Higher US Rural Mortality Rates Linked To Socioeconomic Status, Physician Shortages, And Lack Of Health Insurance.

All-cause mortality rates in rural areas have exceeded those in urban areas of the US since the 1980s, and the gap continues to widen. Yet no definitive causes of this difference are known, and within-state differences that might be amenable to state-level policy have not been explored. An analysis of 2016 state-level data indicated that rural mortality exceeded urban mortality in all but three states, with substantial variability in both rates across states. Overall, higher rural mortality at the state level can be mainly explained by three factors: socioeconomic deprivation, physician shortages, and lack of health insurance. To a certain degree, these factors reflect a state's health policies, such as expansion of eligibility for Medicaid, health infrastructure, and socioeconomic conditions. Our findings suggest that state and federal policy efforts to address rural-urban disparities in these areas could alleviate the higher rates of all-cause mortality faced by rural US residents.

The Health Insurance Gap After Implementation of the Affordable Care Act in Texas.

Households with incomes between 18% and 99% of the federal poverty level (FPL) are ineligible for Medicaid or enrollment in the health insurance exchange marketplace in Texas, resulting in the health insurance gap. We sought to determine the number of non-elderly adult Texans (NEATs) aged between 18 and 64 years in the insurance gap in rural vs urban areas in East Texas, West Texas, and South Texas. Data were obtained from the US Census Bureau website. In 2014, there were 1,101,000 NEATs in the insurance gap, accounting for 24.5% of all uninsured persons in Texas. The gap was significantly higher in rural vs urban areas in East and South Texas and in Texas as a whole. Large coverage gaps in states like Texas not expanding Medicaid under the Affordable Care Act pose major hurdles to reducing the number of uninsured individuals in these states.

Enrollment in Health Insurance Through the Marketplace After Implementation of the Affordable Care Act in Texas.

One of the goals of the Affordable Care Act aims to provide affordable health insurance through the health insurance exchange marketplace (the Marketplace). This study explores enrollments in the Marketplace in Texas and in rural vs urban areas in the East, South, and West regions of the state. Data are derived from the US Census Bureau and the Department of Health and Human Services. A total of 92.7% of eligible non-elderly adult Texans (NEATs) had enrolled in Marketplace insurance as of February 2015. Rural residents were less likely than urban residents to use the Marketplace. Most enrollees (85%) had received tax credits, and 58.6% had received cost-sharing reductions. The number of uninsured NEATs was reduced by 710,000 by 2014, which is equivalent to two-thirds of the enrollees in the Marketplace. One-third of the enrollees previously had private or employer-based insurance before enrollment into the Marketplace.

Association of hypothyroidism with low-level arsenic exposure in rural West Texas.

It has been reported recently that a higher airborne arsenic level was correlated with higher urinary arsenic concentration and lower serum thyroxin level among urban policemen and rural highway workmen in Italy. The current study was to determine whether exposure to low-level arsenic groundwater (2-22µg/L) is associated with hypothyroidism among 723 participants (118 male and 267 female Hispanics; 108 male and 230 female non-Hispanic whites, NHW) living in rural West Texas counties. Arsenic and iodine levels in their groundwater used for drinking and or cooking were estimated by the inverse distance weighted (IDW) interpolation technique. Groundwater arsenic was ≥8µg/L in 36% of the subjects' wells while iodine concentration was <1µg/L in 91% of their wells. Logistic regression analysis showed that arsenic in groundwater ≥8µg/L and cumulative arsenic exposure (groundwater arsenic concentration multiplied by the number of years living in the current address) but not groundwater iodine concentration were significant predictors for hypothyroidism among Hispanics (p<0.05) but not NHW after adjusting for covariates such as age, gender, annual household income and health insurance coverage. The ethnic difference may be due to a marginally higher percentage of Hispanics (p=0.0622) who lived in areas with groundwater arsenic ≥8µg/L compared with NHW. The prevalence of hypothyroidism was significantly higher in Hispanics or NHW of this rural cohort than the national prevalence. Measures should be taken to reduce arsenic in drinking water in order to prevent hypothyroidism in rural areas.

The impact of rural health care accessibility on cancer-related behaviors and outcomes.

