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PubMed1992

The roles of ecological and evolutionary influences in providing structure to parasite species assemblages.

Parasite species assemblages currently are thought to range from isolationist to interactive, their dynamic properties being related to the number of species and types of hosts involved. The literature contains few experimental tests of this concept, however, and many of the host/parasite systems studied to date are not amenable to experimental manipulation. In this review, the presence of a parasite species, in a sample of host individuals, is considered to be an evolutionary phenomenon, but the parasite's population structure is considered to be an ecological one. Studies that allow evaluation of these 2 influences are comparative in nature and include data from a series of homogeneous samples of host populations. A lottery model is presented, in which hosts acquire their assemblages of parasites by Monte Carlo type sampling from multiple kind arrays; the major structuring influence is the relative probability of becoming infected by various parasite species. Claims of parasite species interaction need to be supported by studies showing departures from the predictions of this model. The species density and infraassemblage diversity index distributions are recommended as quantitative tools useful in such work.

Animals↗
PubMed1995

Increase in incidence of insulin-dependent diabetes mellitus among children in Finland.

BACKGROUND: In Finland, the incidence of insulin-dependent diabetes mellitus (IDDM) in children aged < 15 years is the highest in the world. The aim of this study was to determine the temporal variation in incidence and the age distribution at diagnosis of IDDM. SUBJECTS AND METHODS: Data on incidence of IDDM in Finland nationwide were obtained from two sources: the Central Drug Registry for the years 1965-1986 (6195 IDDM cases) and the prospective IDDM registry for the years 1987-1992 (2062 IDDM cases). The annual incidence rates were calculated per 100,000 population. The increase in incidence from 1965 to 1992 was estimated by fitting the linear regression with the annual incidence data. RESULTS: The overall incidence of IDDM between 1987 and 1992 was 36 per 100,000/year. During 1965-1992 the increase was almost linear. The regression-based change in incidence was 2.8% per year. In the 1970s the increase in incidence was steepest in 5-9 year olds and since the mid-1980s in those < 5 years old at diagnosis. CONCLUSIONS: The incidence of IDDM in Finnish children seems to increase further. During the last decades the increase in incidence has been almost linear with occasional peaks. The age-at-diagnosis of IDDM has been moving towards the younger ages, and differences in incidence between age groups have now almost disappeared among Finnish children aged 1-14 years.

Adolescent↗
PubMed1998

Incidence of invasive cancers following basal cell skin cancer.

To obtain quantitative information on the risk of invasive cancers following a diagnosis of basal cell carcinoma (BCC) of the skin, patients with incident BCC cases listed in the cancer registries of the Swiss cantons of Vaud and Neuchâtel between 1974 and 1994 were actively followed up through December 31, 1994, for the occurrence of subsequent invasive neoplasms. Among 11,878 persons with incident BCC who were followed for a total of 76,510 person-years at risk, 1,543 metachronous cancers were observed versus 1,397.9 expected, corresponding to a standardized incidence ratio (SIR) of 1.1 (95% confidence interval (CI) 1.0-1.2). However, after exclusion of skin cancers (mostly squamous cell carcinoma and melanoma), 975 second primary cancers were observed versus 1,059 expected (SIR = 0.9, 95% CI 0.8-1.0). Significant excesses were registered for cancer of the lip (SIR = 2.2), for squamous cell skin cancer (SIR = 4.5) and melanoma of the skin (SIR = 2.5), and for non-Hodgkin's lymphoma (SIR = 1.9). The SIRs were also above unity, though not significantly, for cancers of the salivary glands (SIR = 2.8) and the small intestine (SIR = 2.1) and for soft-tissue sarcomas (SIR = 1.7). The SIR for lung cancer was 0.9. The SIRs for salivary gland and skin cancer were appreciably greater below age 70 years. For most sites, particularly for squamous cell cancer and melanoma of the skin, the SIRs remained elevated 5 or more years after BCC diagnosis. The cumulative incidence of squamous cell skin cancer was 13% at 19 years; this stresses the importance of carefully monitoring skin lesions among persons previously diagnosed with BCC.

Adult↗
PubMed1996

Long-term trends in incidence of and mortality from acute myocardial infarction and stroke in women: Analyses of total first events and of deaths in the Uppsala Health Care Region, Sweden.

