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Aims: To describe and compare the adherence to different direct oral anticoagulants (DOACs) in eight European databases representing six countries. Methods: Longitudinal drug utilization study of new users (≥18 years) of DOACs (dabigatran, rivaroxaban, apixaban) with a diagnosis of non-valvular atrial fibrillation (2008-2015). Adherence was examined by estimating persistence, switching, and discontinuation rates at 12 months. Primary non-adherence was estimated in BIFAP and SIDIAP databases. Results: The highest persistence rate was seen for apixaban in the CPRD database (81%) and the lowest for dabigatran in the Mondriaan database (22%). The switching rate for all DOACs ranged from 2.4 to 13.1% (Mondriaan and EGB databases, respectively). Dabigatran had the highest switching rate from 5.0 to 20.0% (Mondriaan and EGB databases, respectively). The discontinuation rate for all DOACs ranged from 16.0 to 63.9% (CPRD and Bavarian CD databases, respectively). Dabigatran had the highest rate of discontinuers, except in the Bavarian CD and AOK NORDWEST databases, ranging from 23.2 to 64.6% (CPRD and Mondriaan databases, respectively). Combined primary non-adherence for examined DOACs was 11.1% in BIFAP and 14.0% in SIDIAP. There were differences in population coverage and in the type of drug data source among the databases. Conclusion: Despite the differences in the characteristics of the databases and in demographic and baseline characteristics of the included population that could explain some of the observed discrepancies, we can observe a similar pattern throughout the databases. Apixaban was the DOAC with the highest persistence. Dabigatran had the highest proportion of discontinuers and switchers at 12 months in most databases (EMA/2015/27/PH).
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The loss of bone and muscle mass increases the risk of osteoporotic fractures. Dual energy X-ray absorptiometry (DXA) loses sensitivity in older age. The purpose of this study was to evaluate bone and muscle measurements of peripheral quantitative computed tomography (pQCT) in a geriatric cohort with osteoporosis. Bone mineral density and muscle area of 168 patients aged 65 years and older (76.3 ± 6.5) were measured with pQCT at distal forearm additionally to an osteoporosis assessment consisting of anamnesis, blood test and DXA of lumbar spine and hip. Prior fractures were categorized in minor and major osteoporotic fractures. Logistic regression was used to show the association of bone mineral density and muscle area with major fractures. 54.8% of the participants had at least one major fracture. Bone mineral density measured with pQCT and muscle area were significantly associated with these fractures (total and trabecular bone mineral density OR 2.243 and 2.195, p < 0.01; muscle area OR 2.378, p < 0.05), whereas DXA bone mineral density showed no significant association. These associations remained after adjustment for age, sex, BMI, physical activity and other factors. In all models for patients >75 years only muscle area was significantly associated (OR 5.354, p < 0.05) with major fractures. Measurement of bone mineral density and muscle area with pQCT seems to have advantage over DXA in fracture association in geriatric patients. Measuring muscle area also adds useful information to estimate the presence of osteosarcopenia.
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Músculo Esquelético/diagnóstico por imagem , Rádio (Anatomia)/diagnóstico por imagem , Absorciometria de Fóton , Idoso , Idoso de 80 Anos ou mais , Densidade Óssea , Osso Esponjoso/anatomia & histologia , Osso Esponjoso/diagnóstico por imagem , Feminino , Humanos , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/patologia , Masculino , Músculo Esquelético/patologia , Osteoporose/diagnóstico por imagem , Osteoporose/patologia , Fraturas por Osteoporose/diagnóstico por imagem , Fraturas por Osteoporose/patologia , Ossos Pélvicos/diagnóstico por imagem , Ossos Pélvicos/patologia , Rádio (Anatomia)/patologia , Tomografia Computadorizada por Raios X/métodosRESUMO
Presently, routine screening misses many cases of prediabetes and early type 2 diabetes (T2D). Therefore, better biomarkers are needed for a simple and early detection of abnormalities of glucose metabolism and prediction of future T2D. Possible candidates for this include plasma or serum amino acids because glucose and amino acid metabolism are closely connected. This review presents the available evidence of this connectivity and discusses its clinical implications. First, we examine the underlying physiological, pre-analytical, and analytical issues. Then, we summarize results of human studies that evaluate amino acid levels as markers for insulin resistance, prediabetes, and future incident T2D. Finally, we illustrate the interconnection of amino acid levels and metabolic syndrome with our own data from a deeply phenotyped human cohort. We also discuss how amino acids may contribute to the pathophysiology of T2D. We conclude that elevated branched-chain amino acids and reduced glycine are currently the most robust and consistent amino acid markers for prediabetes, insulin resistance, and future T2D. Yet, we are cautious regarding the clinical potential even of these parameters because their discriminatory power is insufficient and their levels depend not only on glycemia, but also on other components of the metabolic syndrome. The identification of more precise intermediates of amino acid metabolism or combinations with other biomarkers will, therefore, be necessary to obtain in order to develop laboratory tests that can improve T2D screening.