BACKGROUND: This research seeks to identify the relationship between economic factors related to the ability to receive and pay for health services and adverse cancer outcomes, as well as preventative screening and behavioral factors that influence the risk of cancer. We focus on the Northern High Plains region, where we are able to compare regions with extremely low access to health services with those with relatively high levels of access. OBJECTIVE: This study aims to identify health disparities in rural communities, particularly among Native American populations, and, thereby, begin to determine the most effective means by which to deliver health services to areas where geography, economics, and culture might prevent traditional models of health delivery from providing sufficient incentives for the prevention of adverse cancer-related outcomes. METHODS: The Health Care Accessibility Index (HCAI) is computed through the use of principal component analysis and includes economic variables as well as variables concerning institutional and geographic access to health care. Index values are then regressed onto cancer outcomes, cancer-prevention outcomes, and cancer-related risk, using weighted least squares and quantile regressions. RESULTS: Counties with relatively poor access to health care (low HCAI) also have statistically (1) lower breast cancer screening rates, (2) higher smoking prevalence, (3) higher obesity prevalence, and (4) higher cancer-related mortality rates. Breast cancer screening is found to be especially sensitive to areas of low health accessibility. CONCLUSIONS: Empirical results provide support for policy efforts to increase the accessibility of health care services that are targeted to areas with low mammography screening rates, high obesity rates, high smoking prevalence, as well as areas near Native American reservation territories.

Arsenic exposure, AS3MT polymorphism, and neuropsychological functioning among rural dwelling adults and elders: a cross-sectional study.

BACKGROUND: The aim was to examine the link between low-level arsenic exposure and cognitive functioning, and the potential role of a single nucleotide polymorphism (SNP A35991G, rs10748835) of the AS3MT gene in modifying this link. METHODS: Data were analyzed on 526 participants from Project FRONTIER. Hierarchical linear regressions were created with neuropsychological raw index scores as the outcome variable and arsenic exposure and AS3MT SNP as different predictor variables. RESULTS: Within the total sample, arsenic exposure was negatively associated with language (p < 0.001) and executive functioning (p < 0.001). Among those with the AA genotype of the AS3MT gene, arsenic levels were negatively associated with language (p < 0.001), attention (p = 0.01), and executive functioning (p = 0.04). Among those with the AG genotype, arsenic levels were positively associated with immediate (p = 0.04) and delayed memory (p < 0.001) and negatively associated with executive functioning (p = 0.03). Among those with the GG genotype, arsenic levels were negatively associated with visuospatial functioning (p = 0.02). CONCLUSIONS: Low-level arsenic exposure is associated with cognitive functioning; however, this association is modified by an AS3MT gene.

Comparison of the accuracy of kriging and IDW interpolations in estimating groundwater arsenic concentrations in Texas.

Exposure to arsenic causes many diseases. Most Americans in rural areas use groundwater for drinking, which may contain arsenic above the currently allowable level, 10µg/L. It is cost-effective to estimate groundwater arsenic levels based on data from wells with known arsenic concentrations. We compared the accuracy of several commonly used interpolation methods in estimating arsenic concentrations in >8000 wells in Texas by the leave-one-out-cross-validation technique. Correlation coefficient between measured and estimated arsenic levels was greater with inverse distance weighted (IDW) than kriging Gaussian, kriging spherical or cokriging interpolations when analyzing data from wells in the entire Texas (p<0.0001). Correlation coefficient was significantly lower with cokriging than any other methods (p<0.006) for wells in Texas, east Texas or the Edwards aquifer. Correlation coefficient was significantly greater for wells in southwestern Texas Panhandle than in east Texas, and was higher for wells in Ogallala aquifer than in Edwards aquifer (p<0.0001) regardless of interpolation methods. In regression analysis, the best models are when well depth and/or elevation were entered into the model as covariates regardless of area/aquifer or interpolation methods, and models with IDW are better than kriging in any area/aquifer. In conclusion, the accuracy in estimating groundwater arsenic level depends on both interpolation methods and wells' geographic distributions and characteristics in Texas. Taking well depth and elevation into regression analysis as covariates significantly increases the accuracy in estimating groundwater arsenic level in Texas with IDW in particular.

Socioeconomic deprivation as a determinant of cancer mortality and the Hispanic paradox in Texas, USA.

