centre line
Address point
Building
Road centre line
Address point
Building
GIS Maps building height, street width, open sector
Traffic counts, emission factors, density, speed, types, variation patterns over time
Methods – Air Pollution Exposure
AirGIS Model output: Annual mean NO2 /NOx
concentrations at individual address
NOX (Class)
680000 690000 700000 710000 720000 730000
6140000
6150000
6160000
6170000
6180000
6190000
6200000
6210000
6220000
1 2 3 4 5 6 7 8 9 10
a)
Lille Valby
wind
Leeward Windward
Recirculated pollution
Direct emission
Background pollution
Flow and dispersion inside a street canyon
Methods – Statistical Model
Cox proportional hazards model, left truncation at age at baseline, and right censoring at age at hospital admission for ACS, death, emigration, or 27 June 2006
NO2 /NOx ,time-dependent variables, the estimates per IQR
Confounders: smoking (status, intensity, duration, ETS), occupational exposures, BMI, educational level, fruit consumption
Effect modification: interaction term, Wald-test Spline (rcs) in R, for dose-repsonse curve
Results5705
35181
8
4040
2877
Exclusions:- 571 cancer before baseline- 962 missing address or geocode - 1 341 missing address - 1 147 self-reported diabetes at baseline- 173 diabetes record in the NDR before
baseline- 6 with diabetes between baseline and
01.01.1995- 1 035 missing covariates 7.8% diabetes originally included in NDR
Incidence rate: 8 per1 000 person-years
5.5% diabetes ‘strict definition’Incidence rate: 5.7 per 1 000 person-years
”Confirmed Diabetes”
Original Cohort
Final Study Population
”All Diabetes”
Exclusion of 1163 included solely due to blood glucose measurements
Results: Main Analysis
Model WITHOUT waist-to-hip ratio: 1.05 (1.02-1.10)
Model WITHOUT BMI and waist-to-hip ratio: 1.08 (1.04-1.12)
Results: dose-response
NO2 (µg/m3)
log
Re
lativ
e H
aza
rd
10 20 30 40 50 60
-0.2
0.0
0.2
0.4
0.6
0.8