P value and the theory of hypothesis testing: an explanation for new researchers

Assessing the antiviral activity of antimicrobial peptides Caerin1.1 against PRRSV in Vitro and in Vivo

The Porcine reproductive and respiratory syndrome (PRRS) causes severe financial losses to the global swine industry. Due to continuous virus evolution, the protection against the PRRS provided by current vaccines is limited. In order to find new antiviral strategies, this study investigated the antiviral potential of antimicrobial peptides (AMPs) against PRRSV. Given the diversity of PRRSV strains and the limited effectiveness of existing vaccines in controlling PRRSV, this study evaluated the inhibitory effects of KLAK, Cecropin B, Piscidin1, and Caerin1.1 on 3 strains of PRRSV (lineage 5 classical strain, lineage 8 highly pathogenic strain, and lineage 1 NADC30-like strain). Caerin1.1 exhibited significant dose-dependent antiviral activity, with an effective concentration (EC50) of 7.5 μM. Caerin1.1 effectively inhibited PRRSV replication when added before or in early infection but showed reduced effectiveness when added in late infection, indicating its potential involvement in targeting early transcription mechanisms of viral RNA polymerase and significantly upregulating cytokine gene expression. In the NADC30 strain-based animal infection model, Caerin1.1 treatment significantly reduced lung viral loads and inflammation in the lungs of PRRSV-infected pigs, with a mortality rate of 0 % (0/5) in the treated group compared to 66.67 % (4/6) in the untreated group, indicating a reduction in the mortality rate. Additionally, compared with the untreated group, the Caerin1.1-treated group showed significant improvements, such as lighter fever, more daily weight gain, less clinical symptoms, less viral load in blood, and less virus oral shedding (P < 0.05). These findings reveal the potential of antimicrobial peptides as PRRSV therapeutic agents and suggest that Caerin1.1 is a promising candidate for a novel anti-PRRSV drug.

Beyond 'statistical significance': A nontechnical primer of Bayesian statistics and Bayes factors for health researchers

RATIONALE

Hypothesis testing is integral to health research and is commonly completed through frequentist statistics focused on computing p values. p Values have been long criticized for offering limited information about the relationship of variables and strength of evidence concerning the plausibility, presence and certainty of associations among variables. Bayesian statistics is a potential alternative for inference-making. Despite emerging discussion on Bayesian statistics across various disciplines, the uptake of Bayesian statistics in health research is still limited.

AIM

To offer a primer on Bayesian statistics and Bayes factors for health researchers to gain preliminary knowledge of its use, application and interpretation in health research.

METHODS

Theoretical and empirical literature on Bayesian statistics and methods were used to develop this methodological primer.

CONCLUSIONS

Using Bayesian statistics in health research without a careful and complete understanding of its underlying philosophy and differences from frequentist testing, estimation and interpretation methods can result in similar ritualistic use as done for p values.

IMPLICATIONS

Health researchers should supplement frequentists statistics with Bayesian statistics when analysing research data. The overreliance on p values for clinical decisions making should be avoided. Bayes factors offer a more intuitive measure of assessing the strength of evidence for null and alternative hypothesis.

"Trend" Statement Use in the Orthopaedic Literature

INTRODUCTION

For research to effectively guide clinical decision making, appropriate interpretation of data is paramount. The P -value is a useful tool for guiding the interpretation of data. However, despite its utility, the P -value is not without limitations. Of particular concern is the use of "trend statements" to describe non-statistically significant findings, a practice which introduces subjectivity and variability into data interpretation and can lead to the drawing of undue conclusions.

METHODS

An audit of original research articles published from January 2022 to December 2022 in four high-impact orthopaedic journals was conducted. The selected journals were queried to identify instances in which a non-statistically significant result was labeled as a "trend." The use of trend statements and associated information was recorded and analyzed.

RESULTS

One thousand two hundred sixty articles were included in the analysis. 81 articles (6.4%) included a trend statement to describe a non-statistically significant result. Only two articles (2.5%) formally defined what constituted a trend. In 28.8% of cases, the associated P -value was > 0.10.

DISCUSSION

Trend statements are used to describe non-statistically significant findings with moderate frequency in the orthopaedic literature. Given the potentially misleading effects of trend statements, efforts should be made to mitigate their use. If trend statements are to be used, attention should be paid to defining what constitutes a "trend", explicitly acknowledging the lack of statistical significance of the finding to which the trend statement refers, and avoiding drawing undue conclusions from non-statistically significant data.