INTRODUCTION: We have recently reported that delayed cancer detection is associated with the Wellbeing Index (WI) for socioeconomic deprivation, lack of health insurance, physician shortage, and Hispanic ethnicity. The current study investigates whether these factors are determinants of cancer mortality in Texas, the United States of America (USA). METHODS: Data for breast, colorectal, female genital system, lung, prostate, and all-type cancers are obtained from the Texas Cancer Registry. A weighted regression model for non-Hispanic whites, Hispanics, and African Americans is used with age-adjusted mortality (2004-2008 data combined) for each county as the dependent variable while independent variables include WI, percentage of the uninsured, and physician supply. RESULTS: Higher mortality for breast, female genital system, lung, and all-type cancers is associated with higher WI among non-Hispanic whites and/or African Americans but with lower WI in Hispanics after adjusting for physician supply and percentage of the uninsured. Mortality for all the cancers studied is in the following order from high to low: African Americans, non-Hispanic whites, and Hispanics. Lung cancer mortality is particularly low in Hispanics, which is only 35% of African Americans' mortality and 40% of non-Hispanic whites' mortality. CONCLUSIONS: Higher degree of socioeconomic deprivation is associated with higher mortality of several cancers among non-Hispanic whites and African Americans, but with lower mortality among Hispanics in Texas. Also, mortality rates of all these cancers studied are the lowest in Hispanics. Further investigations are needed to better understand the mechanisms of the Hispanic Paradox.

Association of the optic disc structure with the use of antihypertensive medications: the thessaloniki eye study.

PURPOSE: To investigate the association of antihypertensive medications with optic disc structure by blood pressure (BP) level, in nonglaucoma subjects. DESIGN: Cross-sectional, population-based study. METHODS: A subset of Thessaloniki Eye Study participants was included in this study. Subjects were interviewed for medical history and underwent extensive ophthalmic examination, BP measurement, and optic disc imaging with the Heidelberg retinal tomograph. Subjects treated for hypertension were grouped in the following groups: (1) angiotensin-converting enzyme inhibitors and/or angiotensin-receptor blockers; (2) beta blockers and/or calcium-channel blockers; (3) diuretics alone or combined with others; and (4) other combinations. Cup size and cup-to-disc (C/D) ratio in the above groups were compared with the untreated group, using regression models. Analyses were rerun for subjects with systolic BP (SBP)<140 mm Hg, SBP≥140 mm Hg, diastolic BP (DBP)<90 mm Hg, and DBP≥90 mm Hg. RESULTS: Among 232 subjects, 131 were receiving antihypertensive medications. In subjects with DBP<90 mm Hg, all medications groups were associated with larger cup size and higher C/D ratio compared with the untreated group. Results were similar in subjects with SBP<140 mm Hg, with the exception of the beta blockers and/or calcium-channel blockers group. None of the medications groups were associated with the Heidelberg retinal tomograph parameters in those with DBP≥90 mm Hg or SBP≥140 mm Hg. CONCLUSIONS: All classes of antihypertensive medications were associated with larger cup size and higher C/D ratio in subjects with either DBP<90 mm Hg or SBP<140 mm Hg. These results suggest that there is no specific medication-related effect on optic disc structure, and the associations found are mediated through the hypotensive effect of antihypertensive medications.

Determinants of delayed detection of cancers in Texas counties in the United States of America.

INTRODUCTION: Previous studies have shown that delayed detection of several cancers is related to socioeconomic deprivation as measured by the Wellbeing Index (WI) in Texas, the United States of America (USA). The current study investigates whether delayed cancer detection is related to lack of health insurance, physician shortage and higher percentages of Hispanics rather than WI per se since these factors are directly related to delayed cancer detection and may confound WI. METHODS: Cancer data and potential determinants of delayed cancer detection are derived from Texas Cancer Registry, Texas State Data Center, and Texas Department of State Health Services and U.S. Census Bureau. Texas cancer data from 1997 to 2003 are aggregated to calculate age-adjusted late- and early-stage cancer detection rates. The WI for each county is computed using data from the USA Census 2000. A weighted Tobit regression model is used to account for population size and censoring. The percentage of late-stage cancer cases is the dependent variable while independent variables include WI and the aforementioned potential confounders. RESULTS: Delayed detection of breast, lung, colorectal and female genital cancers is associated with higher percentage of uninsured residents (p < 0.05). Delayed detection is also associated with physician shortage and lower percentages of Hispanics for certain cancers ceteris paribus ( p < 0.05). The percentage of late-stage cases is positively correlated with WI for lung, and prostate cancers after adjusting for confounders ( p < 0.05). CONCLUSIONS: The percentages of uninsured and Hispanic residents as well as physician supply are determinants of delayed detection for several cancers independently of WI, and vice versa. Identification of these determinants provides the evidence-base critical for decision makers to address specific issues for promoting early detection in effective cancer control.

Low-level arsenic exposure, AS3MT gene polymorphism and cardiovascular diseases in rural Texas counties.

