1,721,011 research outputs found
Utilizzo degli archivi elettronici sanitari nell’epidemiologia analitica: aspetti metodologici del disegno dello studio e dell’analisi statistica dei dati applicati alla stima del rischio di un evento clinico raro
No full textLa crescente disponibilità di banche dati informatizzate sanitarie ha reso gli studi osservazionali uno strumento potente a fornire evidenze scientifiche. Limiti connessi ai database e distorsioni da cui possono essere affetti questi studi, possono compromettere i risultati.
Questa tesi analizza i metodi di correzione da utilizzare in fase di disegno e di analisi statistica. Alcune di essi sono stati applicati ad uno studio volto a valutare il rischio di sviluppare un evento raro, danno renale acuto (DRA) da somministrazione di mezzo di contrasto iodato (MCI).
A tal fine sono stati applicati il disegno di coorte e di caso-controllo innestato nella coorte, utilizzando le schede di dimissioni ospedaliere della regione Marche.
La coorte comprendeva 29925 soggetti a cui era stata somministrato il MCI durante il 2008-2011; sono stati individuati 324 casi di DRA in totale, per 129 di questi il tempo trascorso dalla data di somministrazione di MCI era <7 giorni, perciò associati al DRA. Il rischio di sviluppare DRA da MCI risultava 0.43%. Soggetti di età superiore a 65 anni, che soffrivano di una malattia del sistema genitourinario sono risultati a maggior rischio.
Nello studio caso-controllo innestato, i 324 casi sono stati appaiati a 1258 controlli. L’esposizione al MCI e le malattie del sistema genitourinario erano significativamente associate ad un maggior rischio di DRA. L’effetto dell’esposizione sullo sviluppo del DRA riduceva il rischio nei soggetti con età superiore a 65 anni e in quelli con più di una somministrazione, mentre aumentava in quelli con una patologia diversa dalle malattie genitourinarie e del sistema circolatorio.
Lo studio ha permesso di stimare il rischio di un evento raro e l’effetto dei fattori ad esso associati; rappresenta, altresì, una concreta applicazione della metodologia epidemiologica attuale, particolarmente attenta alle problematiche connesse all’utilizzo di una fonte di dati potente ma che al contempo richiede cautela e cognizione di causa nella sua applicazione
Do machine learning methods solve the main pitfall of linear regression in dental age estimation?
Full text linkIntroduction: Age estimation is crucial in forensic and anthropological fields. Teeth, are valued for their resilience to environmental factors and their preservation over time, making them essential for age estimation when other skeletal remains deteriorate. Recently, Machine Learning algorithms have been used in age estimation, demonstrating high levels of accuracy. However, their precision with respect to the trend of age estimation error, typical in some traditional methods like linear regression, has not been thoroughly investigated. Aim: To evaluate and compare the performance of frequently used Machine Learning-assisted methods against two traditional age estimation methods, linear regression and the Segmented Normal Bayesian Calibration model. Methods: Overall, 1.949 orthopantomographs from black and white South African children aged 5–14 years, with 49 % males, were evaluated. The performance of Random Forest, Support Vector Regression, K-Nearest Neighbors and the Gradient Boosting Method were compared against traditional linear regression and the Segmented Normal Bayesian Calibration model. The comparison was based on accuracy measures, including Mean Absolute Error and Root Mean Squared Error, and precision measures, including the Inter-Quartile Range of the error distribution and the slope of the estimated age error relative to chronological age. Results: The Machine Learning methods outperformed linear regression and the Segmented Normal Bayesian Calibration models in terms of accuracy, although the differences were small. Gradient Boosting Method and Support Vector Regression achieved the highest levels of accuracy (Mean Absolute Error: 0.69 years, Root Mean Squared Error: 0.85 years). All Machine Learning methods and linear regression exhibited significant bias in residuals, whereas the Segmented Normal Bayesian Calibration model showed no significant bias. Gender-stratified analyses revealed similar results in terms of the accuracy and precision of all considered models. Conclusion: Although Machine Learning methods demonstrate high levels of accuracy, they may be prone to trends in error distribution when estimating dental age. Evaluating this error is crucial and should be an integral part of model performance evaluation. Future research should aim to improve accuracy while rigorously addressing systematic biases
Bayesian calibration for forensic age estimation.