We studied the trends from 1969 to the mid-1980s in the incidence and mortality of acute myocardial infarction and stroke in Swedish women residing in the Uppsala Health Care Region. We used data from the Inpatient Care and Causes of Death registers to obtain total first event incidence and mortality rates. In our population, there were 20,182 acute myocardial infarctions and 30,462 stroke events, and 17,359 and 21,336 deaths, respectively. We found an average overall annual increase of 1.3% in the age-standardized incidence of acute myocardial infarction during the 1970s, followed by decreasing rates during the early 1980s. Mortality was virtually unchanged. Notably, among women 45-49 years of age, we observed a rising trend during the whole period, whereas in the oldest age groups, the increase slowed and reversed in the latter years. Both the incidence and mortality for stroke declined steadily: the age-standardized incidence fell by an average of 2.1% per year for all stroke and 7.8% for intracerebral hemorrhage. The falling rate of stroke was best explained by birth cohort effects, with a 30% reduction in women born in 1920 and later as compared with those born in 1890. We conclude that important changes in Swedish women's cardiovascular health have taken place and that increasing cigarette smoking and hypertensive treatment are major determinants.

Adult↗
PubMed2004

Risk of non-Hodgkin's lymphoma and skin malignancies in patients diagnosed with cataract.

The rapid increase of non-Hodgkin's lymphoma (NHL) in industrialized countries is yet unexplained. Ultraviolet radiation (UVR) has been suggested as an aetiologic factor due to observed elevated risks of cutaneous malignancies after NHL and vice versa. Cataract, as related to UVR, was tested as a proxy variable to further elucidate this observation. Cataract in-patients (n = 49914) reported to the Swedish Patient Register and later developing NHL and cutaneous malignancies were identified by record linkage to the Swedish Cancer Registry. The observed number of malignancies among cataract patients did not differ significantly from that expected in the general population. In contrast, the risk of cutaneous malignant melanoma was lower than anticipated, based on Swedish background incidence figures. The results did not give support for a causal relationship between NHL and UVR.

Age Distribution↗
PubMed2003

Changes in deaths reported with human immunodeficiency virus infection among United States children less than thirteen years old, 1987 through 1999.

BACKGROUND: With implementation of highly active antiretroviral therapy during 1995 through 1999, deaths reported in adults with HIV infection decreased 67%, and the proportions of those accompanied by various opportunistic infections decreased, whereas their proportions with possibly unrelated conditions (e.g. diseases of liver, kidneys and heart) increased. OBJECTIVE: To examine changes among deaths of children with HIV infection. METHODS: We analyzed multiple-cause death certificate data with any mention of HIV infection for all US deaths at ages <13 years from 1987 through 1999. We examined changes in the numbers and rates of deaths and the proportions reported with various diseases. RESULTS: The annual number of children who died with HIV infection increased from 274 in 1987 to 511 in 1994 and then decreased by 81% to 97 in 1999. The median age at death increased from 1 year in 1987 to 5 years in 1999. During the periods 1987 through 1991 (1652 deaths), 1992 through 1995 (1906 deaths) and 1996 through 1999 (762 deaths), the proportion of deaths with pneumocystosis decreased from 19.0% to 9.9% and 7.5%, respectively. In a comparison of 1992 through 1995 with 1996 through 1999, no significant change occurred in the proportions of deaths with nontuberculous mycobacteriosis (5.6% to 6.0%), cytomegalovirus disease (3.2% to 4.4%), heart disease (10.8% to 11.7%), kidney disease (5.0%), liver disease (3.9% to 4.1%) or wasting/cachexia (4.0% to 5.0%). CONCLUSIONS: Deaths with HIV infection among children have decreased substantially, probably because of both highly active antiretroviral therapy and prevention of perinatal HIV transmission. The decrease after 1995 was greater proportionally among children than among adults, but fewer changes in disease proportions occurred among children.

Adolescent↗
PubMed2006

Validation of the potentially avoidable hospital readmission rate as a routine indicator of the quality of hospital care.

BACKGROUND: The hospital readmission rate has been proposed as an important outcome indicator computable from routine statistics. However, most commonly used measures raise conceptual issues. OBJECTIVES: We sought to evaluate the usefulness of the computerized algorithm for identifying avoidable readmissions on the basis of minimum bias, criterion validity, and measurement precision. RESEARCH DESIGN AND SUBJECTS: A total of 131,809 hospitalizations of patients discharged alive from 49 hospitals were used to compare the predictive performance of risk adjustment methods. A subset of a random sample of 570 medical records of discharge/readmission pairs in 12 hospitals were reviewed to estimate the predictive value of the screening of potentially avoidable readmissions. MEASURES: Potentially avoidable readmissions, defined as readmissions related to a condition of the previous hospitalization and not expected as part of a program of care and occurring within 30 days after the previous discharge, were identified by a computerized algorithm. Unavoidable readmissions were considered as censored events. RESULTS: A total of 5.2% of hospitalizations were followed by a potentially avoidable readmission, 17% of them in a different hospital. The predictive value of the screen was 78%; 27% of screened readmissions were judged clearly avoidable. The correlation between the hospital rate of clearly avoidable readmission and all readmissions rate, potentially avoidable readmissions rate or the ratio of observed to expected readmissions were respectively 0.42, 0.56 and 0.66. Adjustment models using clinical information performed better. CONCLUSION: Adjusted rates of potentially avoidable readmissions are scientifically sound enough to warrant their inclusion in hospital quality surveillance.

