Discover the most talked about and latest scientific content & concepts.

Concept: Student's t-test


RNA detection in liquid urine biopsy specimens could be an optimal method for noninvasive diagnostic and prognostic procedures in urologic disorders; however, there are no standardized procedures for implementing it in the clinic. We present a systematic evaluation of the best storage conditions and purification methods using four commercially available extraction kits to purify RNA from void urine. We measured different RNA molecules to select good and stable biomarkers and normalizers for analyses in liquid urine biopsy specimens. We have established a new combined procedure for RNA isolation from urine and found good performance in 25 urine samples from healthy volunteers of both sexes. Associations were tested using the t-test for paired samples, and miRNA specimens were selected as the more stable molecules. Stability analysis was performed, and we found miR193a and miR448 as the best normalizers to be used in this biofluid. This is a highly reproducible method that could be used to evaluate urine samples for diagnostic and prognostic purposes.

Concepts: Scientific method, Medical terms, RNA, Student's t-test, English-language films, Normal distribution, RNA extraction, Z-test


Titanium mesh cranioplasty is routinely used worldwide for skull defect patients given its advantages, such as stability and biocompatibility. However, there are very few reports concerning the treatment of implant-associated scalp infection, which is one of the most common complications. The aim of the study is to retrospectively evaluate a novel operation technique for the treatment of titanium mesh-associated scalp infection post-cranioplasty, namely partial titanium mesh explantation (PTME). A retrospective study was conducted in all patients who underwent surgical treatment for implant-associated scalp infection from January 2012 to September 2016 in our hospital. In total, 17 patients were selected for study analysis among 231 patients who underwent cranioplasty. The treatment success rate of PTME was 85.7%. There was no statistically significant difference in demographics and characteristics except for follow-up length of time between the PTME group and TTME (total titanium mesh explantation) group (Non-paired Student’s t-test, P=0.037). While, The PTME group exhibited a significantly reduced skull defect area post-operation compared with the TTME group (Non-paired Student’s t-test, P=0.002). Moreover, post-PTME skull area also exhibited a significantly reduced skull defect area compared with the pre-cranioplasty area in the same patient (Non-paired Student’s t-test, P=0.006). Compared with traditional surgical treatment of implant-associated scalp infection, PTME combined with strict debridement and antibiotic therapy can cure implant-associated scalp infection. Moreover, PTME could preserve sufficient titanium mesh for brain protection and cosmesis.

Concepts: Statistics, Surgery, Statistical significance, Student's t-test, Normal distribution, Welch's t test, Student's t-distribution, Student's t-statistic


Objectives This study was undertaken to verify the possible modifications caused by hormonal deprivation in the extracellular matrix in the penises of neutered cats. Methods Twenty-seven penises from domestic shorthair cats were collected: 14 samples from intact cats and 13 from neutered cats. Sections were stained with Weigert’s resorcin-fuchsin, hematoxylin and eosin, and picrosirius red. Histomorphometric analysis was performed using light microscopy and image analysis software. The following parameters were analyzed: density of the elastic fibers and collagen fibers in the corpus spongiosum; density of the elastic fibers in the tunica albuginea of the corpus cavernosum and the tunica albuginea of the corpus spongiosum; luminal area of the urethra; area of the corpus spongiosum; area of the corpus cavernosum; and thickness of the urethral epithelium. The data were analyzed using the Shapiro-Wilk test to verify the normal distribution, and groups were compared using Student’s t-test; P <0.05 indicated statistically significant differences. Results Significant differences were observed between intact cats and neutered cats in the density of elastic fibers in the tunica albuginea of the corpus cavernosum (8.13% ± 1.38% vs 3.11% ± 0.66%), tunica albuginea of the corpus spongiosum (4.37% ± 1.08% vs 3.30% ± 1.01%) and corpus spongiosum (6.28% ± 3.03% vs 4.10% ± 2.19%), and density of collagen fibers in the corpus spongiosum (34.11% ± 10.86% vs 44.21% ± 12.72%). Conclusions and relevance The results show a significant decrease in the density of the elastic fibers and a significant increase of the density of the collagen fibers in the corpus spongiosum in neutered animals. This suggests that the compliance of the periurethral region is reduced, and these changes could be a predisposing factor for urethral obstructive disease.

Concepts: Statistics, Statistical significance, Student's t-test, Normal distribution, Cat, Penis, Castration, Neutering


Aims: Over the study years, there was a significant increase in body mass index (BMI) and waist-to-height ratio (WtHR) in middle aged Finnish adults. Methods: Data were obtained from 1033 Finnish adults from the Cardiovascular Risk in Young Finns Study in 2007 and 2011. Cohort study participants wore an Omron Walking Style One (HJ-152R-E) pedometer for five days and were grouped into those who increased, maintained and decreased their steps between 2007 and 2011. Paired samples t-test was used to compare body mass index (BMI) and waist-to-height ratio (WtHR) change values between the change groups in study years. Results: Among study population BMI and WtHR increase between study years was statistically significant (p < 0.001). Only those, who increased their total steps for at least 2000 steps, maintained their BMI in the same level, while people who decreased or maintained their total steps in the same level, BMI and WtHR increased during four years follow-up. Conclusions: This data suggests that increasing steps in middle age is associated with maintaining BMI at the same level.

