Over the last century, American childhood deaths associated with accidental poisoning had been significantly reduced. Recent reports, however, indicate that not only are pediatric drug exposures on the rise, but the associated clinical outcomes are worsening in severity. These medication exposures ultimately result in increased healthcare utilization. ^1–5 Poisoning is one of the top reasons for Emergency Department (ED) visits in the 1 to 5 year age group in the United States(US).⁶ Due to their exploratory nature, children in this age group are particularly vulnerable to unintentional self-exposures.^7,8 New prevention strategies are required to reduce drug exposures and to decrease the associated healthcare burden.^9,10 Identification of medication poisoning locations and understanding the communities at risk for injury is essential to revising prevention strategies. Geographic information systems (GIS) is a computerized platform designed to collect, manage, and analyze spatial and non-spatial data. ¹¹.Public health campaigns have utilized GIS and spatial scan statistics to assess regional variation in substance abuse prevalence, alcohol related injury, as well as to plan and assess the impact of preventive interventions in childhood lead poisoning. ^12–14

A critical gap exists in the literature regarding geographic trends and population characteristics of unintentional, drug exposures in children. In this study, we use poison center data, United States (US) Census information and spatial statistics to assess regional patterns of drug exposure in children < 5 years. The purpose of this study was to assess regional pharmaceutical poisoning rates, identify locations and populations at risk for injury, and determine geographic variations in the poisoning injury resulting in health services utilization. We hypothesized that drug exposures exist in clusters and are not randomly distributed over space. We performed a spatial analysis on all calls to the poison center regarding pediatric drug exposure and on the subset of calls that resulted in referrals for medical evaluation. We then compared population characteristics of ZIP codes with and without cluster patterns.

From January 1st, 2006 to December 31st, 2010, there were 94,081 unique records involving children < 5 years reported to the Pittsburgh Poison Center from a non-healthcare facility (Figure 1). There were 390 calls from outside the service area; 99 calls were located in 20 ZIP codes where no children < 5 years were reported by 2010 US Census. The final sample included 26,685 exposures with 877 drug exposures resulting in HCF referral (Table 1). The study area included 280,855 children < 5 years across 873 ZIP Codes. A scanning window set at 50% identified a large primary cluster occupying a large portion of southwest Pennsylvania. By restricting the window size to 5%, smaller clusters were identified with minimum risk of missing significant regional-level clusters. We identified 22 exposure clusters and 5 referral cluster (Figure 2). The primary cluster from each of these samples was identified in distinctly different geographic regions; the primary exposure cluster was located in Warren, PA (RR=1.7), while the primary HCF referral cluster was identified in Erie, PA (RR=37.5). While 9.5% of the 324 ZIP codes in the exposure cluster were also identified in a referral cluster (n = 31), 65% of 89 ZIP codes in referral clusters were not initially identified in the exposure clusters, demonstrating minimally overlapping geographic pattern (n =58).

ZIP codes within exposure clusters were urban and more densely populated compared to ZIP codes not in an exposure cluster (Table 2). These ZIP codes were also statistically different in terms of median household size, educational attainment, and women head of household; the results from the regression analysis are depicted in Table 3.

We hypothesized pediatric drug exposures exist in clusters and are not randomly distributed across western Pennsylvania. Our principal findings demonstrate pediatric drug exposures do, in fact, exist in distinct geographic patterns. Moreover, ZIP codes in referral clusters were geographically distinct from the exposure clusters and were characterized as largely rural, impoverished, and with high unemployment and school dropout rates.

These results have significant implications as they provide a starting point for further investigation into the relationship between location and the social environment of children with unintentional drug poisoning. While previous studies have applied spatial analysis to understand patterns in adult prescription drug use, we found a dearth of studies using spatial techniques to investigate geographic patterns of medication poisoning in children.^17–20 Moreover, there is a critical gap in our understanding of the socioeconomic context of American childhood poisoning.^21–24 This investigation’s demographic characterization offers some first insights to the socio-economic context of American childhood poisoning. The regression model indicates population density had a moderate effect on a ZIP code falling within an exposure cluster while education status appears to have a small effect. These findings are consistent with previous studies identifying population density as a positive predictor of poison center utilization, while less educated populations are associated with a decrease in poison center utilization. Poison center utilization is influenced by poison center awarenesss.³⁰ In more densely populated and more educated communities, knowledge of poison center service may proliferate more easily, resulting in the increase of a population’s awareness of poison center services. This may translate into more calls regarding drug exposures.

International literature has investigated the relationship of socioeconomic disparity and childhood poisoning.^25,26 In the United Kingdom, children from lower socioeconomic status were at greater risk of death associated with poisoning when compared to children from more affluent status. Lower socioeconomic status may be a surrogate marker of suboptimal child supervision which might result in neglect and increased child injury.^27–29 Our findings suggest a similar relationship may exist in impoverished, rural American communities with high unemployment and school dropout rates.

This study offers a novel strategy in closing this gap in the poison prevention literature. Understanding where clusters exist at a local level offers target areas for revised prevention strategies. For example, within these high risk areas, poison injury resources may be dispensed at the point-of-sale of prescription medications. Professional associations might create promotional campaigns to educate pharmacists in directing customers to keep medications in original child-resistant containers; pediatricians can be prompted to discuss poison prevention tactics with families of young children living in identified cluster areas. Neighborhood and community social networks in high risk areas can be encouraged to organize “Take Back Medications” campaigns to safely and properly dispose of prescription medications. Drug exposure and drug poisoning cluster identification can also be useful to health departments by providing a means to measure the impact and performance of any poison intervention programs.

An important concept to consider is that the data sampled are from phone calls placed to the poison center; these calls may not necessarily reflect true exposure incidence, but rather a population’s utilization of poison center services. Decreased poison center utilization has been associated with increased healthcare utilization. Moreover, poison center underutilization in rural areas is believed to be associated with increased hospitalization.^31,32 Our findings support a similar pattern; if exposure clusters serve as a proxy for poison center utilization, then there exists a distinct pattern of referral clusters in rural communities, outside of these areas of high poison center use. Poison Center specialists do not consider proximity to a health care facility in the decision to refer a child for a medical evaluation. Specialists gather information based on pre-determined criteria and refer when clinical concern is high. In order to gain insight on this geographic disparity, future research will investigate potential differences in the type of medications that urban and rural children are exposed to.

While identifying locations of high rates for exposure allows important characterization of population attributes associated with increased poison center awareness, the locations with low rates are also of interest. Studies have indicated increased poison center utilization is associated with reductions in ED visits and hospital admissions as poison center specialists may facilitate safe medical management of low-risk poison exposures at home.^32,33 Therefore, raising poison center awareness in the ZIP codes in low rate cluster locations may lead to reductions in healthcare costs associated with unnecessary medical evaluations. Past efforts to raise poison center awareness such as mass media mailings, however, have been challenging and expensive.^34–36 A cost-effective strategy may be to use spatial analysis to perform a community-based assessment to identify communities within low utilization clusters.

We conclude that drug exposure and drug exposure with HCF referral exist in distinct geographical clusters. ZIP codes identified within these clusters have specific population characteristics. This study offers a starting point for subsequent investigations into the geographical and social patterns of pediatric drug exposures and associated healthcare utilization.