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Mike Walsh demonstrates how the technique of multiple regression analysis can be used to clarify the significance of several variables in determining the geographical factors which affect A&E attendance. The results indicate that travelling distance to A&E, social status of the catchment area and the proportion of the population in the 15-29 age group are significant factors in a complex equation.
A case-control study was conducted at Xinyang prefecture, Henan province in 1988 to investigate social, economic and geographic factors believed to be associated with the occurrence of residual falciparum malaria cases. Data were obtained from 65 residual cases and 195 matched control samples from neighbours, residents in the same village and extravillage. The questionnaire contained a total of 27 relevant items. The results of analysis of conditional logistic multi-regression model with IBM PC/XT microcomputer showed that six important risk factors related to residual falciparum malaria cases, i.e., the type of breeding places, yellow-brown soil, the knowledge of malaria transmission, open-sleep habit, family's malaria history and number of livestock. The epidemiological significance of these findings was discussed briefly.
The author collects the data of esophageal cancer mortality (1971-1973) of 78 counties in Hubei Province and the data of topography, climate, soil, rock formation and geochemical elements, including 40 suspected factors. The method of linear correlation and multiple stepwise regression are used for the comprehensive analysis of relation between the geographical factors and esophageal cancer. The result is that four factors metamorphic rock, zinc, copper, chromium are suspected factors. It suggests that the four factors will need future study.
Qualitative analyses were carried out of the thyroid hormones (T-3, T-4, and FT-4 indices) with a total of 380 pigs of the Camborough hybrid at the age of one to four months, raised at the nucleus base of a swine-breeding complex. Analyzed was the effect of the technologic regime, the geographic location of swine-breeding complexes, and the economic purpose of the animals on the quantitative changes in the indices studied. Based on the statistical analysis the reliable intervals of the physiologic values of the T-3, T-4, and FT-4 under the conditions of the individual complexes were found to be 0.52-0.82, 0.7-1.8: 0.62-1.1, 0.61-0.99, and 0.74-1.26; 5-12, 3.6-8.9, 3.16, 2.0-10.0, and 3.8-7.7 ng/100 ml; 0.60-1.3, 0.7-1.17, 0.69-1.18, 0.73-1.03, and 0.86-1.13.
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The multiple sclerosis (MS) mortality 1968-1977 in France, as reported by Alpérovitch and Bouvier, was tested for a possible correlation with a number of sociogeographic variables from relevant periods. The MS rate was associated with the main industry groups (metal processing and textile industry), with industry as a whole, and with the extent of oat cultivation. These findings are in agreement with observations in other countries and suggest a possible role of factors, somehow related to these features, in the etiology of MS.
BACKGROUND: We investigated whether risk factors for intracerebral hemorrhage (ICH) among indigenous Africans (IA) would vary in prevalence and effect compared with self-reported African, Hispanic, and White Americans by comparing data from 2 independent population-based case-control studies conducted in West Africa and the United States. METHODS: We compared ICH risk factors common to the SIREN (Stroke Investigative Research and Educational Network: 1100 case-control pairs) and the ERICH (Ethnic/Racial Variation of Intracerebral Hemorrhage: 999 case-control pairs African American participants, 998 case-control pairs, Hispanic Americans, 1000 case-control pairs, White Americans) studies. Ethnicity/Race was self-reported. The effect measure of interest is the odds ratio (OR). To test for differences in the effects of the risk factors between the SIREN IA study population and each of the ERICH study populations, a test for heterogeneity was computed using the R program, metagen (version 4.9-6). RESULTS: ICH occurred at a younger age among IA (54.3±13.4 years), African Americans (58.0±12.7), and Hispanic Americans (58.9±14.3), compared with White Americans (69.1±13.9). The largest distinction was for hypertension, where IA exhibited a much larger risk of ICH than the American study population (OR, 67.02 [95% CI, 33.30-134.85]), African American (OR, 3.71 [95% CI, 2.53-5.44]); Hispanic (OR, 3.55 [95% CI, 2.54-4.92]), and White population (OR, 2.69 [95% CI, 1.95-3.69]). Current alcohol use exhibited increased risk in IA (OR, 2.24 [95% CI, 1.36-3.67]), but not in African Americans (OR, 0.63 [95% CI, 0.46-0.86]), Hispanic (OR, 0.87 [95% CI, 0.65-1.17]), and White Americans (OR, 0.51 [95% CI, 0.38-0.69]). CONCLUSIONS: Identical or comparable risk factors do not consistently result in the same disease risk across different cultures and regions. Therefore, to improve our understanding of the genetic determinants and biological pathways driving ICH risk, it is crucial to study multiple populations, including IA, while accounting for the influence of environmental and social factors.
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Miners working in the North are exposed to more pronounced effects of unfavourable occupational factors (hand drillers, bulldozer operators, etc.) and are found to have higher morbidity rates. With their longer stay in the North, the incidence of gastrointestinal disorders increases. Among the migrants from the regions with contrasting climatic conditions. (Caucasus, Central Asia), the morbidity is higher than among those from other regions of this country.