Adolescent↗
PubMed2003

Social factors and increase in mortality in Russia in the 1990s: prospective cohort study.

OBJECTIVE: To determine the association between social factors and the increase in mortality in Russia in the 1990s. DESIGN: Prospective population cohort study. SETTING: Saint Petersburg, Russia. PARTICIPANTS: Two cohorts of men aged 40-59 years randomly selected from district voting list: 3907 screened in 1975-7 and 1467 in 1986-8. MAIN OUTCOME MEASURES: Education, various health related measures, alcohol intake. Mortality in subsequent 10 years. RESULTS: There was no recorded increase in mortality in men with university degrees. The relative risk in the second cohort compared with the first was 0.92 (95% confidence interval 0.67 to 1.24). For participants with only high school education it was significantly higher in the second cohort (1.32, 1.02 to 1.71). The most pronounced differences were found among participants with the lowest level of education, in which the relative risk was 1.75 (1.44 to 2.12). The same pattern held for coronary vascular disease and cancer mortality. CONCLUSION: In Russia men in the lower socioeconomic groups were most affected by the sharp increases in mortality in the 1990s.

Adult↗
PubMed1995

Xylitol chewing gums and caries rates: a 40-month cohort study.

Dental caries is a pandemic infectious disease which can affect the quality of life and consumes considerable health care resources. The chewing of xylitol, sorbitol, and even sugar gum has been suggested to reduce caries rates. No clinical study has simultaneously investigated the effectiveness of these gums when compared with a group receiving no chewing gum. A 40-month double-blind cohort study on the relationship between the use of chewing gum and dental caries was performed in 1989-1993 in Belize, Central America. One thousand two hundred and seventy-seven subjects (mean age, 10.2 years) were assigned to nine treatment groups: one control group (no supervised gum use), four xylitol groups (range of supervised xylitol consumption: 4.3 to 9.0 g/day), two xylitol-sorbitol groups (range of supervised consumption of total polyols: 8.0 to 9.7 g/day), one sorbitol group (supervised consumption: 9.0 g/day). The gum use during school hours was supervised. Four calibrated dentists performed the caries registrations by means of a modified WHO procedure. The primary endpoint was the development of an unequivocal caries lesion on a non-cavitated tooth surface. Compared with the no-gum group, sucrose gum usage resulted in a marginal increase in the caries rate (relative risk, 1.20; 95% confidence interval,0.96 to 1.49; p = 0.1128). Sorbitol gum significantly reduced caries rates (relative risk 0.74; 95% confidence interval, 0.6 to 0.92 ; p = 0.0074). The four xylitol gums were most effective in reducing caries rates, the most effective agent being a 100% xylitol pellet gum (relative risk, 0.27; 95% confidence interval, 0.20 to 0.36; p = 0.0001). This gum was superior to any other gum (p < 0.01). The xylitol-sorbitol mixtures were less effective than xylitol, but they reduced caries rates significantly compared with the no-gum group. DMFS analyses were consistent with these conclusions. The results suggest that systematic usage of polyol-based chewing gums reduces caries rates in young subjects, with xylitol gums being more effective than sorbitol gums.

Belize↗
PubMed1995

Incidence of alopecia areata in Olmsted County, Minnesota, 1975 through 1989.

OBJECTIVE: To assess the incidence and natural history of alopecia areata (AA) among unselected patients from a community. DESIGN: We conducted a retrospective population-based descriptive study of AA among residents of Olmsted County, Minnesota, for the period from 1975 through 1989. MATERIAL AND METHODS: After identifying 292 Olmsted County residents first diagnosed with AA during the 15-year study period, we reviewed their complete (inpatient and outpatient) medical records in the community and statistically analyzed the effects of gender and age-group. RESULTS: The overall incidence of AA was 20.2 per 100,000 person-years and did not change with time. Rates were similar in the two genders and over all ages, and lifetime risk was estimated at 1.7%. Eighty-seven percent of patients were examined by a dermatologist who diagnosed AA, and 29% of cases were confirmed by biopsy. Most patients had mild or moderate disease, but alopecia totalis or universalis developed at some point during the clinical course in 21 patients. CONCLUSION: This study of the incidence and natural history of AA in a community shows that this disorder is fairly common and can be seen at all ages. Although spontaneous resolution is expected in most patients, a small but significant proportion of cases (probably approximately 7%) may evolve into severe and chronic hair loss, which may be psychosocially devastating for affected persons.