Calculation of the minimal clinically important difference in operated patients with adult spine deformity: advantages of the ROC method and significance of prevalence in threshold selection

PURPOSE

The Minimal Clinically Important Difference (MCID) is crucial to evaluate management outcomes, but different thresholds have been obtained in different works. Part of this variability is due to measurement error and influence of the database, both essential for calculating the MCID. The aim of this study was to introduce the association of the ROC method in the anchor-based MCID calculation for ODI, SRS-22r, and SF-36, to objectively set the threshold for the anchor-based MCID in an adult spine deformity (ASD) population.

METHODS

Multicentric study based on a prospective database of consecutively operated ASD patients. An anchor question was used to assess patients' quality of life after surgery. Different approaches were used to calculate the MCID and then compared: SEM (Standard Error of Measurement), MDC (Minimal Detectable Change), and anchor-based MCID with ROC method.

RESULTS

516 patients were included. Those who responded with 6 and 7 to the anchor question were considered improved. The MCID ranges obtained with the ROC method exhibited the lowest variability. Prediction error rates ranged from 31% (SRS-22r) to 41% (SF-36 MCS). The MCID ranges spanned between 12 and 15 for ODI, 0.6 and 0.73 for SRS-22r, 6.62 and 7.41 for SF-36 PCS, and between 2.69 and 5.63 for SF-36 MCS.

CONCLUSION

The ROC method proposes an MCID range with error rate, and can objectively determine the threshold for distinguishing improved and non-improved patients. As the MCID correlates with the utilized database and error of measurement, each study should compute its own MCID for each PROM to allow comparison among different publications.

LEVEL OF EVIDENCE

II.

Key HPI axis receptors facilitate light adaptive behavior in larval zebrafish

The vertebrate stress response (SR) is mediated by the hypothalamic-pituitary-adrenal (HPA) axis and contributes to generating context appropriate physiological and behavioral changes. Although the HPA axis plays vital roles both in stressful and basal conditions, research has focused on the response under stress. To understand broader roles of the HPA axis in a changing environment, we characterized an adaptive behavior of larval zebrafish during ambient illumination changes. Genetic abrogation of glucocorticoid receptor (nr3c1) decreased basal locomotor activity in light and darkness. Some key HPI axis receptors (mc2r [ACTH receptor], nr3c1), but not nr3c2 (mineralocorticoid receptor), were required to adapt to light more efficiently but became dispensable when longer illumination was provided. Such light adaptation was more efficient in dimmer light. Our findings show that the HPI axis contributes to the SR, facilitating the phasic response and maintaining an adapted basal state, and that certain adaptations occur without HPI axis activity.

Randomized Controlled Trials Comparing Bone-Patellar Tendon-Bone Versus Hamstring Tendon Autografts in Anterior Cruciate Ligament Reconstruction Surgery Are Statistically Fragile: A Systematic Review

PURPOSE

To assess the statistical fragility of recently published randomized controlled trials (RCTs) comparing the use of hamstring tendon autograft with bone-patellar tendon-bone autograft for anterior cruciate ligament (ACL) reconstruction.

METHODS

The PubMed, Embase, and MEDLINE databases were queried for RCTs published since 2010 comparing autograft type (bone-patellar tendon-bone vs hamstring tendon) in ACL reconstruction surgery. The fragility index (FI) and reverse FI (rFI) were determined for significant and nonsignificant outcomes, respectively, as the number of outcome reversals required to change statistical significance. The fragility quotient (FQ) and reverse FQ, representing fragility as a proportion of the study population, were calculated by dividing the FI and rFI, respectively, by the sample size.

RESULTS

We identified 19 RCTs reporting 55 total dichotomous outcomes. The median FI of the 55 total outcomes was 5 (interquartile range [IQR], 4-7), meaning a median of 5 outcome event reversals would alter the outcomes' significance. Five outcomes were reported as statistically significant with a median FI of 4 (IQR, 2-6), meaning a median of 4 outcome event reversals would change outcomes to be nonsignificant. Fifty outcomes were reported as nonsignificant with a median rFI of 5 (IQR, 4-7), meaning a median of 5 outcome event reversals would change outcomes to be significant. The FQ and reverse FQ for significant and nonsignificant outcomes were 0.025 (IQR, 0.018-0.045) and 0.082 (IQR, 0.041-0.106), respectively. For 61.8% of outcomes, patients lost to follow-up exceeded the corresponding FI or rFI.