Most Americans living in rural areas use groundwater for drinking. Exposure to low-level (around the current U.S. standard 10 µg/L) arsenic in drinking water is associated with increased mortality of cardiovascular diseases. The current study was to determine if coronary heart disease, hypertension, and hyperlipidemia were associated with low-level arsenic exposure and AS3MT gene single nucleotide polymorphism (SNP) A35991G (rs10748835) in rural Texas. Subjects (156 men, 343 women, 40-96 years of age with a mean of 61) were residents from rural counties Cochran, Palmer, and Bailey, Texas. Groundwater arsenic concentration at each subject's home was estimated with ArcGIS inverse distance weighted interpolation based on the residential location's distances to surrounding wells with known water arsenic concentrations. The estimated groundwater arsenic concentration ranged from 2.2 to 15.3 (mean 6.2) µg/L in this cohort. Logistic regression analysis showed that coronary heart disease was associated with higher arsenic exposure (p<0.05) and with AS3MT genotype GG vs. AA (p<0.05) after adjustments for age, ethnicity, gender, education, smoking status, alcoholism, and anti-hyperlipidemia medication. Hypertension was associated with higher arsenic exposure, while hyperlipidemia was associated with genotype AG vs. AA of the AS3MT gene (p<0.05). Thus, coronary heart disease and its main risk factors were associated with low-level arsenic exposure, AS3MT polymorphism or both.

Low-level groundwater arsenic exposure impacts cognition: a project FRONTIER study.

Arsenic is a ubiquitous environmental toxin with known neurological consequences. Few studies, however, have investigated groundwater arsenic concentrations and cognition among adults and elders. In the study described in this article, the authors examined the potential link between cognitive functioning and low concentrations of arsenic in drinking water. Arsenic concentrations were estimated by the Geographic Information System approach (GIS-arsenic) for 299 rural-dwelling adults and elders. Cognition was assessed with Folstein Mini-Mental State Examination (MMSE). Those in the relatively high GIS-arsenic exposure (> 10.0 microg/L) group had significantly lower MMSE scores than those in the low GIS-arsenic exposure (< or = 10.0 microg/L) group (p < .03). The number of years of education was significantly lower in those in the high GIS-arsenic group(s) than in those in the low GIS-arsenic group (p < .05). These results suggest that poorer cognitive functioning and lower education levels were associated with higher (though still low-level) GIS-arsenic levels in this rural adult cohort.

Long-term low-level arsenic exposure is associated with poorer neuropsychological functioning: a Project FRONTIER study.

Exposure to elements in groundwater (toxic or beneficial) is commonplace yet, outside of lead and mercury, little research has examined the impact of many commonly occurring environmental exposures on mental abilities during the aging process. Inorganic arsenic is a known neurotoxin that has both neurodevelopmental and neurocognitive consequences. The aim of this study was to examine the potential association between current and long-term arsenic exposure and detailed neuropsychological functioning in a sample of rural-dwelling adults and elders. Data were analyzed from 434 participants (133 men and 301 women) of Project FRONTIER, a community-based participatory research study of the epidemiology of health issues of rural-dwelling adults and elders. The results of the study showed that GIS-based groundwater arsenic exposure (current and long-term) was significantly related to poorer scores in language, visuospatial skills, and executive functioning. Additionally, long-term low-level exposure to arsenic was significantly correlated to poorer scores in global cognition, processing speed and immediate memory. The finding of a correlation between arsenic and the domains of executive functioning and memory is of critical importance as these are cognitive domains that reflect the earliest manifestations of Alzheimer's disease. Additional work is warranted given the population health implications associated with long-term low-level arsenic exposure.

Correlation of the ratio of metastatic to non-metastatic cancer cases with the degree of socioeconomic deprivation among Texas counties.