Adolescent↗
PubMed1994

Chemical mutagenesis testing in Drosophila. X. Results of 70 coded chemicals tested for the National Toxicology Program.

Seventy chemicals were tested for the ability to induce sex-linked recessive lethal (SLRL) mutations in postmeiotic and meiotic germ cells of male Drosophila melanogaster. As in the previous studies in this series, adult feeding was chosen as the first route of administration. If the compound failed to induce mutations by this route, injection exposure was used. Two chemicals, n-butane and propylene, were gaseous and therefore tested only by inhalation. One chemical (dimethylcarbamoyl chloride) was tested only by injection. Those chemicals that were mutagenic in the SLRL assay were further tested for the ability to induce reciprocal translocations. Sixteen of the 70 chemicals tested were mutagenic in the SLRL assay: 3-chloro-2-methylpropene, 3-(chloromethyl)pyridine HCl, dimethylcarbamoyl chloride, HC blue 1,3-iodo-1,2-propanediol, malaoxon, N,N'-methylene-bis-acrylamide, 4,4'-methylenedianiline 2HCl, ziram, cis-dichlorodiaminoplatinum II, 1,2-dibromoethane, dibromomannitol, 1,2-epoxypropane, glycidol, myleran, and toluene diisocyanate. The last seven also induced reciprocal translocations. A comparison of the results from the SLRL assay with other assays for mutagens and carcinogens suggests that the SLRL assay is highly specific, but poorly sensitive, both for mutagens and potential carcinogens.

Animals↗
PubMed2000

Epidemic of coeliac disease in Swedish children.

Coeliac disease has emerged as a public health problem. The aim of the present study was to analyse trends in the occurrence of symptomatic coeliac disease in Swedish children from 1973 to 1997, and to explore any temporal relationship to changes in infant dietary patterns. We established a population-based prospective incidence register of coeliac disease in 1991, and, in addition, retrospective data from 1973 were collected. A total of 2151 cases fulfilled the diagnostic criteria. Furthermore. We collected national data on a yearly basis on duration of breastfeeding, intake of gluten-containing cereals and recommendations on when and how to introduce gluten into the diet of infants. From 1985 to 1987 the annual incidence rate in children below 2 y of age increased fourfold to 200-240 cases per 100000 person years, followed from 1995 by a sharp decline to the previous level of 50-60 cases per 100000 person years. This epidemic pattern is quite unique for a chronic disease of immunological pathogenesis, suggesting that prevention could be possible. The ecological observations made in this study are compatible with the epidemic being the result, at least in part, of a change in and an interplay among three factors within the area of infant feeding, i.e. amount of gluten given, age at introduction of gluten, and whether breastfeeding was ongoing or not when gluten was introduced. Other factor(s) may also have contributed, and the search for these should be intensified.

Adolescent↗
PubMed1988

Postmarketing surveillance for neurologic adverse events reported after hepatitis B vaccination. Experience of the first three years.

In 1982, the Centers for Disease Control, the Food and Drug Administration, and the manufacturer created a surveillance system to monitor spontaneous reports of adverse events occurring after inoculation with the new plasma-derived hepatitis B vaccine (Heptavax-B, Merck Sharp and Dohme, West Point, PA). In the three years between June 1, 1982 and May 31, 1985, an estimated 850,000 persons received the vaccine. During that period, a total of 41 reports were received for one of the following neurologic adverse events: convulsions (five cases), Bell's palsy (10 cases), Guillain-Barré syndrome (nine cases), lumbar radiculopathy (five cases), brachial plexus neuropathy (three cases), optic neuritis (five cases), and transverse myelitis (four cases). Half of these occurred after the first of three required vaccine doses. There were no deaths. Calculation of the relative risks of these illnesses after hepatitis B vaccination was highly dependent on diagnostic classification of the cases, estimates of the size of the vaccinated population, background incidence of the diseases, and the length and distribution of the hypothetical at-risk interval used in the analysis. Other factors important in judging the results of the study could not be measured, including underreporting. In some analyses, Guillain-Barré syndrome was reported significantly more often than expected (p less than 0.05, Poisson probability distribution). However, no conclusive epidemiologic association could be made between any neurologic adverse event and the vaccine. Even if such an association did exist, the preventive benefits of the vaccine in persons at high risk for hepatitis B would unequivocally outweigh the risk of any neurologic adverse event.

