P-Values and Power in Orthopedic Research: Myths and Reality

The results of statistical tests in orthopedic studies are typically reported using P-values. If a P-value is smaller than the pre-determined level of significance (eg, < .05), the null hypothesis is rejected in support of the alternative. This automaticity in interpreting statistical results without consideration of the power of the study has been denounced over the years by statisticians, since it can potentially lead to misinterpretation of the study conclusions. In this paper, we review fundamental misconceptions and misinterpretations of P-values and power, along with their connection with confidence intervals, and we provide guidelines to orthopedic researchers for evaluating and reporting study results. We provide real-world orthopedic examples to illustrate the main concepts. Please visit the following https://youtu.be/bdPU4luYmF0 for videos that explain the highlights of the paper in practical terms.     

彩色多普勒超声诊断卵巢肿瘤蒂扭转的临床意义

目的：探讨彩色多普勒超声诊断卵巢肿瘤蒂扭转的临床意义。方法方便选取2012―2015年该院收治的58例疑似卵巢肿瘤蒂扭转患者作为观察目标，入选病例均应用彩色多普勒超声进行检查，并将检查结果同术后病理检查结果进行比较。结果58例患者中，术后病理证实卵巢肿瘤蒂扭转者51例，彩色多普勒超声共确诊49例，检查准确率为96.1%；囊壁增厚、腹腔或盆腔积液、可见混合型团块是卵巢肿瘤蒂扭转的主要彩超表现。结论卵巢肿瘤蒂扭转应用彩色多普勒超声诊断，可显著提高诊断准确率，具有积极的临床使用和推广价值。     

Rotavirus,vaccine failure or diagnostic error?

Immunochromatography (ICG) is highly used in clinical settings for rotavirus (RV) diagnosis. The specificity of the tests differs by brand type and is not 100%, therefore its use when the prevalence of the disease is low (i.e. in vaccinated children) may result in a proportion of false positive diagnoses.In some areas, vaccine effectiveness studies or surveillance is done using ICG. Our objective was to estimate the validity of ICG test in vaccinated children, and estimate the number of false positive results in the Valencian Region of Spain, where all RV infections are diagnosed using ICG and are not confirmed by PCR.Population based registries were used to identify all results from the RV antigen tests performed between January 2008 and June 2012 in children under 37 months. Hospitalization and vaccination status of the patients were obtained by linking different databases through a unique identification number. The Positive Predictive Value of the ICG test depending on the vaccination status of the child, hospitalization and the rotavirus season was estimated by a Bayesian model of latent classes.Of the 48,833 tests with valid results, 9429 were done in vaccinated children, and of those 3963 (42%) during the rotavirus season. The prevalence of positive results in vaccinated varied from 2.9 to 21.4% of the tests depending on the hospitalization and seasonality. The estimated PPV also varied from 27.1 to 84.6% when stratified by these two parameters. Globally it is calculated that approximately 267 out of the 520 (51.3%) positives in vaccinated children were false positive tests.The large percentage of false positives, due to an excessive number of tests in vaccinated and out of the RV season, if interpreted as vaccine failures, can cause a loss of confidence in the vaccine and lower the estimates of vaccine effectiveness.     

An Environmental Scan of the National and Provincial Diagnostic Reference Levels in Canada for Common Adult Computed Tomography Scans

Several regulatory bodies have agreed that low-dose radiation used in medical imaging is a weak carcinogen that follows a linear, non-threshold model of cancer risk. While avoiding radiation is the best course of action to mitigate risk, computed tomography (CT) scans are often critical for diagnosis. In addition to the as low as reasonably achievable principle, a more concrete method of dose reduction for common CT imaging exams is the use of a diagnostic reference level (DRL). This paper examines Canada's national DRL values from the recent CT survey and compares it to published provincial DRLs as well as the DRLs in the United Kingdom and the United States of America for the 3 most common CT exams: head, chest, and abdomen/pelvis. Canada compares well on the international scale, but it should consider using more electronic dose monitoring solutions to create a culture of dose optimization.     

Steep Decrease of Gender Difference in DSM-IV Alcohol Use Disorder: A Comparison of Two Nation-wide Surveys Conducted 10 Years Apart in Korea

While decreasing trend in gender differences in alcohol use disorders was reported in Western countries, the change in Asian countries is unknown. This study aims to explore the shifts in gender difference in alcohol abuse (AA) and dependence (AD) in Korea. We compared the data from two nation-wide community surveys to evaluate gender differences in lifetime AA and AD by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Face-to-face interviews using the Composite International Diagnostic Interview (CIDI) were applied to all subjects in 2001 (n=6,220) and 2011 (n=6,022). Male-to-female ratio of odds was decreased from 6.41 (95% CI, 4.81-8.54) to 4.37 (95% CI, 3.35-5.71) for AA and from 3.75 (95% CI, 2.96-4.75) to 2.40 (95% CI, 1.80-3.19) for AD. Among those aged 18-29, gender gap even became statistically insignificant for AA (OR, 1.59; 95% CI, 0.97-2.63) and AD (OR, 1.18; 95% CI, 0.80-2.41) in 2011. Men generally showed decreased odds for AD (0.55; 95% CI, 0.45-0.67) and women aged 30-39 showed increased odds for AA (2.13; 95% CI 1.18-3.84) in 2011 compared to 2001. Decreased AD in men and increased AA in women seem to contribute to the decrease of gender gap. Increased risk for AA in young women suggests needs for interventions.     

Characteristics of Adolescents with Differing Polycystic Ovary Syndrome Phenotypes

Study ObjectiveTo analyze clinical, metabolic, hormonal, and ultrasound characteristics of adolescents with polycystic ovary syndrome phenotypes.DesignWe performed a retrospective analysis of quality improvement data. We divided patients according to phenotype on the basis of clinical or biochemical diagnosis of hyperandrogenism (HA), irregular menstruation (IM), and presence or absence of polycystic ovarian morphology (PCOM) on pelvic ultrasound (PUS) images, if obtained. The 5 resulting groups were: (1) HA/IM/normal PUS, n = 28; (2) HA/PCOM, n = 10; (3) IM/PCOM, n = 18; (4) HA/IM/PCOM, n = 40; and (5) HA/IM/no PUS obtained, n = 80. We compared parameters between groups using the nonparametric Wilcoxon rank sum test.SettingBoston Children's Hospital, 2012-2016.ParticipantsOne hundred seventy-six girls and young women aged 11-25 years.InterventionsNone.Main Outcome Measures(1) Clinical, metabolic, and hormonal characteristics; and (2) PUS measurements.ResultsGroups with HA had significantly higher acne scores, Ferriman-Gallwey scores, and total and free testosterone concentrations than groups without HA. Significant differences in hemoglobin A1c were found between the IM/PCOM and HA/IM/PCOM groups (5.1% vs 5.3%; P = .01) and the IM/PCOM and HA/IM/no PUS groups (5.1% vs 5.3%; P < .01). In patients who had ultrasound performed, 49/94 (52.1%) met PCOM criteria on the basis of ovarian size, 37/94 (39.4%) on the basis of follicle number, and 27/94 (28.7%) on both; 10/94 (10.5)% had incidental findings on ultrasound, with 2 patients requiring further management.ConclusionLimited differences in clinical, metabolic, and hormonal characteristics exist between adolescents with different phenotypes of polycystic ovary syndrome, and are mostly related to the presence or absence of HA. Of patients with ultrasound examinations, only 2 had clinically actionable incidental findings.