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Aminoácidos , Diabetes Mellitus Tipo 2 , Resistência à Insulina/fisiologia , Metaboloma/fisiologia , Estado Pré-Diabético , Aminoácidos/sangue , Aminoácidos/metabolismo , Animais , Biomarcadores/sangue , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/metabolismo , Humanos , Metabolômica , Estado Pré-Diabético/sangue , Estado Pré-Diabético/diagnóstico , Estado Pré-Diabético/metabolismoRESUMO
BACKGROUND: Studies evaluating the impact of age and potentially inappropriate medication (PIM) on avoidable adverse drug reactions (ADRs) are scarce. METHODS: In this prospective, multi-center, long-term (8.5 years) observational study, we analysed ADRs leading to hospitalization in departments of internal medicine. ADRs causality and preventability were assessed using standardised algorithms. PIM was defined based on the PRISCUS-list. Multivariate analyses and estimation of ADR incidence rates were conducted. RESULTS: Of all 6,427 ADR patients, a preventable ADR was present in 1,253 (19.5%) patients (elderly patients ≥70 years: 828). Risk factors for preventable ADRs in elderly patients were multimorbidity, two to four ADR-causative drugs, and intake of particular compounds (e.g. spironolactone) but not sex, PIM usage, or the total number of drugs. Regarding particular compounds associated with preventable ADRs, highest incidence rates for preventable ADRs were found for patients aged ≥70 years for spironolactone (3.3 per 1,000 exposed persons (95% CI: 1.4-6.6)) and intermediate-acting insulin (3.3 per 1,000 exposed persons (95% CI: 1.6-6.1)). CONCLUSION: Avoiding PIM usage seems to be of limited value in increasing safety in elderly patients whereas our results underline the importance of an individualized medication review of the most commonly implicated drugs in preventable ADRs (supported by BfArM FoNr: V-11337/68605/2008-2010).
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Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/epidemiologia , Hospitalização/estatística & dados numéricos , Prescrição Inadequada/estatística & dados numéricos , Lista de Medicamentos Potencialmente Inapropriados , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/prevenção & controle , Feminino , Humanos , Incidência , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Estudos Prospectivos , Fatores de RiscoRESUMO
BACKGROUND: Familial partial lipodystrophies are rare monogenic disorders that are often associated with diabetes. In such cases, it can be difficult to achieve glycaemic control. CASE REPORT: We report a 34-year old woman with familial partial lipodystrophy type 2 (Dunnigan) and diabetes; her hyperglycaemia persisted despite metformin treatment. A combined intravenous glucose tolerance-euglycaemic clamp test showed severe insulin resistance, as expected, but also showed strongly diminished first-phase insulin secretion. After the latter finding, we added the glucagon-like peptide-1 receptor agonist liraglutide to the patient's treatment regimen, which rapidly normalized plasma glucose levels. HbA1c values <42 mmol/mol (6.0%) have now been maintained for over 4 years. CONCLUSION: This case suggests that a glucagon-like peptide-1 receptor agonist may be a useful component of glucose-lowering therapy in individuals with familial partial lipodystrophy and diabetes mellitus.