BACKGROUND: Previous studies have demonstrated that cancer registrations and hospital discharge rate are closely correlated with census data-based socioeconomic deprivation indices. We hypothesized that communities with higher degrees of socioeconomic deprivation tend to have a higher ratio of metastatic to non-metastatic cancer cases (lung, breast, prostate, female genital system, colorectal cancers or all types of cancers combined). In this study, we investigate the potential link between this ratio and the Wellbeing Index (WI) among Texas counties. RESULTS: Cancer data in 2000 were provided by the Texas Cancer Registry, while data on the ten socioeconomic variables among the 254 Texas counties in 2000 for building the WI were obtained from U.S. Census Bureau. The ten socioeconomic status variables were subjected to the principal component analysis, and the first principal component scores were grouped into deciles for the WI (1 to 10) and the 254 Texas counties were classified into 10 corresponding groups. Weighted linear regression analyses and a Cochran-Armitage trend test were performed to determine the relationship between the ratio of age-adjusted metastatic to non-metastatic cancer incidence cases and WI. The ratios of metastatic to non-metastatic cases of female genital system cancer (r2 = 0.84, p = 0.0002), all-type cancers (r2= 0.73, p = 0.0017) and lung cancer (r2= 0.54, p = 0.0156) at diagnosis were positively correlated with WI. CONCLUSIONS: The ratios of metastatic to non-metastatic cases of all-type, female genital system and lung cancers at diagnosis were statistically correlated with socioeconomic deprivation. Potential mediators for the correlation warrant further investigation in order to reduce health disparities associated with socioeconomic inequality.

The arsenic exposure hypothesis for Alzheimer disease.

Prior research has shown that arsenic exposure induces changes that coincide with most of the developmental, biochemical, pathologic, and clinical features of Alzheimer disease (AD) and associated disorders. On the basis of this literature, we propose the Arsenic Exposure Hypothesis for AD that is inclusive of and cooperative with the existing hypotheses. Arsenic toxicity induces hyperphosphorylation of protein tau and overtranscription of the amyloid precursor protein, which are involved in the formation of neurofibrillary tangles and brain amyloid plaques, consistent with the amyloid hypothesis of AD. Arsenic exposure has been associated with cardiovascular diseases and associated risk factors, which is in agreement with the vascular hypothesis of AD. Arsenic exposure invokes brain inflammatory responses, which resonates with the inflammatory hypotheses of AD. Arsenic exposure has been linked to reduced memory and intellectual abilities in children and adolescents, which provides a biologic basis for the developmental origin of health and disease hypothesis for AD. Arsenic and its metabolites generate free radicals causing oxidative stress and neuronal death, which fits the existing oxidative stress hypothesis. Taken together, the arsenic exposure hypothesis for AD provides a parsimonious testable hypothesis for the development and progression of this devastating disease at least for some subsets of individuals.

Trend and racial disparities in infant mortality rate in Texas from 1990 to 2004.

PURPOSE: To determine the trend and disparities in infant mortality rate (IMR) from 1990 to 2004 in Texas, which is one of the few states with severe physician shortage in the United States. METHODS: Trend analysis and Poisson regression were performed with data from Texas Department of State for Health Services and other Web sites. RESULTS: IMR decreased from 1990 to 2000 followed by a trend of increase from 2000 to 2004 in Texas. The recent trend of increase in IMR was observed in all ethnic groups. IMR was associated with ethnicity, area of residence in Texas (rural vs urban areas in east vs south vs west), median income index, and primary care physician supply (primary care physician to population ratio). IMR in blacks was more than 2 times that of other ethnic groups, and the gap had been increasing since 1997. The recent increasing trend in IMR coincided with a decreasing trend in primary care physician supply and a decrease or a slower increase in median income index. CONCLUSIONS: IMR increased in recent years, particularly in African Americans in Texas. Measures should be taken to reverse the worsening trend in IMR and to reduce regional and racial disparities.

Family information service participation increases the rates of mutation testing among members of families with BRCA1/2 mutations.

Some members of hereditary breast-ovarian cancer (HBOC) families may not participate in BRCA testing to determine their mutation status in part because they are unaware of their cancer risk and the availability of BRCA testing. Participation in a family information service (FIS), of which we have provided more than 100 sessions during the past 30 years, has been seen to effectively allow family members to be educated regarding their cancer genetic risk and potential benefits from cancer control measures such as mutation testing. However, the effect of the FIS on the rate of mutation testing has not been studied. One thousand five hundred seventy-four eligible (>18-year old, at a 25% or higher pedigree risk) members from 60 extended HBOC families with BRCA1/2 mutations were invited to attend a FIS to learn about their risk and undergo genetic testing. The rates of mutation testing were compared between those who had attended an FIS, and those who had not with chi-squared test and logistic regression analysis. Seventy five percent (334/444) of FIS attendees had undergone mutation testing following or during an FIS which was significantly higher than the 33.8% (382/1130) rate among nonattendees (p < 0.0001). Logistic regression analysis showed that FIS attendance, breast-ovarian cancer history, gender, and age were significant variables for undertaking a mutation test. FIS attendance significantly increased the rate of mutation testing among high-risk family members.

