L'analyse de survie concerne la modélisation des délais de réalisation d'un unique événement. Dans de nombreuses situations cependant, les individus sont soumis à plusieurs causes d'événement exclusives, définissant un cadre dit de risques concurrents ou compétitifs. <br />Ce travail de thèse a porté sur l'étude de modèles de régression dans ce cadre. Deux approches ont été envisagéés, l'une basée sur la fonction de risque instantané cause-spécifique et l'autre sur la <br />fonction de risque instantané associée à la fonction d'incidence cumulée (ou fonction de risque de sous-répartition). Dans les deux cas, nous avons considéré une formulation à risques proportionnels, c'est à dire un modèle de Cox dans le premier cas, et un modèle de Fine & Gray dans le second cas. <br />Dans un premier temps, l'implication d'un choix de modélisation a été étudiée dans le cadre de la planification d'un essai clinique ou d'une étude pronostique. Nous avons alors developpé<br />une formule de calcul du nombre de sujets nécessaire pour le modèle de Fine & Gray. <br />Puis, les conséquences d'un modèle mal spécifié pour la fonction de risque de sous répartition ont été evaluées, en étudiant l'influence sur l'estimation du paramètre de régression dans le modèle de Fine & Gray quand le vrai modèle est un modèle à risques proportionnels pour la fonction de risque cause- <br />spécifique. Nous avons ensuite étudié les implications de l'inclusion de covariables dépendantes du <br />temps dans le modèle de Fine & Gray. <br />Enfin, nous avons présenté une synthèse didactique sur la <br />stratégie d'utilisation des approches présentées dans ce travail de thèse.

Human papillomavirus (HPV) is the most common sexually transmitted infection in the United States, but few studies have examined the progression from HPV infection to disease in men. Genital condyloma are the most common clinical manifestation of HPV infection. Though not associated with mortality, condyloma are a source of emotional distress, and treatment is often painful with a high recurrence rate. The aims of this study were to examine the distribution of HPV types present on the surface of condyloma, estimate the incidence of condyloma overall and after type-specific HPV infections, assess the sociodemographic and sexual behavior factors independently associated with incident condyloma, and examine the concordance between HPV types detected on the surface and in the tissue of condyloma. Participants included 2,487 men from the United States, Brazil, and Mexico who were enrolled in the prospective HPV in Men (HIM) Study and followed every six months for up to four years. At each study visit men completed a computer-assisted-self-administered risk factor questionnaire and samples of healthy penile skin were obtained to test for HPV DNA. A trained clinician examined men for the presence of condyloma and swabbed the surface of lesions to test for HPV DNA. Men were followed for a median of 17.9 months and 112 incident condyloma were identified. Thirty-four external genital lesions were also biopsied to test for HPV within the lesion tissue. PCR was used to test for HPV DNA and Linear Array was used to genotype 13 oncogenic and 24 non-oncogenic HPV types in samples obtained from swabbing the lesion surface. The LiPa assay was used to genotype 20 HPV types in biopsy samples. The Kaplan-Meier method was used to estimate incidence and Cox proportional hazards models were used to examine factors independently associated with incident condyloma. Using biopsy samples as the gold standard, sensitivity and specificity were calculated to examine concordance between HPV types detected on the surface and within the tissue of condyloma. Condyloma incidence was 2.35 per 1,000 person-years. HPV 6 (43.8%), 11 (10.7%), and 16 (9.8%) were the most common types detected on condyloma. The probability of developing condyloma within 24-months of an incident HPV 6/11 infection was 14.6% (95% confidence interval (CI): 7.5-21.1). The median time to condyloma development was 17.1 months (95% CI: 12.4-19.3), with the shortest time to detection observed among men with incident HPV infections with types 6/11 only (6.2 months; 95% CI: 5.6-24.2). Factors associated with condyloma were incident HPV 6/11 infection (hazard ratio (HR) = 12.42; 95% CI: 3.78-40.77), younger age (HR = 0.43; 95% CI: 0.26-0.77; 45-70 vs. 18-30 years), high lifetime number of female partners (HR = 5.69; 95% CI: 1.80-17.97); 21 or greater vs. 0), and sexual behaviors in the previous three months including infrequent condom use (HR = 2.44; 95% CI: 1.16-5.14;

The current thesis is structured in four parts. Vector smoothing methods are used to study environmental data, in particular records of extreme precipitation, the models utilized belong to the vector generalized additive class. In the statistical analysis of observational studies the identification and adjustment for prognostic factors is an important component of the analysis; employing flexible statistical methods to identify and characterize the effect of potential prognostic factors in a clinical trial, namely "generalized additive models", presents an alternative to the traditional linear statistical model. The classes of models for which the methodology gives generalized additive extensions include grouped survival data from the Surveillance, Epidemiology, and End Results tumors of the brain and the central nervous system database; we are employing piecewise linear functions of the covariates to characterize the survival experienced by the population. Finally, both descriptive and analytical methods are utilized to study incidence rates and tumor sizes associated with the disease.

