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Spatial Clustering of Scleroderma in Three Michigan Counties

This study explores the spatial clustering of scleroderma, a chronic connective tissue disease, in three Michigan counties. The prevalence, incidence, and distribution of cases are analyzed using statistical methods. The study aims to identify potential environmental associations and understand the disease process.

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Spatial Clustering of Scleroderma in Three Michigan Counties

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  1.       Spatial Clustering of Scleroderma in Three Michigan Counties “The Toledo Twins” Sharon HensleyAlford Sarah Ann Cleveland      

  2. Background The disease that “turns people to stone” • Chronic, connective tissue disease • Unknown cause • Collagen accumulation in some organs Classifications • Localized • Systemic

  3. Who has scleroderma • Approximately 150,000 people in the United States • 4 times more women than men

  4. 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

  5. Diagnosis • Difficult • Involvement of several specialists • May take months to years

  6. 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.

  7. Age Distribution of Cases

  8. Sex Distribution • 134 Females • 37 Males • 3.62 times more females than males

  9. Etiologies • UNKNOWN • Possibilities include: • silica dust • vinyl chloride monomer • pet ownership • some solvents • appetite suppressants

  10. Significance To Explore... • Environmental associations • Spatial pattern  Disease process

  11. Disease Data Incidence data for 1989-1991 (N=171) Three counties: Macomb Oakland Wayne Population Data 1990 Census data Block and Tract divisions Materials

  12. Methods • Gathering population data • Finding census data • Extract pertinent information • Geocoding cases • ArcView Batch Match • Digitizing unmatched cases

  13.  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

  14. Batch-Matched Addresses n=148 Digitized n=13 Non-matched n=18 Unable to Digitize n=5 Matching Rate 171 Original 5 Unmatchable Addresses n=166 161 Matched/166 Total 96% Matching Rate

  15. Statistical Analysis Null Hypothesis: No spatial clustering Alter. Hypothesis: Spatial clustering Test statistic: Ipop, Moran’s I Statistical Program: STAT!

  16. 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/Tracts

  17. STAT 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) Macomb/Block

  18. STAT 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/Tracts

  19. Oakland/Blocks

  20. STAT 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/Tracts

  21. Wayne/Blocks

  22. 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

  23. Thank You First Honors: Andy Long Mark Wilson Dr. Mayes Geoff Jacquez

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