Ethical, legal and social issues of genetic studies with African immigrants as research subjects.

There is growing interest in exploring gene-environment interactions in the etiology of diseases in immigrants from sub-Saharan Africa. Our experience working with the Sudanese immigrant population in Omaha, NE, makes clear the pressing need for geneticists and federal and local funding agencies to address the ethical, legal and social implications of genetic research with such vulnerable populations. Our work raises several questions. How does one design research with African immigrant participants to assure it is ethical? Many immigrants may not understand the purposes, risks and benefits involved in research because of low literacy rates, one of the results of civil wars, or concepts of biologic science foreign to their cultures. Is it possible to obtain truly informed consent? Do African immigrants perceive genetic research using them as subjects as racist? Is genetic research on minorities "biopiracy" or "bio-colonialism?" In our experience, some Sudanese immigrants have challenged the legality and ethics of genetic studies with profit-making as an end. We have concluded that it is essential to educate African immigrant or any other non-English-speaking immigrant participants in research using lay language and graphic illustrations before obtaining consent. Cultural proficiency is important in gaining the trust of African immigrants; profit-sharing may encourage their participation in genetic research to benefit all; involvement of African immigrant community leaders in planning, delivery and evaluation using the community-based participatory research approach will facilitate healthcare promotion, health literacy education, as well as genetic research. It is crucial to address the ethical, legal and social implications of genetic studies with African immigrants as research subjects.

Origins and prevalence of the American Founder Mutation of MSH2.

Large germline deletions within the mismatch repair gene MSH2 account for a significant proportion (up to 20%) of all deleterious mutations of this gene which are associated with Lynch syndrome. An exons 1 to 6 deletion of MSH2, originally reported in nine families, has been associated with a founding event within the United States, which genealogic studies had previously dated to 1727, and the number of present day carriers was estimated to be 18,981. Here, we report the development of a robust multiplex PCR which has assisted in the detection of 32 new families who carry the MSH2 American Founder Mutation (AFM). By offering testing to family members, 126 carriers of the AFM have been identified. Extensive genealogic studies have connected 27 of the 41 AFM families into seven extended pedigrees. These extended families have been traced back to around the 18th century without any evidence of further convergence between them. Characterization of the genomic sequence flanking the deletion and the identification of a common disease haplotype of between 0.6 and 2.3 Mb in all probands provides evidence for a common ancestor between these extended families. The DMLE+2.2 software predicts an age of approximately 500 years (95% confidence interval, 425-625) for this mutation. Taken together, these data are suggestive of an earlier founding event than was first thought, which likely occurred in a European or a Native American population. The consequences of this finding would be that the AFM is significantly more frequent in the United States than was previously predicted.

Factors associated with undiagnosed open-angle glaucoma: the Thessaloniki Eye Study.

PURPOSE: To identify factors associated with undiagnosed open-angle glaucoma (OAG), primary open-angle glaucoma (POAG), and pseudoexfoliative glaucoma (PEXG) in an elderly population in Thessaloniki, Greece. DESIGN: Cross-sectional population-based study. METHODS: Randomly selected subjects > or =60 years (n = 2,554) participated in the study. Subjects were classified as having POAG or PEXG according to specific criteria and using a two-scale definition of glaucoma. Undiagnosed glaucoma was defined as absence of either prior diagnosis of glaucoma or ocular hypertension or prior medical treatment for glaucoma or prior glaucoma surgery. Logistic regression analyses were performed with age, gender, family history of glaucoma, history of cataract surgery, visual acuity, vertical cup-to-disk (C/D) ratio, intraocular pressure, Advanced Glaucoma Intervention Study visual field score, time since last eye doctor visit, and type of OAG as covariates. RESULTS: The prevalence of undiagnosed glaucoma was 57.1% (56/98) for POAG, significantly higher than the prevalence of 34.9% (15/43) for PEXG (P = .017). POAG patients presented three to four times increased risk to be undiagnosed compared with PEXG patients (P = .02 and P = .04, respectively). Patients with OAG who had not visited an ophthalmologist during the last year had six times an increased risk to be undiagnosed (P = .003). In POAG, smaller vertical C/D ratio was statistically significantly associated with an increased risk to be undiagnosed (P = .008). CONCLUSIONS: Lack of regular visits to an ophthalmologist was a major factor for undiagnosed OAG. POAG was more likely to be undiagnosed than PEXG. Since C/D ratio was associated with undiagnosed POAG, standardized protocols involving thorough evaluation of the optic disk are recommended for ophthalmologists.