Streptococcus pneumoniae is a major bacterial pathogen which causes pneumoniae, meningitis, otitis media, and bacteremia. Currently there are two vaccines available, Pneumococcal Polysaccharide Vaccine (PPV) for adults and the Pneumococcal Conjugate Vaccine (PCV) for children. The PCV vaccine was developed in 2000 specifically for children and infants due to the ineffectiveness of the PPV vaccine in children. This is a cross sectional study of invasive S. pneumoniae in Florida during 2003. This study is designed to determine the population characteristics, clinically relevant antibiotic resistance patterns and specific risk factors for development of antibiotic resistance of invasive S. pneumoniae. Participants for the study of antimicrobial resistance will be selected if they are positive for invasive S. pneumoniae, and have been reported to the Florida Department of Health, Bureau of Epidemiology with a laboratory specimen collection date in 2003. A total of 1056 cases were reported. The incidence of invasive S. pneumoniae was calculated. Logistic regression was used to find an association between each risk factor and invasive S. pneumoniae. 95% Confidence Intervals were calculated to determine statistical significance. The incidence of invasive pneumococcal disease was calculated to be 6.61 per 100,000 persons (95% CI 6.21 -- 7.01). The incidence of drug resistant S. pneumoniae was calculated to be 3.3 per 100,000 persons (95% CI 3.03 -- 3.59).The incidence of penicillin resistant S. pneumoniae (PRSP) was estimated to be 2.6 per 100,000 persons (95% CI 2.37 -- 2.87). Fifty percent of the cases qualified as Drug Resistant S. pneumoniae (DRSP), being non-susceptible to one or more antibiotics as defined by the National Committee for Clinical Laboratory Standards (NCCLS). Age, race, gender, county and month of occurrence were evaluated as risk factors for DRSP. Only month of occurrence was determined to be a risk factor. Compared to current studies and previous results for Florida, it appears that Florida has a decreasing incidence of antibiotic resistant Streptococcus pneumoniae. I believe that this is due to the use of the PCV vaccine.

Central to the goals of public health are obtaining and interpreting timely and relevant information for the benefit of humanity. In this dissertation, we propose methods to monitor and assess the spread HIV in a more rapid manner, as well as to improve decisions regarding patient treatment options. In Chapter 1, we propose a method, extending the previously proposed dual-testing algorithm and augmented cross-sectional design, for estimating the HIV incidence rate in a particular community. Compared to existing methods, our proposed estimator allows for shorter follow-up time and does not require estimation of the mean window period, a crucial, but often unknown, parameter. The estimator performs well in a wide range of simulation settings. We discuss when this estimator would be expected to perform well and offer design considerations for the implementation of such a study. Chapters 2 and 3 are concerned with obtaining a more complete understanding of the impact of treatment in randomized clinical trials in which multiple patient outcomes are recorded. Chapter 2 provides an illustration of methods that may be used to address concerns of both risk-benefit analysis and personalized medicine simultaneously, with a goal of successfully identifying patients who will be ideal candidates for future treatment. Riskbenefit analysis is intended to address the multivariate nature of patient outcomes, while “personalized medicine” is concerned with patient heterogeneity, both of which complicate the determination of a treatment’s usefulness. A third complicating factor is the duration of treatment use. Chapter 3 features proposed methods for assessing the impact of treatment as a function of time, as well as methods for summarizing the impact of treatment across a range of follow-up times. Chapter 4 addresses the issue of meta-analysis, a commonly used tool for combining information for multiple independent studies, primarily for the purpose of answering a clinical question not suitably addressed by any one single study. This approach has proven highly useful and attractive in recent years, but often relies on parametric assumptions that cannot be verified. We propose a non-parametric approach to meta-analysis, valid in a wider range of scenarios, minimizing concerns over compromised validity.

No description available.

It is of interest that researchers study competing risks in which subjects may fail from any one of K causes. Comparing any two competing risks with covariate effects is very important in medical studies. This thesis develops omnibus tests for comparing cause-specific hazard rates and cumulative incidence functions at specified covariate levels. In the thesis, the omnibus tests are derived under the additive risk model, that is an alternative to the proportional hazard model, with by a weighted difference of estimates of cumulative cause-specific hazard rates. Simultaneous confidence bands for the difference of two conditional cumulative incidence functions are also constructed. A simulation procedure is used to sample from the null distribution of the test process in which the graphical and numerical techniques are used to detect the significant difference in the risks. A melanoma data set is used for the purpose of illustration.

