Spatial accessibility of primary care: concepts, methods and challenges

Primary care is recognized as the most important form of healthcare for maintaining population health because it is relatively inexpensive, can be more easily delivered than specialty and inpatient care, and if properly distributed it is most effective in preventing disease progression on a large scale. Recent advances in the field of health geography have greatly improved our understanding of the role played by geographic distribution of health services in population health maintenance. However, most of this knowledge has accrued for hospital and specialty services and services in rural areas. Much less is known about the effect of distance to and supply of primary care on primary care utilization, particularly in the U.S. For several reasons the shortage of information is particularly acute for urban areas, where the majority of people live. First, explicit definitions and conceptualizations of healthcare access have not been widely used to guide research. An additional barrier to progress has been an overwhelming concern about affordability of care, which has garnered the majority of attention and research resources. Also, the most popular measures of spatial accessibility to care – travel impedance to nearest provider and supply level within bordered areas – lose validity in congested urban areas. Better measures are needed. Fortunately, some advances are occurring on the methodological front. These can improve our knowledge of all types of healthcare geography in all settings, including primary care in urban areas. This paper explains basic concepts and measurements of access, provides some historical background, outlines the major questions concerning geographic accessibility of primary care, describes recent developments in GIS and spatial analysis, and presents examples of promising work

Fluctuating Dental Asymmetry and Stress at the Averbuch Site (40DV60), Nashville, Tennessee

There may exist bilateral asymmetry in tooth size in which neither side tends to be larger within a population. Such a bilaterally random distribution of asymmetry is called fluctuating dental asymmetry. One of its major causes is the exposure of individuals to stress during the time of tooth formation. Stressors known to increase fluctuating dental asymmetry are protein deficiency, heat, cold, and noise; there are probably many others as yet undiscovered. This study explores the patterns of fluctuating dental asymmetry at the Averbuch site, a Mississippian village and three cemeteries near Nashville, Tennessee. The effects of tooth size, dentition type, sex, and cemetery affiliation on dental asymmetry are examined. Regression analysis shows that there is a scaling effect of tooth size on asymmetry, necessitating that tooth size be corrected for before the other factors are examined. Analysis of correlation coefficients reveals that four pairs of deciduous teeth are significantly less symmetrical and two pairs are significantly more symmetrical than the permanent antimeres. Analysis of correlation coefficients and ANOVA reveal that females are somewhat more symmetrical than males, suggesting that they are developmentally more stable than males. Although it is difficult to interpret the meaning of the deciduous-permanent differences, both types of dentition show the same intercemetery patterns of dental asymmetry. Cemetery 2 (undatable) is the most asymmetrical, Cemetery 3 is the least asymmetrical, and Cemetery 1 is intermediate in its rank of asymmetry. Archeological evidence suggests that Cemetery 1 is younger than Cemetery 3. These findings support the hypothesis of increasing population pressure in the Nashville Basin at the time of the site\u27s occupation. However, the true temporal relationship of the cemeteries is not known for certain. Further statements await the analysis of archeological materials recovered from the site

Pediatric appendicitis rupture rate: a national indicator of disparities in healthcare access

BACKGROUND: The U.S. National Healthcare Disparities Report is a recent effort to measure and monitor racial and ethnic disparities in health and healthcare. The Report is a work in progress and includes few indicators specific to children. An indicator worthy of consideration is racial/ethnic differences in the rate of bad outcomes for pediatric acute appendicitis. Bad outcomes for this condition are indicative of poor access to healthcare, which is amenable to social and healthcare policy changes. METHODS: We analyzed the KID Inpatient Database, a nationally representative sample of pediatric hospitalization, to compare rates of appendicitis rupture between white, African American, Hispanic and Asian children. We ran weighted logistic regression models to obtain national estimates of relative odds of rupture rate for the four groups, adjusted for developmental, biological, socioeconomic, health services and hospital factors that might influence disease outcome. RESULTS: Rupture was a much more burdensome outcome than timely surgery and rupture avoidance. Rupture cases had 97% higher hospital charges and 175% longer hospital stays than non-rupture cases on average. These burdens disproportionately affected minority children, who had 24% – 38% higher odds of appendicitis rupture than white children, adjusting for age and gender. These differences were reduced, but remained significant after adjusting for other factors. CONCLUSION: The racial/ethnic disparities in pediatric appendicitis outcome are large and are preventable with timely diagnosis and surgery for all children. Furthermore, estimating this disparity using the KID survey is a relatively straightforward process. Therefore pediatric appendicitis rupture rate is a good candidate for inclusion in the National Healthcare Disparities Report. As with most other health and healthcare disparities, efforts to reduce disparities in income, wealth and access to care will most likely improve the odds of favorable outcome for this condition as well

Do pediatric hospitalizations have a unique geography?