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Receptor do Peptídeo Semelhante ao Glucagon 1/agonistas , Insulina/metabolismo , Lipodistrofia Parcial Familiar/tratamento farmacológico , Liraglutida/uso terapêutico , Adulto , Feminino , Seguimentos , Humanos , Resistência à Insulina , Secreção de Insulina , Lipodistrofia Parcial Familiar/metabolismo , Fatores de Tempo , Resultado do TratamentoRESUMO
AIMS/HYPOTHESIS: Low physical fitness (PF) is a risk factor for type 2 diabetes mellitus (T2D). Women with a history of gestational diabetes (GDM) are at risk for T2D at a young age, but the role of PF in this population is not clear. PF has also been found to correlate inversely with plasma leptin in previous studies. Here, we examine whether women who had GDM have lower PF than women after a normoglycemic pregnancy and, second, whether PF is associated with plasma leptin, independently of body fat mass. METHODS: Cross-sectional analysis of 236 participants in the PPSDiab Study (cohort study of women 3-16 months after delivery, 152 after gestational diabetes (pGDM), 84 after normoglycemic pregnancy (control subjects); consecutively recruited 2011-16); medical history, physical examination with bioelectrical impedance analysis (BIA), whole body magnetic resonance imaging (MRI) (n = 154), 5-point oral glucose tolerance test, cardiopulmonary exercise testing, clinical chemistry including fasting plasma leptin; statistical analysis with Mann-Whitney U and t -test, Spearman correlation coefficient, multiple linear regression. RESULTS: Women pGDM had lower maximally achieved oxygen uptake (VO2peak/kg: 25.7(21.3-29.9) vs. 30.0(26.6-34.1)ml/min/kg; total VO2peak: 1733(1552-2005) vs. 1970(1767-2238)ml/min; p<0.0001 for both), and maximum workload (122.5(105.5-136.5) vs. 141.0(128.5-159.5)W; p<0.0001). Fasting plasma leptin correlated inversely with PF (VO2peak/kg ρ = -0.72 p<0.0001; VO2peak ρ = -0.16 p = 0.015; max. load ρ = -0.35 p<0.0001). These associations remained significant with adjustment for body mass index, or for body fat mass (BIA and MRI). CONCLUSIONS/INTERPRETATION: Women with a recent history of GDM were less fit than control subjects. Low PF may therefore contribute to the risk for T2D after GDM. This should be tested in intervention studies. Low PF also associated with increased leptin levels-independently of body fat. PF may therefore influence leptin levels and signaling. This hypothesis requires further investigation.
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Diabetes Gestacional/sangue , Diabetes Gestacional/fisiopatologia , Leptina/sangue , Aptidão Física/fisiologia , Adulto , Glicemia/metabolismo , Índice de Massa Corporal , Estudos Transversais , Diabetes Mellitus Tipo 2/sangue , Feminino , Teste de Tolerância a Glucose , Humanos , Modelos Lineares , Consumo de Oxigênio , Gravidez , Estudos Prospectivos , Fatores de RiscoRESUMO
PURPOSE: Results from observational studies on inhaled long-acting beta-2-agonists (LABA) and acute myocardial infarction (AMI) risk are conflicting, presumably due to variation in methodology. We aimed to evaluate the impact of applying a common study protocol on consistency of results in three databases. METHODS: In the primary analysis, we included patients from two GP databases (Dutch-Mondriaan, UK-CPRD GOLD) with a diagnosis of asthma and/or COPD and at least one inhaled LABA or a "non-LABA inhaled bronchodilator medication" (short-acting beta-2-agonist or short-/long-acting muscarinic antagonist) prescription between 2002 and 2009. A claims database (USA-Clinformatics) was used for replication. LABA use was divided into current, recent (first 91 days following the end of a treatment episode), and past use (after more than 91 days following the end of a treatment episode). Adjusted hazard ratios (AMI-aHR) and 95 % confidence intervals (95 % CI) were estimated using time-dependent multivariable Cox regression models stratified by recorded diagnoses (asthma, COPD, or both asthma and COPD). RESULTS: For asthma or COPD patients, no statistically significant AMI-aHRs (age- and sex-adjusted) were found in the primary analysis. For patients with both diagnoses, a decreased AMI-aHR was found for current vs. recent LABA use in the CPRD GOLD (0.78; 95 % CI 0.68-0.90) and in Mondriaan (0.55; 95 % CI 0.28-1.08), too. The replication study yielded similar results. Adjusting for concomitant medication use and comorbidities, in addition to age and sex, had little impact on the results. CONCLUSIONS: By using a common protocol, we observed similar results in the primary analysis performed in two GP databases and in the replication study in a claims database. Regarding differences between databases, a common protocol facilitates interpreting results due to minimized methodological variations. However, results of multinational comparative observational studies might be affected by bias not fully addressed by a common protocol.