Evaluation Studies as Topic↗
PubMed2005

Resurgence of pertussis in Europe.

BACKGROUND: A resurgence of pertussis has been observed in Canada, the United States and Australia since the 1980s, but inconsistent data are currently available for Europe. The objective of this paper is to describe the epidemiology of pertussis in Western European countries to discuss future vaccination strategies. METHODS: The European Community funded a network for the epidemiologic surveillance of measles and pertussis in 1998. Sixteen European countries provided national surveillance data for pertussis for the period 1998-2002 in a standard format. Data were pooled and analyzed to describe incidence rates by age group, seasonality, proportion of hospitalized patients and deaths among notified cases. RESULTS: Children younger than 1 year had the highest incidence during the entire period. Rates in the older than 14 years age group increased by 115% during the study period. Northern countries showed the highest incidence figures in all age groups. Among children younger than 1 year, 70% were admitted into hospital. Children younger than 6 months of age and those not vaccinated were most likely to be hospitalized. Thirty-two deaths were reported, 87% of which were in children younger than 6 months of age. CONCLUSIONS: Pertussis is far from being controlled in Europe. Whereas the incidence in children younger than 1 year was high but remained stable, rates in adults doubled in 5 years.

Adolescent↗
PubMed2005

Diffusion-annihilation processes in complex networks.

We present a detailed analytical study of the A+A --> 0 diffusion-annihilation process in complex networks. By means of microscopic arguments, we derive a set of rate equations for the density of A particles in vertices of a given degree, valid for any generic degree distribution, and which we solve for uncorrelated networks. For homogeneous networks (with bounded fluctuations), we recover the standard mean-field solution, i.e., a particle density decreasing as the inverse of time. For heterogeneous (scale-free networks) in the infinite network size limit, we obtain instead a density decreasing as a power law, with an exponent depending on the degree distribution. We also analyze the role of finite size effects, showing that any finite scale-free network leads to the mean-field behavior, with a prefactor depending on the network size. We check our analytical predictions with extensive numerical simulations on homogeneous networks with Poisson degree distribution and scale-free networks with different degree exponents.

Journal Article↗
PubMed2006

Fatal injuries while under the influence of psychoactive drugs: a cross-sectional exploratory study in England.

BACKGROUND: Studies of drug-related mortality rarely describe fatal injuries due to psychoactive drug intoxication (FIUI). The main aim of this study was to determine the nature, extent and pattern of FIUI. METHODS: This observational study covered the period January 1999 to December 2001. Data were provided by members of a study panel of coroners in England using a standard protocol. Sources of data for this study included autopsy protocols, death certificates, hospital records, police reports, toxicology reports and inquest transcripts. Inclusion criteria for this were (i) the mention of one or more psychoactive substances as contributing to fatality; and (ii) the presence of a Controlled Drug at post mortem. RESULTS: A total of 3,803 drug-related deaths of persons aged 16-64 years were reported by the study panel during the three-year period. The study panel accounted for 86% of drug-related deaths in England in this period. There were 147 FIUI cases (119 males, 28 females), giving a proportionate mortality ratio of approximately 4%. The majority of FIUI cases (84%) were aged 16-44 years, with a median age at death of 33 years (Quartile deviation = 7). Fifty-six percent of FIUI occurred in urban areas of England. The population of the study jurisdictions aged 16-64 years contributed 49,545,766 person-years (py) to the study, giving an annual crude rate of 3/1,000,000 person-years (py). Rates for male and females were 4.9 and 1.1/1,000,000 py respectively, giving a male/female rate ratio of 4.5 (95%CI = 2.9-6.8). The rates of intentional and unintentional FIUI were 2 and 1/1,000,000 py respectively. The leading mechanism for intentional FIUI was suffocation while the predominant mechanisms in unintentional FIUI were road traffic accidents and falls. There is a significant difference in the pattern of drug-specific risk between FIUI and fatal poisoning. Risks of intentional FIUI are elevated among Black and Minority Ethnic groups. CONCLUSION: There are differences in the nature, extent and pattern of intentional and unintentional FIUI that should necessitate targeted prevention strategies. Also, there is an opportunity for cross-discipline collaboration between injury prevention specialists and substance abuse/mental health specialists.

Accidents↗