Spatial Clustering of Scleroderma in Three Michigan Counties
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Transcript of Spatial Clustering of Scleroderma in Three Michigan Counties
Spatial Clustering of Scleroderma in Three Michigan
Counties“The Toledo Twins”
Sharon HensleyAlford
Sarah Ann Cleveland
Background
The disease that “turns people to stone”– Chronic, connective tissue disease– Unknown cause– Collagen accumulation in some organs
Classifications– Localized– Systemic
Who has scleroderma
• Approximately 150,000 people in the United States
• 4 times more women than men
Symptoms May Include
• Raynaud’s Phenomenon
• Swelling of hands and feet
• Pain and stiffness of joints
• Thickening of the skin
• Kidney, heart, and lung involvement
• Oral, facial, and dental problems
Diagnosis
• Difficult
• Involvement of several specialists
• May take months to years
Rates in Study Area
Prevalence
• 242 cases per 1million adults
Incidence
• 19 new cases per 1 million adults per year
Reference: Prevalence, incidence and survival rates of systemic sclerosis in the Detroit metropolitan area. Mayes et al.
Age Distribution of Cases
Age Distribution of Scleroderma
0
2
4
6
8
10
1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86
Age
Num
ber
of C
ases
Sex Distribution
• 134 Females• 37 Males
• 3.62 times more females than males
78%
22%
020406080100120140160
Males Females
Num
ber o
f Cas
es
Etiologies
• UNKNOWN
• Possibilities include:– silica dust– vinyl chloride monomer– pet ownership– some solvents– appetite suppressants
Significance
To Explore...
• Environmental associations
• Spatial pattern Disease process
Materials
Disease Data– Incidence data for
1989-1991 (N=171)
– Three counties:• Macomb
• Oakland
• Wayne
Population Data– 1990 Census data
– Block and Tract divisions
Methods
• Gathering population data– Finding census data– Extract pertinent information
• Geocoding cases– ArcView Batch Match– Digitizing unmatched cases
Working with Unmatched Cases
• Verifying address: US Post: www.usps.gov
• Using web map programs– Mapquest: www.mapquest.com
• gives county lines
– Vicinity: www.mablast.com
• Digitizing
Matching Rate
171 Original
5 Unmatchable Addresses
n=166
Batch-Matched Addresses
n=148
Non-matched
n=18
Digitized
n=13
Unable to Digitize
n=5161 Matched/166 Total
96% Matching Rate
Statistical Analysis
Null Hypothesis: No spatial clustering
Alter. Hypothesis: Spatial clustering
Test statistic: Ipop, Moran’s I
Statistical Program: STAT!
Macomb/Tracts
Assumption R
Variance : 0.0000000
z-score : -0.3175953
Significance : 0.7507920 (2-tailed)
Approximation
Variance : 0.0000000
z-score : -0.3121641
Significance : 0.7549158 (2-tailed)
Simulation
Significance : 0.8800000 (2-tailed)
STAT Output 4/13/1999
Results from Ipop test
Number of runs : 99
Ipop calculations
Areas (m) : 194
cases (n) : 30
Population (x) : 724110
Ipop : -0.0000099
Ipop' : -0.2377846
E[I] : -0.0000014
% within : 99.9752702
% among : 0.0247298
Macomb/BlockSTAT Output 4/14/1999
Results from Ipop test
Number of runs : 99
Ipop calculations
Areas (m) : 661
cases (n) : 30
Population (x) : 724112
Ipop : -0.0000208
Ipop' : -0.5008514
E[I] : -0.0000014
% within : 99.9957345
% among : 0.0042655
Assumption R
Variance : 0.0000000
z-score : -0.3930764
Significance : 0.6942630 (2-tailed)
Approximation
Variance : 0.0000000
z-score : -0.3855452
Significance : 0.6998335 (2-tailed)
Simulation
Significance : 0.6400000 (2-tailed)
Oakland/TractsSTAT Output 4/13/1999
Results from Ipop test
Number of runs : 99
Ipop calculations
Population (x) : 1101540
Ipop : 0.0000033
Ipop' : 0.0817093
E[I] : -0.0000009
% within : 99.8772695
% among : 0.1227305
Assumption R
Variance : 0.0000000
z-score : 0.2045747
Significance : 0.8379044 (2-tailed)
Approximation
Variance : 0.0000000
z-score : 0.2022084
Significance : 0.8397538 (2-tailed)
Simulation
Significance : 0.5600000 (2-tailed)
Oakland/Blocks
Wayne/TractsSTAT Output 4/13/1999
Results from Ipop test
Number of runs : 99
Ipop calculations
Areas (m) : 632
cases (n) : 86
Population (x) : 2159815
Ipop : -0.0000062
Ipop' : -0.1565116
E[I] : -0.0000005
% within : 100.4700628
% among : -0.4700628
Assumption R
Variance : 0.0000000
z-score : -0.3578355
Significance : 0.7204664 (2-tailed)
Approximation
Variance : 0.0000000
z-score : -0.3542334
Significance : 0.7231640 (2-tailed)
Simulation
Significance : 0.9200000 (2-tailed)
Wayne/Blocks
Discussion
Limitations of Analysis– Position uncertainty– Residential history– Reliability of census data
Future Analysis– Stratification by age, sex, race– 3 county combination analysis– Space/Time Analysis
Thank You
First Honors: Andy Long
Mark Wilson
Dr. Mayes
Geoff Jacquez