BACKGROUND: In the U.S. small-area health services research studies are often based on the hospital service areas (HSAs) defined by the Dartmouth Atlas of Healthcare project. These areas are based on the geographic origins of Medicare Part A hospital patients, the great majority of whom are seniors. It is reasonable to question whether the geographic system so defined is appropriate for health services research for all ages, particularly for children, who have a very different system of healthcare financing and provision in the U.S. METHODS: This article assesses the need for a unique system of HSAs to support pediatric small-area analyses. It is a cross-sectional analysis of California hospital discharges for two age groups – non-newborns 0–17 years old, and seniors. The measure of interest was index of localization, which is the percentage of HSA residents hospitalized in their home HSA. Indices were computed separately for each age group, and index agreement was assessed for 219 of the state's HSAs. We examined the effect of local pediatric inpatient volume and pediatric inpatient resources on the divergence of the age group indices. We also created a new system of HSAs based solely on pediatric patient origins, and visually compared maps of the traditional and the new system. RESULTS: The mean localization index for pediatric discharges was 20 percentage points lower than for Medicare cases, indicating a poorer fit of the traditional geographic system for children. The volume of pediatric cases did not appear to be associated with the magnitude of index divergence between the two age groups. Pediatric medical and surgical case subgroups gave very similar results, and both groups differed substantially from seniors. Location of children's hospitals and local pediatric bed supply were associated with Medicare-pediatric divergence. There was little visual correspondence between the maps of traditional and pediatric-specific HSAs. CONCLUSION: Children and seniors have significantly different geographic patterns of hospitalization in California. Medicare-based HSAs may not be appropriate for all age groups and service types throughout the U.S

Craniofacial Structure, Aging and Dental Function: Their Relationships in Adult Human Skeletal Series

Five human skeletal series were examined to discern if post-adolescent aging, as measured by dental attrition, has significant effects on the morphometrics of the skull. Definite age-related changes were found in the crania of the European, Melanesian and Arikara Indian collections studied. A statistical approach unique to the subject area showed that both size and shape of the adult skull changed with age. Some of the more pronounced aging effects included forward projection of the face, widening of interorbital dimensions, flattening of the frontal bone in profile, retraction of the subnasal region relative to the zygomatic bones, and increases in orbit size and mastoid size. It was assumed that dental attrition not only reflected age, but also the cumulative dental functional forces exerted upon the cranium up to the time of death. Thus, after a consideration of craniofacial biomechanics, it became apparent that many of the age changes were probably direct responses to the aggregate forces of biting and chewing. The results provide support for the theory that some aspects of fossil hominid cranial morphology are adaptations to high levels of dental functional stress and strain. A good case is also made for the possibility that adult aging effects, regardless of their cause, can be a source of noise in some traditional kinds of craniometric investigations

Detection of Trace Elements/Isotopes in Olympic Dam Copper Concentrates by nanoSIMS

Many analytical techniques for trace element analysis are available to the geochemist and geometallurgist to understand and, ideally, quantify the distribution of trace and minor components in a mineral deposit. Bulk trace element data are useful, but do not provide information regarding specific host minerals—or lack thereof, in cases of surface adherence or fracture fill—for each element. The CAMECA nanoscale secondary ion mass spectrometer (nanoSIMS) 50 and 50L instruments feature ultra-low minimum detection limits (to parts-per-billion) and sub-micron spatial resolution, a combination not found in any other analytical platform. Using ore and copper concentrate samples from the Olympic Dam mining-processing operation, South Australia, we demonstrate the application of nanoSIMS to understand the mineralogical distribution of potential by-product and detrimental elements. Results show previously undetected mineral host assemblages and elemental associations, providing geochemists with insight into mineral formation and elemental remobilization—and metallurgists with critical information necessary for optimizing ore processing techniques. Gold and Te may be seen associated with brannerite, and Ag prefers chalcocite over bornite. Rare earth elements may be found in trace quantities in fluorapatite and fluorite, which may report to final concentrates as entrained liberated or gangue-sulfide composite particles. Selenium, As, and Te reside in sulfides, commonly in association with Pb, Bi, Ag, and Au. Radionuclide daughters of the 238U decay chain may be located using nanoSIMS, providing critical information on these trace components that is unavailable using other microanalytical techniques. These radionuclides are observed in many minerals but seem particularly enriched in uranium minerals, some phosphates and sulfates, and within high surface area minerals. The nanoSIMS has proven a valuable tool in determining the spatial distribution of trace elements and isotopes in fine-grained copper ore, providing researchers with crucial evidence needed to answer questions of ore formation, ore alteration, and ore processing

A new kind of invisible gold in pyrite hosted in deformation-related dislocations

Mining of “invisible gold” associated with sulfides in gold ores represents a significant proportion of gold production worldwide. Gold hosted in sulfide minerals has been proposed to be structurally bound in the crystal lattice as a sulfide-gold alloy and/or to occur as discrete metallic nanoparticles. Using a combination of microstructural quantification and nanoscale geochemical analyses on a pyrite crystal from an orogenic gold deposit, we show that dislocations hosted in a deformation low-angle boundary can be enriched in Ni, Cu, As, Pb, Sb, Bi, and Au. The cumulative trace-element enrichment in the dislocations is 3.2 at% higher compared to the bulk crystal. We propose that trace elements were segregated during the migration of the dislocation following the dislocation-impurity pair model. The gold hosted in nanoscale dislocations represents a new style of invisible gold