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Modelling individual vulnerability to sexually transmitted infections to optimise intervention strategies: analysis of surveillance data from Kalamazoo County, Michigan, USA
  1. Claudio Owusu1,
  2. Kathleen M Baker2,3,
  3. Rajib Paul4,
  4. Amy B Curtis5
  1. 1 Department of Geography and Earth Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, USA
  2. 2 Department of Geography and Health Data Research, Western Michigan University, Kalamazoo, Michigan, USA
  3. 3 Health Data Research, Analysis and Mapping (HDReAM) Center, Western Michigan University, Kalamazoo, Michigan, USA
  4. 4 Department of Public Health Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, USA
  5. 5 Department of Interdisciplinary Health Sciences, Western Michigan University, Kalamazoo, Michigan, USA
  1. Correspondence to Dr Kathleen M Baker, Department of Geography and Health Data Research, Analysis and Mapping (HDReAM) Center, Western Michigan University, Kalamazoo, MI 49008, USA; kathleen.baker{at}


Objective We modelled individual vulnerability to STI using personal history of infection and neighbourhood characteristics.

Methods Retrospective chlamydia and gonorrhoea data of reported confirmed cases from Kalamazoo County, Michigan for 2012 through 2014 were analysed. Unique IDs were generated from the surveillance data in collaboration with local health officials to track the individual STI histories. We then examine the concept that individuals with similar STI histories form a ‘peer’ group. These peer group include: (1) individuals with a single chlamydia; (2) individuals with single gonorrhoea; (3) individuals with repeated cases of one type of STI and (4) individuals that were diagnosed with both infections during the study period. Using Kernel density estimation, we generated densities for each peer group and assigned the intensity of the infection to the location of the individual. Finally, the individual vulnerability was characterised through ordinary least square regression (OLS) using demographics and socioeconomic variables.

Results In an OLS regression adjusted for frequency of infection, individual vulnerability to STI was only consistently significant for race and neighbourhood-level socioeconomic status (SES) in all the models under consideration. In addition, we identified six areas in three townships in Kalamazoo County that could be considered for unique interventions based on overlap patterns among peer groups.

Conclusions The results provide evidence that individual vulnerability to STI has some dependency on individual contextual (race) and exogenous factors at the neighbourhood level such as SES, regardless of that individual’s personal history of infection. We suggest place-based intervention strategies be adopted for planning STI interventions instead of current universal screening of at-risk populations.

  • peer group
  • sexually transmitted diseases
  • retrospective studies
  • gonorrhea
  • chlamydia
  • demography

Statistics from


  • Handling editor Jane S Hocking

  • Contributors CO conceived the idea that there are different patterns of core groups of STI transmission and that a multifaceted approach may be needed to target interventions to reduce the burden of STI. KMB, CO and ABC contributed in conception and research design. CO contributed in geocoding all the cases using geographic information systems (GIS). CO and KMB contributed in visualising the data in GIS and developing the interventions priority map. RP, CO and KMB contributed in developing the statistical methods used in the data analysis. ABC provided the overall supervision and coordination for the research. CO and KMB wrote the first draft of the manuscript. All authors were involved in revising the manuscript critically in order to produce an important intellectual content and the final approved version.

  • Competing interests None declared.

  • Ethics approval Western Michigan University (WMU) Human Subjects Institutional Review Board (14-09-27).

  • Provenance and peer review Not commissioned; externally peer reviewed.

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