Bayes pulmonary embolism assisted-diagnosis: a new expert system for clinical use

Background: The diagnosis of pulmonary embolism demands flexible decision models, both for the presence of clinical confounders and for the variability of local diagnostic resources. As Bayesian networks fully meet this requirement, Bayes Pulmonary embolism Assisted Diagnosis (BayPAD), a probabilistic expert systems focused on pulmonary embolism, was developed. Methods: To quantitatively validate and improve BayPAD, the system was applied to 750 patients from a prospective study done in an Italian tertiary hospital where the true pulmonary embolism status was confirmed using pulmonary angiography or ruled out with a lung scan. The proportion of correct diagnoses made by BayPAD (accuracy) and the correctness of the pulmonary embolism probabilities predicted by the model (calibration) were calculated. The calibration was evaluated according to the Cox regression-calibration model. Results: Before refining the model, accuracy was 88.6%. Once refined, accuracy was 97.2% and 98%, respectively, in the training and validation samples. According to Cox analysis, calibration was satisfactory, despite a tendency to exaggerate the effect of the findings on the probability of pulmonary embolism. The lack of some investigations (like Spiral computed tomographic scan and Lower limbs doppler ultrasounds) in the pool of available data often prevents BayPAD from reaching the diagnosis without invasive procedures. Conclusions: BayPAD offers clinicians a flexible and accurate strategy to diagnose pulmonary embolism. Simple to use, the system performs case-based reasoning to optimise the use of resources available within a particular hospital. Bayesian networks are expected to have a prominent role in the clinical management of complex diagnostic problems in the near future

Modeling The Fluorescence Of Protein-embedded Tryptophans With Ab Initio Multiconfigurational Quantum Chemistry: The Limiting Cases Of Parvalbumin And Monellin

We show that a quantum-mechanics/molecular-mechanics strategy based on ab initio (i.e., first principle) multiconfigurational perturbation theory can reproduce the spectral properties of a tryptophan residue embedded in the contrasting hydrophobic and hydrophilic environments of parvalbumin and monellin, respectively. We show that the observed absorption and emission energies can be reproduced with a less than 3 kcal mol(-1) error. The analysis of the computed emission energies based on a protein disassembly scheme and protein electrostatic potential mapping allows for a detailed understanding of the factors modulating the tryptophan emission. It is shown that for rnonellin, where the tryptophan is exposed to the solvent, the fluorescence wavelength is controlled not only by the distribution of the point charges of the protein-solvent environment but also by specific hydrogen bonds and, most important, by the environment-induced change in chromophore structure. In contrast, in parvalbumin, where the chromophore is embedded in the protein core, the structure and emission maxima are the same as those of an isolated 3-methylindole fluorophore. Consistently, we find that in parvalbumin the solvation does not change significantly the computed emission energy

Prevalence of comorbidities according to predominant phenotype and severity of chronic obstructive pulmonary disease

BACKGROUND: In addition to lung involvement, several other diseases and syndromes coexist in patients with chronic obstructive pulmonary disease (COPD). Our purpose was to investigate the prevalence of idiopathic arterial hypertension (IAH), ischemic heart disease, heart failure, peripheral vascular disease (PVD), diabetes, osteoporosis, and anxious depressive syndrome in a clinical setting of COPD outpatients whose phenotypes (predominant airway disease and predominant emphysema) and severity (mild and severe diseases) were determined by clinical and functional parameters. METHODS: A total of 412 outpatients with COPD were assigned either a predominant airway disease or a predominant emphysema phenotype of mild or severe degree according to predictive models based on pulmonary functions (forced expiratory volume in 1 second/vital capacity; total lung capacity %; functional residual capacity %; and diffusing capacity of lung for carbon monoxide %) and sputum characteristics. Comorbidities were assessed by objective medical records. RESULTS: Eighty-four percent of patients suffered from at least one comorbidity and 75% from at least one cardiovascular comorbidity, with IAH and PVD being the most prevalent ones (62% and 28%, respectively). IAH prevailed significantly in predominant airway disease, osteoporosis prevailed significantly in predominant emphysema, and ischemic heart disease and PVD prevailed in mild COPD. All cardiovascular comorbidities prevailed significantly in predominant airway phenotype of COPD and mild COPD severity. CONCLUSION: Specific comorbidities prevail in different phenotypes of COPD; this fact may be relevant to identify patients at risk for specific, phenotype-related comorbidities. The highest prevalence of comorbidities in patients with mild disease indicates that these patients should be investigated for coexisting diseases or syndromes even in the less severe, pauci-symptomatic stages of COPD. The simple method employed to phenotype and score COPD allows these results to be translated easily into daily clinical practice

Efficacy and safety of once-daily fluticasone furoate/vilanterol (100/25 mcg) versus twice-daily fluticasone propionate/salmeterol (250/50 mcg) in COPD patients

SummaryBackgroundFluticasone furoate/vilanterol (FF/VI) is an inhaled corticosteroid/long-acting beta2-agonist (ICS/LABA), recently approved as once-daily maintenance therapy for COPD. We compared the lung function effects of FF/VI with those of twice-daily fluticasone propionate/salmeterol (FP/SAL).MethodsThree 12 week studies comparing FF/VI and FP/SAL were conducted. Patients aged ≥40 years with moderate-to-very severe COPD were randomized to receive double-blind, double-dummy FF/VI 100/25 mcg once-daily, or FP/SAL 250/50 mcg twice-daily for 12 weeks following a 2 week placebo run-in period. The primary endpoint of each study was change from baseline trough in 0–24 h weighted mean FEV1 (wmFEV1) on Day 84. Safety was also assessed.ResultsIn Study 1 (HZC113109) (intent-to-treat n: FF/VI = 260; FP/SAL = 259), the increase from baseline in 0–24 h wmFEV1 was significantly greater with FF/VI than FP/SAL (Δ80 mL, P < 0.001). In Study 2 (HZC112352) (intent-to-treat n: FF/VI = 259; FP/SAL = 252) and Study 3 (RLV116974) (intent-to-treat n: FF/VI = 412; FP/SAL = 416), the increase from baseline in 0–24 h wmFEV1 was not significantly greater with FF/VI than FP/SAL (Δ29 mL, P = 0.267; Δ25 mL, P = 0.137). The treatment difference was statistically but not clinically significant in a pooled analysis (Δ41 mL, P < 0.001). Pooled adverse events (FF/VI 27%; FP/SAL 28%) and serious adverse events (FF/VI 2%; FP/SAL 3%) were similar between treatments.ConclusionsOur data suggest that once-daily FF/VI 100/25 mcg provides FEV1 improvement in COPD that is at least comparable with that conferred by twice-daily FP/SAL 250/50 mcg, although interpretation is limited by differences in individual study outcomes. The safety profiles of FF/VI 100/25 mcg and FP/SAL 250/50 mcg are similar.Clinical trial registrationclinicaltrials.gov: NCT01323634; NCT01323621; NCT01706328. GlaxoSmithKline study codes: HZC113109; HZC112352; RLV116974