Concepts: Statistics, Body mass index, Student's t-test, Walking


We aim to determine average volumes of the upper airway, adenoids and tonsils in preterm and term infants and assess for the differences according to weight, sex and ethnicity. The volumes of the upper airways, tonsils and adenoids were measured from brain MR images in 96 (49 preterm and 47 term) infants and compared using a two-tailed t-test (significant at p<0.05). The average volumes are reported for both groups. Term infants showed larger naso- and oropharyngeal volumes (independent of weight, sex, and ethnicity). No differences in hypopharyngeal, adenoidal or tonsillar volumes were found.

Concepts: Magnetic resonance imaging, Lymphatic system, Student's t-test, Respiratory system, According to Jim, Airway, Tonsil, Oropharyngeal airway


The objective of this study was to test the effectiveness of an educational intervention with use of educational technology (flipchart) to promote quality of life (QOL) and treatment adherence in people with hypertension. It was an intervention study of before-and-after type conducted with 116 hypertensive people registered in Primary Health Care Units. The educational interventions were conducted using the flipchart educational technology. Quality of life was assessed through the MINICHAL (lowest score = better QOL) and the QATSH (higher score = better adherence) was used to assess the adherence to hypertension treatment. Both were measured before and after applying the intervention. In the analysis, we used the Student’s t-test for paired data. The average baseline quality of life was 11.66 ± 7.55, and 7.71 ± 5.72 two months after the intervention, showing a statistically significant reduction (p <0.001) and mean of differences of 3.95. The average baseline adherence to treatment was 98.03 ± 7.08 and 100.71 ± 6.88 two months after the intervention, which is statistically significant (p < 0.001), and mean of differences of 2.68. The conclusion was that the educational intervention using the flipchart improved the total score of quality of life in the scores of physical and mental domains, and increased adherence to hypertension treatment in people with the disease.

Concepts: Statistics, Hypertension, Statistical significance, Quality, Educational psychology, Student's t-test, Ronald Fisher, P-value


BACKGROUND: The symptom ‘dizziness’ is common in patients with chronic whiplash related disorders. However, little is known about dizziness in neck pain patients who have not suffered whiplash. Therefore, the purposes of this study are to compare baseline factors and clinical outcomes of neck pain patients with and without dizziness undergoing chiropractic treatment and to compare outcomes based on gender. METHODS: This prospective cohort study compares adult neck pain patients with dizziness (n = 177) to neck pain patients without dizziness (n = 228) who presented for chiropractic treatment, (no chiropractic or manual therapy in the previous 3 months). Patients completed the numerical pain rating scale (NRS) and Bournemouth questionnaire (BQN) at baseline. At 1, 3 and 6 months after start of treatment the NRS and BQN were completed along with the Patient Global Impression of Change (PGIC) scale. Demographic information was also collected. Improvement at each follow-up data collection point was categorized using the PGIC as ‘improved’ or ‘not improved’. Differences between the two groups for NRS and BQN subscale and total scores were calculated using the unpaired Student’s t-test. Gender differences between the patients with dizziness were also calculated using the unpaired t-test. RESULTS: Females accounted for 75% of patients with dizziness. The majority of patients with and without dizziness reported clinically relevant improvement at 1, 3 and 6 months with 80% of patients with dizziness and 78% of patients without dizziness being improved at 6 months. Patients with dizziness reported significantly higher baseline NRS and BQN scores, but at 6 months there were no significant differences between patients with and without dizziness for any of the outcome measures. Females with dizziness reported higher levels of depression compared to males at 1, 3 and 6 months (p = 0.007, 0.005, 0.022). CONCLUSIONS: Neck pain patients with dizziness reported significantly higher pain and disability scores at baseline compared to patients without dizziness. A high proportion of patients in both groups reported clinically relevant improvement on the PGIC scale. At 6 months after start of chiropractic treatment there were no differences in any outcome measures between the two groups.