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Agonistas de Receptores Adrenérgicos beta 2/efeitos adversos , Bases de Dados Factuais , Infarto do Miocárdio/induzido quimicamente , Administração por Inalação , Agonistas de Receptores Adrenérgicos beta 2/uso terapêutico , Asma/tratamento farmacológico , Europa (Continente) , Humanos , Atenção Primária à Saúde , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico , Projetos de Pesquisa , Estados UnidosRESUMO
We analyzed the association of sleep quality and glucose metabolism in women after gestational diabetes (pGDM) and in women after normoglycemic pregnancy (controls). Data during pregnancy and a visit within the first 15 months after delivery were collected from 61 pGDM and 30 controls in a prospective cohort study. This included a medical history, physical examination, questionnaires (Pittsburgh Sleep Quality Index (PSQI), and Perceived Stress Scale (PSS)), and 5-point oral glucose tolerance test with insulin measurements to determine indices of insulin sensitivity and insulin secretion. We used Spearman correlation coefficients and multivariate regression models for analysis.9.3 ± 3.2 months after delivery, pGDM had significantly higher fasting and 2 h glucose levels and lower insulin sensitivity than controls. There was no significant difference in age, BMI and sleep quality as assessed with the PSQI between the two groups. The PSQI score correlated with the ogtt-2 h plasma glucose in pGDM (δ = 0.41; p = 0.0012), but not in controls. This association was confirmed with a multivariate linear regression model with adjustment for age, BMI and months post-delivery. Perceived stress was an independent risk factor (OR 1.12; 95% CI 1.02-1.23) for impaired sleep. Our findings suggest that post-delivery sleep quality significantly influences glucose tolerance in women after GDM and that impaired sleep is associated with increased stress perception. Measures to improve of sleep quality and reduce perceived stress should therefore be tested as additional strategies to prevent progression to type 2 diabetes after GDM.
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Glicemia/metabolismo , Complicações do Diabetes/complicações , Diabetes Gestacional/fisiopatologia , Transtornos do Sono-Vigília/etiologia , Adulto , Feminino , Teste de Tolerância a Glucose , Humanos , Gravidez , Fatores de Risco , Inquéritos e QuestionáriosRESUMO
BACKGROUND: For patients with asthma, COPD, or asthma-COPD overlap syndrome (ACOS), inter-country comparisons of seasonal changes in drug prescriptions are scarce or missing. Hence, we aimed to compare seasonal changes in prescription rates of long-acting beta-2-agonist (LABA) in four European countries. METHODS: A common study protocol was applied to six health care databases (Germany, Spain, the Netherlands (2), and the UK (2)) to calculate age- and sex-standardized point prevalence rates (PPRs) of LABA-containing prescriptions by the 1st of March, June, September, and December of each year during the study period 2002-2009. Seasonal variation of PPRs was quantified using seasonal indexes (SIs; based on the ratio-to-moving-average-method) and SIs averaged over the study period (aSI) stratified by sex, age, and indication (asthma, COPD, or ACOS). RESULTS: There was a moderate seasonal change in LABA-containing prescriptions which was more pronounced in asthma or COPD patients compared to ACOS patients. For asthma and ACOS patients, highest seasonal variation was found for patients living in Spain (aSI: 87.3-110.7, aSI: 93.2-103.1) whereas for COPD highest seasonal variation was revealed for the NPCRD database (the Netherlands) (aSI: 92.2-105.6). Regarding age and sex, highest seasonal variation was found in Spanish boys under 10 years of age having a diagnosis of asthma. CONCLUSIONS: By applying a common analysis in six databases, we could observe moderate overall seasonal changes in LABA-containing prescription rates in patients with asthma, COPD, or ACOS.