Darbo tikslas- įvertinti hospitalinės infekcijos paplitimą bei valdymo galimybes rajonų ir apskričių ligoninėse. Uždaviniai: 1) įvertinti hospitalinių infekcijų struktūrą ir paplitimą Lietuvos rajonų ir apskričių ligoninėse, 2) nustatyti ir palyginti rizikos veiksnius ir objektus rajoninėse ir apskričių ligoninėse, 3) teikti pasiūlymus hospitalinių infekcijų valdymo tobulinimui. Tyrimo metodika. Tyrimo objektai –bendrosios chirurgijos, ortopedijos- traumatologijos, reanimacijos- intensyvios terapijos, akušerijos – ginekologijos skyriai. Hospitalinių infekcijų paplitimas įvertintas 4 rajonų ligoninėse ir 2 apskričių ligoninėse. Tyrimas buvo atliekamas naudojantis hospitalinių infekcijų registravimo protokolais, kurie buvo ligos istorijose. Už 2005 m. ištirta 2002 hospitalinių infekcijų atvejai. Duomenys apie hospitalinės infekcijos atvejus buvo gretinami su įrašais hospitalinių infekcijų žurnaluose ir pranešimais Visuomenės sveikatos centruose. Tyrimo duomenų matematinė ir statistinė analizė atlikta, naudojantis skaičiuoklės Microsoft EXCEL statistinėmis funkcijomis bei uždavinių analizės posistemės “Data Analysis”funkcijomis. Rezultatai: Tyrime dalyvavusių rajonų ligoninėse hospitalinių infekcijų paplitimas 3,1%; 3,2%; 2,8%; 3,3%, o apskričių – 4,0%; 4,6%. Rizikos veiksnių paplitimas : operacija 24%; intraveninė priemonė 22,9% ; pneumonija 16,8 %, kitos kvėpavimo takų infekcijos 13,9 %. Hospitalinių infekcijų atvejai registracijos žurnaluose ir VSC tirtose rajonų... [toliau žr. visą tekstą] / Aim: to assess the incidence of nosocomial infections and possibilities of their management in district and county hospitals. Objectives: 1) to assess the incidence and structure of nosocomial infections in district and county hospitals in Lithuania, 2) to determine and compare the risk factors of nosocomial infections in district and county hospitals, 3) to develop proposals for the improvement of nosocomial infection management. Methodology. The analysis was carried out in 4 district and 2 county hospitals, at the departments of general surgery, orthopedics and traumatology, reanimation and intensive therapy, obstetrics and gynaecology.. Nosocomial infection registration records presented in case histories served as a primary source of information. 2002 cases of nosocomial infections that occurred in 2005 were investigated. The data of the cases of nosocomial infections were compared with the records in nosocomial infection registers and reports in Public Health Centres. Statistical analysis of the research data was performed applying statistical functions of the Microsoft EXCEL spreadsheet and the functions of the task analysis subsystem Data Analysis. Results: The incidence of nosocomial infections was 3.1%, 3.2%, 2.8%, and 3.3% in the district hospitals, and 4.0%, 4.6% in the county hospitals. The major risk factors were surgery (24%), intravenous implement (22.9%), pneumonia (16.8%), and other respiratory infections (13.9%). The cases of nosocomial infections... [to full text]

Medicinos darbuotojai dėl kasdieninio kontakto su žmogaus organizmo skysčiais priskiriami didžiausios biologinių veiksnių rizikos grupei. Incidentų – mikrotraumų ir ekspozicijos krauju, rizika yra susijusi su kraujo keliu plintančiomis infekcijomis (HBV, HCV, ŽIV). Darbo tikslas: Nustatyti medicinos darbuotojų profesinių biologinių veiksnių riziką ir paplitimą Kauno medicinos universiteto klinikų chirurgijos profilio skyriuose. Tyrimo metodika. Vykdytas retrospektyvinis tyrimas 2006 m. 1-6 mėnesių, duomenys rinkti Kauno medicinos universiteto klinikų chirurgijos profilio skyriuose. Atlikta anketinė apklausa. Išdalintos 347 anoniminės anketos, atsako dažnis 89,6 % (311). Statistiniam duomenų apdorojimui naudotas SPSS 11.0 programinis paketas. Rezultatai. 64,5% respondentų patyrė mikrotraumą, 71,1 % – ekspoziciją biologiniais skysčiais, mikrotraumą, ir ekspoziciją patyrė 39,6% darbuotojų. Visais mikrotraumų atvejais buvo sužeistos rankos, ekspozicijų metu 63% respondentų apsitaškė sveiką odą, 20% – akis. Dažniausiai darbuotojai apsitaškė krauju (60%). Gydytojai mikrotraum��� dažniausiai patyrė operacijų metu (79,3%), slaugytojos – apruošdamos instrumentus (35,1%), pagalbiniai darbuotojai – tvarkydami atliekas (75,8%). Gydytojai dažniausiai susižeidė chirurgine adata (72,4%), slaugytojos – injekcine adata (72,4%), pagalbiniai darbuotojai – stiklu (60,6%). 86% respondentų nebuvo pasiskiepiję HB vakcina. Mikrotraumų metu 14,5%, ekspozicijų metu 5% respondentų asmeninių apsaugos... [toliau žr. visą tekstą] / The health care workers are attributed to the highest biological factors risk group, as they daily come into contact with fluids of human body. Risk of incidents – sharps injuries and blood exposure – is related to the infections, spread by blood (HBV, HCV, HIV). Aim of the study. Determine the professional biological risk factors for health care workers and their incidence in the surgical departments of Kaunas Medical University Hospital. Methods. Retrospective study of 1-6 months of year 2006 was performed; data was collected in the surgical departments of Kaunas Medical University Hospital. Anonymous questionnaire survey was performed. 347 questionnaires were distributed; rate of response was 89.6% (311). SPSS 11.0 software was used for statistical data processing. Results. 64.5% of respondents had experienced sharps injury, 71.1% were exposed to the biological fluids, and 39.6% of workers had experienced the injury and the exposure. The hands were injured during all the sharps injury cases; 63% of respondents were drabbled by blood on the healthy skin and 20 % were drabbled into the eyes during the blood exposure. In most cases worker were drabbled by blood (60%). Physicians mostly experience the sharps injury during the surgery (79.3%), nurses – during the preparation of instruments (35.1%), supporting staff – disposing the waste (75.8%). Commonly physicians were injured by the surgical needle (72.4%), nurses – by needlestick (72.4%), and the supporting staff – by glass... [to full text]