No full textForensic medicine is increasingly called upon to assess the age of individuals. Forensic age estimation is mostly required in relation to illegal immigration and identification of bodies or skeletal remains. A variety of age estimation methods are based on dental samples and use of regression models, where the age of an individual is predicted by morphological tooth changes that take place over time. From the medico-legal point of view, regression models, with age as the dependent random variable entail that age tends to be overestimated in the young and underestimated in the old. To overcome this bias, we describe a new full Bayesian calibration method (asymmetric Laplace Bayesian calibration) for forensic age estimation that uses asymmetric Laplace distribution as the probability model. The method was compared with three existing approaches (two Bayesian and a classical method) using simulated data. Although its accuracy was comparable with that of the other methods, the asymmetric Laplace Bayesian calibration appears to be significantly more reliable and robust in case of misspecification of the probability model. The proposed method was also applied to a real dataset of values of the pulp chamber of the right lower premolar measured on x-ray scans of individuals of known age
Stima del rischio di danno renale acuto da mezzo di contrasto mediante l’utilizzo di banche di dati amministrativi
No full text
Epidemiology, clinical characteristics, and outcome of candidemia in a tertiary referral center in Italy from 2010 to 2014
No full textPURPOSE:
We evaluated the epidemiology, clinical characteristics and outcome of candidemia in a single institution from 2010 to 2014.
METHODS:
A retrospective observational study of all cases of candidemia was carried out at a University Hospital in Central Italy including five intensive care units (ICUs), 11 medical and 11 surgical wards. Data regarding demographic characteristics and clinical risk factors were collected from the patient's medical records. Antifungal susceptibility testing was performed and MIC results were interpreted according to species-specific clinical breakpoints.
RESULTS:
A total of 270 episodes of candidemia were identified. Overall incidence rate was 1.5 episodes/1000 hospital admissions. Although Candida albicans represented the most commonly isolated species, its percentage significantly decreased from 68 to 48 % (p = 0.040). The overall 30-day mortality was 35 %. The variables independently associated with a significant higher risk of mortality were: older age; being hospitalized in ICU or in medical wards vs surgical wards; being infected with C. albicans vs other species; the occurrence of septic shock, pneumonia and acute renal failure; the presence of a solid organ tumor or a chronic pulmonary disease. Conversely, an appropriate treatment was confirmed to be significantly associated with a lower risk of mortality. The overall resistance was low and it was noted only among triazoles.
CONCLUSIONS:
Our study shows that candidemia is a significant source of morbidity and mortality. The identification of risk factors associated with mortality along with the knowledge of local susceptibility may lead to a better management in terms of preventive and therapeutic measures
Functional outcomes after TEM in patients with complete clinical response after neoadjuvant chemoradiotherapy
Full text linkBackground In patients who exhibit a complete clinical response after radio-chemotherapy for rectal cancer, the standard surgical approach might constitute overtreatment. The aim of this study is to analyse the outcomes of
anorectal function and quality of life after transanal endoscopic microsurgery (TEM) in irradiated patients with complete clinical response. Patients and methods Between 2007 and 2014, 84 patients who were diagnosed with stage T2–T3–T4 N0 rectal cancer before chemoradiotherapy showed a complete clinical response to neoadjuvant therapy and underwent TEM. All patients were evaluated before and 1 year after TEM using the Cleveland Clinic Florida Fecal Incontinence Score (CCF-FIS) questionnaire to determine the impact of this surgical technique on the degree of faecal continence. To assess the quality of life of patients after surgery, we administered the Fecal Incontinence Quality of Life Scale. Results Twenty-three patients exhibited a worse incontinence status after surgical intervention (27.4; 95% CI 18.2–38.2). These patients experienced a median positive absolute variation in the CCF-FIS of four points (95% CI 3.5–4.5; p.001). Female sex and age showed a significant correlation with the worsening of continence status. Scores on the Fecal Incontinence Quality of Life Index Scale did not show a significant difference efore and after TEM. Conclusions TEM may be an alternative treatment for patients with rectal cancer who exhibit a complete clinical response to neoadjuvant chemoradiotherapy because it offers the possibility to achieve a full hickness excision of the rectal wall. TEM also allows the identification of any residual disease and provides optimal quality of life and functional results
The environmental and occupational influence of pesticides on male fertility: A systematic review of human studies
Full text linkBackground: The environment plays a key role in male infertility, changing the incidence in various populations, and pesticides are one of the most studied hazards. The use of the latter has never decreased, jeopardizing the safety of workers and the general population. Objective: Our purpose was to summarize the results of studies discussing the association between pesticides and male fertility. Methods: A comprehensive literature search was performed through MEDLINE via PubMed, Scopus, and Web of Science. Only human studies were considered. Semen parameters and DNA integrity were considered to evaluate the effect of pesticides on men. Results: A total of 64 studies that investigated their impact in terms of semen parameters (51 studies) and chromatin and DNA integrity (25 studies) were included. The most frequently affected parameters were total sperm count, sperm motility, and sperm morphology, although a reduction in ejaculate volume and concentration occur in several cases. A tangible worsening of semen quality was associated with organochlorines and organophosphates. Furthermore, pesticide exposure, especially pyrethroids, was related to a higher DNA fragmentation index and chromosome aneuploidy in most articles. Conclusion: The epidemiological evidence supports the association between pesticides and male fertility for workers and the exposed population in terms of semen quality, DNA fragmentation, and chromosome aneuploidy
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