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Agonistas de Receptores Adrenérgicos beta 2/administração & dosagem , Asma/tratamento farmacológico , Prescrições de Medicamentos/estatística & dados numéricos , Padrões de Prática Médica , Administração por Inalação , Adolescente , Adulto , Asma/epidemiologia , Criança , Preparações de Ação Retardada/administração & dosagem , Europa (Continente) , Feminino , Humanos , Masculino , Estudos Retrospectivos , Estações do Ano , Índice de Gravidade de Doença , Adulto JovemRESUMO
BACKGROUND AND PURPOSE: Collateral blood flow is an important prognostic marker in the acute stroke situation but approaches for assessment vary widely. Our aim was to compare strategies of collateral blood flow assessment in dynamic and conventional CTA in their ability to predict the follow-up infarction volume. MATERIALS AND METHODS: We retrospectively included all patients with an M1 occlusion from an existing cohort of 1912 consecutive patients who underwent initial multimodal stroke CT and follow-up MR imaging or nonenhanced CT. Collateralization was assessed in both conventional CT angiography and dynamic CT angiography by using 3 different collateral grading scores and segmentation of the volume of hypoattenuation. Arterial, arteriovenous, and venous phases were reconstructed for dynamic CT angiography, and all collateral scores and the volume of hypoattenuation were individually assessed for all phases. Different grading systems were compared by using the Bayesian information criterion calculated for multivariate regression analyses (Bayesian information criterion difference = 2-6, "positive"; Bayesian information criterion difference = 6-10, "strong"; Bayesian information criterion difference = >10, "very strong"). RESULTS: One hundred thirty-six patients (mean age, 70.4 years; male sex, 41.2%) were included. In the multivariate analysis, models containing the volume of hypoattenuation showed a significantly better model fit than models containing any of the 3 collateral grading scores in conventional CT angiography (Bayesian information criterion difference = >10) and dynamic CT angiography (Bayesian information criterion difference = >10). All grading systems showed the best model fit in the arteriovenous phase. For the volume of hypoattenuation, model fit was significantly higher for models containing the volume of hypoattenuation as assessed in the arteriovenous phase of dynamic CT angiography compared with the venous phase (Bayesian information criterion difference = 6.2) and the arterial phase of dynamic CT angiography (Bayesian information criterion difference = >10) and in comparison with conventional CT angiography (Bayesian information criterion difference = >10). CONCLUSIONS: The use of dynamic CT angiography within the arteriovenous phase by using quantification of the volume of hypoattenuation is the superior technique for assessment of collateralization among the tested approaches.
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Isquemia Encefálica/fisiopatologia , Infarto Cerebral/fisiopatologia , Circulação Cerebrovascular/fisiologia , Circulação Colateral/fisiologia , Acidente Vascular Cerebral/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Angiografia/métodos , Teorema de Bayes , Feminino , Seguimentos , Humanos , Processamento de Imagem Assistida por Computador , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Acidente Vascular Cerebral/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodosRESUMO
PURPOSE: Drug utilization studies have applied different methods to various data types to describe medication use, which hampers comparisons across populations. The aim of this study was to describe the time trends in antidepressant prescribing in the last decade and the variation in the prevalence, calculated in a uniform manner, in seven European electronic healthcare databases. METHODS: Annual prevalence per 10,000 person-years (PYs) was calculated for 2001-2009 in databases from Spain, Germany, Denmark, the United Kingdom (UK), and the Netherlands. Prevalence data were stratified according to age, sex, antidepressant type (selective serotonin re-uptake inhibitors [SSRIs] or tricyclic antidepressants [TCAs]) and major indications. RESULTS: The age- and sex-standardized prevalence was lowest in the two Dutch (391 and 429 users per 10,000 PYs) and highest in the two UK (913 and 936 users per 10,000 PYs) populations in 2008. The prevalence in the Danish, German, and Spanish populations was 637, 618, and 644 users per 10,000 PY respectively. Antidepressants were prescribed most often in 20- to 60-year-olds in the two UK populations compared with the others. SSRIs were prescribed more often than TCAs in all except the German population. In the majority of countries we observed an increasing trend of antidepressant prescribing over time. Two different methods identifying recorded indications yielded different ranges of proportions of patients recorded with the specific indication (15-57% and 39-69% for depression respectively). CONCLUSION: Despite applying uniform methods, variations in the prevalence of antidepressant prescribing were obvious in the different populations. Database characteristics and clinical factors may both explain these variations.
