When evaluating a novel diagnostic examination for clinical use, it should be compared with a reference standard, defined as the best available examination, which may include clinical and laboratory criteria. The novel examination and reference standard's results are usually presented in the form of a 2×2 table, which allows calculation of sensitivity, specificity and accuracy. It has been recommended that the measures of statistical uncertainty should be reported, such as the 95% confidence interval, when evaluating the accuracy of diagnostic examinations. Comparing the difference in sensitivity or specificity of a novel examination with the reference standard is important when evaluating its usefulness. The McNemar χ² test, used to compare discordance of two dichotomous responses, can be applied for this purpose. However, applying the McNemar test to a 2×2 table for comparing the accuracy of examinations is not recommended, since this test is sensitive to the proportion of positive versus negative subjects. Moreover, if the novel examination has higher sensitivity than the one considered as the reference standard, constructing a classic 2×2 table would result in low specificity of the novel examination. Thus, in order to compare sensitivities and specificities between examinations, this table is inappropriate and an independent reference standard is necessary. In this article, we propose the use of the McNemar χ² test to compare sensitivities between examinations using a 2×2 table exclusively among diseased patients, defined by a set of criteria and follow‐up of patients. Likewise, specificities can be compared applying the McNemar test among healthy individuals.

Aim. To assess the epidemiological and clinical factors that influence the prognosis of oral and oropharyngeal squamous cell carcinoma (SCC). Methods. One hundred and twenty-one cases of oral and oropharyngeal SCC were selected. The survival curves for each variable were estimated using the Kaplan-Meier method. The Cox regression model was applied to assess the effect of the variables on survival. Results. Cancers at an advanced stage were observed in 103 patients (85.1%). Cancers on the tongue were more frequent (23.1%). The survival analysis was 59.9% in one year, 40.7% in two years, and 27.8% in 5 years. There was a significant low survival rate linked to alcohol intake (p=0.038), advanced cancer staging (p=0.003), and procedures without surgery (p<0.001). When these variables were included in the Cox regression model only surgery procedures (p=0.005) demonstrated a significant effect on survival. Conclusion. The findings suggest that patients who underwent surgery had a greater survival rate compared with those that did not. The low survival rates and the high percentage of patients diagnosed at advanced stages demonstrate that oral and oropharyngeal cancer patients should receive more attention.

The aim was to evaluate three regions of reference (Björk, Modified Björk and mandibular Body) for mandibular registration testing them in a patients’ CBCT sample. Mandibular 3D volumetric label maps were built from CBCTs taken before (T1) and after treatment (T2) in a sample of 16 growing subjects and labeled with eight landmarks. Registrations of T1 and T2 images relative to the different regions of reference were performed, and 3D surface models were generated. Seven mandibular dimensions were measured separately for each time-point (T1 and T2) in relation to a stable reference structure (lingual cortical of symphysis), and the T2-T1 differences were calculated. These differences were compared to differences measured between the superimposed T2 (generated from different regions of reference: Björk, Modified Björk and Mandibular Body) over T1 surface models. ICC and the Bland-Altman method tested the agreement of the changes obtained by nonsuperimposition measurements from the patients’ sample, and changes between the overlapped surfaces after registration using the different regions of reference. The Björk region of reference (or mask) did work properly only in 2 of 16 patients. Evaluating the two other masks (Modified Björk and Mandibular body) on patients’ scans registration, the concordance and agreement of the changes obtained from superimpositions (registered T2 over T1) compared to results obtained from non superimposed T1 and T2 separately, indicated that Mandibular Body mask displayed more consistent results. The mandibular body mask (mandible without teeth, alveolar bone, rami and condyles) is a reliable reference for 3D regional registration.

Background: Acute kidney injury (AKI) is frequent in cirrhotic patients but its best definition is unclear. Recently, the Acute Kidney Injury Network (AKIN) proposed criteria to define AKI. The aims of this study were to apply AKIN criteria to cirrhotic patients with ascites and to evaluate its association to hospital mortality. Study: In this retrospective study, cirrhotic patients with ascites admitted to a university hospital in Brazil between November 2003 and December 2007 were included. AKIN criteria were applied in the first 48 hours of hospitalization, considering 2 values of creatinine in this period. Association of AKI at admission and hospital mortality was analyzed. Results: Of the 198 patients in the study, 91 (46%) presented AKI at hospital admission. Overall hospital mortality was 40.4%. Patients without AKI had a hospital mortality rate of 29.9%, whereas the same rate for patients with this complication was 52.7% (odds ratio=2.6; 95% confidence interval, 1.5-4.7; P=0.001). In a logistic regression analysis, 4 variables were independently associated to hospital mortality: infection, hepatic encephalopathy, Child score, and AKI. A receiver operating characteristic curve analysis revealed that the variation in creatinine proposed by AKIN had the best combination of sensitivity and specificity in relation to hospital mortality. Conclusions: In cirrhotic patients with ascites, prevalence of AKI at hospital admission is high. Patients with renal dysfunction defined by AKIN have significant higher hospital mortality. AKIN criteria are useful in cirrhotic patients with ascites, as it identifies earlier patients with worse prognosis.