Darbo tikslas – atlikti sergamumo hospitalinėmis infekcijomis, jų rizikos veiksnių, hospitalinių infekcijų sąlygoto mirštamumo bei ekonominį įvertinimą Lietuvos vaikų intensyviosios terapijos skyriuose. Tikslui pasiekti iškelti šie uždaviniai: 1) ištirti sergamumą hospitalinėmis infekcijomis, nustatyti dažniausią jų lokalizaciją bei sukėlėjus; 2) įvertinti hospitalinių infekcijų rizikos veiksnius; 3) nustatyti sergamumo bei rizikos įgyti hospitalines infekcijas pokyčius, įdiegus intervencijos programą; 4) įvertinti hospitalinių infekcijų ir ligos baigties sąsajas; 5) įvertinti hospitalinę infekciją įgijusių ir neįgijusių tiriamųjų gulėjimo trukmę bei gydymo išlaidas ir apskaičiuoti gulėjimo trukmės pailgėjimo dėl įgytos hospitalinės infekcijos sąlygotas išlaidas; 6) įvertinti intervencijos metodo ekonominę naudą, išvengus hospitalinės infekcijos. Perspektyvusis analitinis stebėjimo tyrimas vyko Lietuvos vaikų intensyviosios terapijos skyriuose 2003 - 2007 m. Į tyrimą įtraukti visi nuo 1 mėn. iki 18 m. amžiaus ligoniai, kurie gydėsi VITS > 48 val. Iš viso dalyvavo 1831 tiriamasis. Tyrimo duomenimis, sergamumas hospitalinėmis infekcijomis sudarė 15,0 atvejų 100-ui ligonių arba 24,5 atvejo 1000-čiui lovadienių. Sukurtas ir išbandytas unikalus ventiliacinės pneumonijos profilaktikos priemonių paketas. Išnagrinėtos hospitalinės infekcijos ir ligos baigties sąsajos bei ekonominiai šios problemos aspektai, remiantis šalyje patvirtintais vaikų reanimacijos paslaugų įkainiais... [toliau žr. visą tekstą] / The objectives of the study were as follows: 1) to investigate and to assess the incidence rates of nosocomial infections, their distribution by site and causative microorganisms; 2) to assess the risk factors of nosocomial infections; 3) to evaluate the changes of the risk of acquisition of nosocomial infections and the changes of the incidence of nosocomial infections after the implementation of the intervention programme; 5) to assess the association between nosocomial infection and outcomes; 6) to evaluate the increase of length of stay and the costs of patients with and without nosocomial infections, and to calculate the cost of single case of nosocomial infection and single patient with noscomial infection; 7) to make cost-benefit analysis of the intervention programme. The prospective surveillance study was carried out between March 2003 and December 2007. The paediatric intensive care unit patients aged between 1 month and 18 years and stayed in the units for more than 48 hours were eligible for inclusion in this study. The incidence of 15.0 cases per 100 patients and incidence density of 24.5 cases per 1000 patient-days was observed. Also the unique intervention programme was designed and implemented, which resulted in significant decrease of the incidence rates. No mortality attributable to nosocomial infections was found in the study. The minimal direct costs due to increase in length-of-stay was calculated in the study, as well as benefit of the intervention... [to full text]