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Antidepressivos/uso terapêutico , Padrões de Prática Médica/tendências , Adulto , Idoso , Idoso de 80 Anos ou mais , Prescrições de Medicamentos , Revisão de Uso de Medicamentos , Europa (Continente) , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de TempoRESUMO
Hip fractures represent a major public health challenge worldwide. Multinational studies using a common methodology are scarce. We aimed to estimate the incidence rates (IRs) and trends of hip/femur fractures over the period 2003-2009 in five European countries. The study was performed using seven electronic health-care records databases (DBs) from Denmark, The Netherlands, Germany, Spain, and the United Kingdom, based on the same protocol. Yearly IRs of hip/femur fractures were calculated for the general population and for those aged ≥50 years. Trends over time were evaluated using linear regression analysis for both crude and standardized IRs. Sex- and age-standardized IRs for the UK, Netherlands, and Spanish DBs varied from 9 to 11 per 10,000 person-years for the general population and from 22 to 26 for those ≥50 years old; the German DB showed slightly higher IRs (about 13 and 30, respectively), whereas the Danish DB yielded IRs twofold higher (19 and 52, respectively). IRs increased exponentially with age in both sexes. The ratio of females to males was ≥2 for patients aged ≥70-79 years in most DBs. Statistically significant trends over time were only shown for the UK DB (CPRD) (+0.7% per year, P < 0.01) and the Danish DB (-1.4% per year, P < 0.01). IRs of hip/femur fractures varied greatly across European countries. With the exception of Denmark, no decreasing trend was observed over the study period.
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Fraturas do Colo Femoral/epidemiologia , Fraturas do Quadril/epidemiologia , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Bases de Dados Factuais , Dinamarca/epidemiologia , Registros Eletrônicos de Saúde , Feminino , Alemanha/epidemiologia , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Países Baixos/epidemiologia , Distribuição por Sexo , Espanha/epidemiologia , Reino Unido/epidemiologiaRESUMO
BACKGROUND: It has been shown that varicella zoster virus (VZV) and herpes simplex virus (HSV) can co-localize to the same sensory ganglion. However, only a few case reports on VZV/HSV co-infections exist. Objective To identify and characterize patients with concurrent VZV and HSV infection at the same body site. SUBJECTS/METHODS: In 1718 patients, the presence of VZV and HSV in suspicious skin lesions was investigated by polymerase chain reaction analysis. Clinical characteristics of co-infected patients were compared with matched control patients infected with either VZV or HSV. The data are discussed in the context of an extensive review of the literature. RESULTS: Twenty (1.2%) of 1718 patients were infected with both VZV and HSV at the same body site. The mean age was 54 years (range, 2-83). The clinical diagnosis was zoster in 65%, herpes simplex in 20%, varicella in 10% and erythema multiforme in 5% of cases. The trigeminus region was affected in 60% and the trunk in 25%. Involvement of the head was most commonly associated with a severe course of disease and with older age. CONCLUSION: Simultaneous VZV/HSV infection is rare but can occur in immunocompetent patients, which is often overlooked. The majority of cases is localized to the trigeminus region and affects elderly people.
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Varicela/complicações , Herpes Zoster/complicações , Imunocompetência , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Sequência de Bases , Varicela/diagnóstico , Criança , Pré-Escolar , Primers do DNA , Diagnóstico Diferencial , Feminino , Herpes Zoster/diagnóstico , Herpesvirus Humano 1/genética , Herpesvirus Humano 1/isolamento & purificação , Herpesvirus Humano 3/genética , Herpesvirus Humano 3/isolamento & purificação , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Estudos RetrospectivosRESUMO
PURPOSE: We developed a method for measuring ophthalmic surfaces based on a Twyman-Green interferometer. METHODS: To demonstrate the accuracy, we measured the anterior surface of four used hard contact lenses and evaluated the interference pattern with phase shift technique. The obtained interferograms were evaluated by an image processing system. RESULTS: The interferometric resolution of the measurement is up to lambda/20 (30 nm) which refers to a dioptric resolution of about delta D = 10(-3) m(-1) for typical anterior radii of curvature. The dioptric maps were calculated from the height distribution. As we used a focus tracking distance measurement setup with an accuracy of 10 microns we could determine the absolute value of the dioptric number to be delta D approximately 0.04 m-1. To demonstrate the accuracy we tested contact lenses which were specified to have a spherical anterior surface. Obviously, the topography of contact lenses changes when worn. We measured astigmatic deviations up to 0.6 D in the central zone of the lenses. We briefly discuss the possibilities of this method concerning a topographer for measuring the fine corneal surface structure. CONCLUSIONS: The presented Twyman-Green interferometer with distance measurement and image processing system is a very accurate method for measuring the topographic properties of ophthalmic surfaces. The method may also be useful for studying the distribution of the tear layer on the contact lens, or the corneal topography.