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Interictal EEG records of Nigerian epileptic patients living in Lagos and clearly diagnosed as having grand mal epilepsy were compared with those of British epileptic patients with a similar diagnosis. Interictal EEG abnormalities (spike and wave discharges, (SW), photoparoxysmal discharges (PPD), and nonspecific changes) were significantly less common in Nigerian patients (incidence 15.7%) compared with British patients (incidence 52.9%) irrespective of age or sex of the patients. These findings may be related to ethnic or geographical factors. Rarity of PPD in Africans has previously been attributed to ethnic factors. Other studies have demonstrated an influence of geographical factors, specifically sunshine. In papio papio, such a geographical factor was shown to influence occurrence of PPD. In human epileptic subjects, environmental sunshine has been found to inversely influence the occurrence of PPD as well as SW. Besides possible ethnic factors, the relative rarity of interictal EEG abnormalities in Africans with grand mal epilepsy may be related to the larger amount of sunshine in the tropics.
In an effort to determine whether residence in a foreign country increases the risk of hepatitis B and C and cytomegalovirus (CMV) infection in United States (US) Armed Forces blood donors, 5719 volunteer donors at four US Navy blood banks were evaluated. Most participants were repeat donors (68%) and were young (mean age, 25 years), male (88%), and white (80%), black (10%), or Hispanic (7%). Birth outside of the United States was reported by 6 percent of subjects, and 34 percent had lived in a foreign country for more than 3 months. Twenty (0.3%) subjects had hepatitis B surface antigen (HBsAg), and 100 (1.7%) had antibody to hepatitis B core antigen (anti-HBc). Thirty-four (0.6%) were repeatably reactive in enzyme-linked immunosorbent assay for antibody to hepatitis C virus (anti-HCV); 11 (0.2%) had anti-HCV in immumoblot assay. Of the 3484 donors tested for anti-CMV, 1117 (32.1%) were positive. When demographic characteristics were controlled for both anti-HBc and anti-CMV seropositivies were independently associated in male blood donors with residence in the Philippines. Geographic factors were not associated with HBsAg and anti-HCV positivity. These findings indicate that the prevalence of serologic markers for viral hepatitis is low in military blood donors, but that residence in the Western Pacific is a risk factor for hepatitis B and CMV infection.
Hepatitis B hospitalization rates for US Army enlisted personnel were determined by occupation and geographic area for 1980. The only group in the US Army currently recommended to receive hepatitis B vaccine is medical personnel regularly exposed to blood. Other groups of Army personnel, specifically those working in areas of high hepatitis B endemicity, have been thought to be at higher risk. Therefore, this work was undertaken to document hospitalization rates for all personnel using occupational blood exposure criteria as well as geographic area of assignment as risk factors for hepatitis B. The hospitalization rates underestimate true rates of hepatitis B incidence by a wide margin, and therefore were not used to calculate specific costs and specific benefits for a new vaccination strategy. In spite of this limitation, these data were useful for calculating relative risk, attributable risk, and amount of vaccine preventable disease. The risk of hospitalization for blood-exposed employees was consistently higher than that for non-blood-exposed personnel. The magnitude of the relative risk for blood exposure may be as high as 3.8 times or as low as 1.2 times, depending on which occupational comparison group is used. The relative risk of hospitalization in South Korea vs. the United States was 3.1 (p less than 0.0001), that for Europe vs. the United States, 2.1 (p less than 0.0001). Of all occupational and geographic risk comparisons, assignment to South Korea carried the highest attributable risk: 225 per 100,000. The amount of vaccine preventable disease in personnel assigned to South Korea was similar to that in occupationally blood-exposed employees (5.5 vs. 5.2 hospitalized cases per 1,000 vaccinees) after prorating exposure to risk based on average number of days of exposure to risk over three years. These data support the argument that geographic factors are as important as occupational blood exposure in defining risk of hepatitis B hospitalization among the US Army enlisted personnel.
Previous studies have indicated that infection rates of Helicobacter pylori are influenced by geographical factors. The present studies evaluate the characteristics of gastritis, associated with infection by H. pyrlori, and demonstrate relationships between different geographical locations and the extent of inflammatory cell accumulation in the gastric mucosa. Gastric biopsy specimens were obtained from patients infected with H. pylori at three clinical sites (two from North America and one from South America). Gastric inflammation was evaluated by quantitative histomorphometric techniques. Patients from South America had a more severe gastritis than did those from North America. Additionally, in South American patients the neutrophil was the predominant inflammatory cell type in the gastric mucosa. In contrast, the lymphocyte was the primary cell composing the mucosal infiltrate of infected North American subjects. Eosinophil infiltration into the mucosa correlated with the extent of mucosal atrophy; however, there were no differences between the North and South American patient populations in the extent of mucosal atrophy present in the specimens. We conclude that the characteristics (severity and cell type) of gastritis associated with infection by H. pylori are influenced by geographical factors that may be similar to those that modify infection rates for different geographical locations.