Concepts: Male, Female, Gender, Sex, Student's t-test, Normal distribution, Chiropractic, Spinal manipulation


Purpose To determine the frequency of, and yield after, provider overrides of evidence-based clinical decision support (CDS) for ordering computed tomographic (CT) pulmonary angiography in the emergency department (ED). Materials and Methods This HIPAA-compliant, institutional review board-approved study was performed at a tertiary care, academic medical center ED with approximately 60 000 annual visits and included all patients who were suspected of having pulmonary embolism (PE) and who underwent CT pulmonary angiography between January 1, 2011, and August 31, 2013. The requirement to obtain informed consent was waived. Each CT order for pulmonary angiography was exposed to CDS on the basis of the Wells criteria. For patients with a Wells score of 4 or less, CDS alerts suggested d-dimer testing because acute PE is highly unlikely in these patients if d-dimer levels are normal. The yield of CT pulmonary angiography (number of positive PE diagnoses/total number of CT pulmonary angiographic examinations) was compared in patients in whom providers overrode CDS alerts (by performing CT pulmonary angiography in patients with a Wells score ≤4 and a normal d-dimer level or no d-dimer testing) (override group) and those in whom providers followed Wells criteria (CT pulmonary angiography only in patients with Wells score >4 or ≤4 with elevated d-dimer level) (adherent group). A validated natural language processing tool identified positive PE diagnoses, with subsegmental and/or indeterminate diagnoses removed by means of chart review. Statistical analysis was performed with the χ(2) test, the Student t test, and logistic regression. Results Among 2993 CT pulmonary angiography studies in 2655 patients, 563 examinations had a Wells score of 4 or less but did not undergo d-dimer testing and 26 had a Wells score of 4 or less and had normal d-dimer levels. The yield of CT pulmonary angiography was 4.2% in the override group (25 of 589 studies, none with a normal d-dimer level) and 11.2% in the adherent group (270 of 2404 studies) (P < .001). After adjustment for the risk factor differences between the two groups, the odds of an acute PE finding were 51.3% lower when providers overrode alerts than when they followed CDS guidelines. Comparison of the two groups including only patients unlikely to have PE led to similar results. Conclusion The odds of an acute PE finding in the ED when providers adhered to evidence presented in CDS were nearly double those seen when providers overrode CDS alerts. Most overrides were due to the lack of d-dimer testing in patients unlikely to have PE. (©) RSNA, 2016.

Concepts: Informed consent, Pulmonary embolism, CT pulmonary angiogram, Decision theory, Student's t-test, Normal distribution, Student's t-distribution, Clinical decision support system


We assess the repeatability and relative validity of a Spanish beverage intake questionnaire for assessing water intake from beverages. The present analysis was performed within the framework of the PREDIMED-PLUS trial. The study participants were adults (aged 55-75) with a BMI ≥27 and <40 kg/m², and at least three components of Metabolic Syndrome (MetS). A trained dietitian completed the questionnaire. Participants provided 24-h urine samples, and the volume and urine osmolality were recorded. The repeatability of the baseline measurement at 6 and 1 year was examined by paired Student's t-test comparisons. A total of 160 participants were included in the analysis. The Bland-Altman analysis showed relatively good agreement between total daily fluid intake assessed using the fluid-specific questionnaire, and urine osmolality and 24-h volume with parameter estimates of -0.65 and 0.22, respectively (R² = 0.20; p < 0.001). In the repeatability test, no significant differences were found between neither type of beverage nor total daily fluid intake at 6 months and 1-year assessment, compared to baseline. The proposed fluid-specific assessment questionnaire designed to assess the consumption of water and other beverages in Spanish adult individuals was found to be relatively valid with good repeatability.

Concepts: Statistics, Nutrition, Assessment, Psychometrics, Student's t-test, Test, Drink, Drinking


Collecting accurate and reliable nutritional data from adolescent populations is challenging, with current methods providing significant under-reporting. Therefore, the aim of the study was to determine the accuracy of a combined dietary data collection method (self-reported weighed food diary, supplemented with a 24-h recall) when compared to researcher observed energy intake in male adolescent soccer players. Twelve Academy players from an English Football League club participated in the study. Players attended a 12 h period in the laboratory (08:00 h-20:00 h), during which food and drink items were available and were consumed ad libitum. Food was also provided to consume at home between 20:00 h and 08:00 h the following morning under free-living conditions. To calculate the participant reported energy intake, food and drink items were weighed and recorded in a food diary by each participant, which was supplemented with information provided through a 24-h recall interview the following morning. Linear regression, limits of agreement (LOA) and typical error (coefficient of variation; CV) were used to quantify agreement between observer and participant reported 24-h energy intake. Difference between methods was assessed using a paired samples t-test. Participants systematically under-reported energy intake in comparison to that observed (p < 0.01) but the magnitude of this bias was small and consistent (mean bias = -88 kcal·day-1, 95% CI for bias = -146 to -29 kcal·day-1). For random error, the 95% LOA between methods ranged between -1.11 to 0.37 MJ·day-1 (-256 to 88 kcal·day-1). The standard error of the estimate was low, with a typical error between measurements of 3.1%. These data suggest that the combined dietary data collection method could be used interchangeably with the gold standard observed food intake technique in the population studied providing that appropriate adjustment is made for the systematic under-reporting common to such methods.

Concepts: Regression analysis, Statistics, Nutrition, Student's t-test, Normal distribution