CONCLUSIONS

There is substantial statistical fragility in recent RCTs on autograft choice in ACL reconstruction surgery given that altering a few outcome events is sufficient to reverse study findings. For over half of outcomes, maintaining patients lost to follow-up may have been sufficient to reverse study conclusions.

CLINICAL RELEVANCE

We recommend co-reporting FIs and P values to provide a more comprehensive representation of a study's conclusions when conducting an RCT.

The canonical HPA axis facilitates and maintains light adaptive behavior

The vertebrate stress response (SR) is mediated by the hypothalamic-pituitary-adrenal (HPA) axis and contributes to generating context appropriate physiological and behavioral changes. Although the HPA axis plays vital roles both in stressful and basal conditions, research has focused on the response under stress. To understand broader roles of the HPA axis in a changing environment, we characterized an adaptive behavior of larval zebrafish during ambient illumination changes. The glucocorticoid receptor (nr3c1) was necessary to maintain basal locomotor activity in light and darkness. The HPA axis was required to adapt to light more efficiently but became dispensable when longer illumination was provided. Light adaptation was more efficient in dimmer light and did not require the mineralocorticoid receptor (nr3c2). Our findings show that the HPA axis contributes to the SR at various stages, facilitating the phasic response and maintaining an adapted basal state, and that certain adaptations occur without HPA axis activity.

Statistical Fragility of Randomized Controlled Trials Evaluating Platelet-Rich Plasma Use for Knee Osteoarthritis: A Systematic Review

Background

Numerous studies have been published on the use of platelet-rich plasma (PRP) for knee osteoarthritis (OA), with conflicting results.

Purpose

To determine the fragility index (FI) and fragility quotient (FQ) of randomized controlled trials (RCTs) that evaluated the use of PRP to treat knee OA.

Study Design

Systematic review.

Methods

RCTs evaluating the efficacy of PRP injections for knee OA from 2000 to 2020 were included for analysis according to PRISMA guidelines. The FI was determined by calculating the number of outcome event reversals required to change the statistical significance. The associated FQ was determined by dividing the FI by the sample size.

Results

Our initial search resulted in 41,149 studies, of which 8 RCTs (678 patients, 72 outcome events) were included in the analysis. One study failed to report PRP formulation details, whereas 87.5% of studies reported using either leukocyte-rich or leukocyte-poor PRP. The platelet concentration was reported in 25% of the included trials. The overall FI of the 72 outcome events was 8.5. Accounting for sample size, the associated FQ was determined to be 0.14, suggesting that the reversal of 14% of outcome events was required to change outcome significance. There were 51 statistically significant outcomes, of which the FI and FQ were 12 and 0.164, respectively.

Conclusion

Comprehensive fragility analysis suggested that the published literature evaluating the efficacy of PRP use for knee OA may lack statistical stability. We recommend the reporting of both an FI and FQ in addition to P value analysis to provide a clear and thorough understanding of the statistical integrity of studies reporting on PRP use for knee OA.

The Fragility of Tourniquet Use in Total Knee Arthroplasty: A Systematic Review of Randomized Controlled Trials

BACKGROUND

Physicians utilize P-values to interpret clinical trial data and guide patient-care decisions. Fragility analysis assesses the stability of statistical findings in relation to outcome event reversals. This study assessed the statistical fragility of recent randomized controlled trials (RCTs) investigating tourniquet use in total knee arthroplasty (TKA).

METHODS

We queried PubMed, EMBASE, and MEDLINE for RCTs comparing outcomes in TKA based on tourniquet use. Fragility index (FI) and reverse fragility index (reverse FI) were calculated - for significant and nonsignificant outcomes, respectively - as the number of outcome reversals required to change statistical significance. The fragility quotient (FQ) was calculated by dividing the FI or reverse FI by the sample size. Median overall FI and FQ were calculated for all included outcomes, and sub-analyses were performed by reported significance. The literature search yielded 23 studies reporting 91 total dichotomous outcomes.

RESULTS

Overall median FI was 4 with an interquartile range (IQR) of 3 to 6. Overall median FQ was 0.0476 (IQR 0.0291 to 0.0867). A total of 11 outcomes were statistically significant with a median FI and FQ of 2 (IQR 1.5 to 5) and 0.0200 (IQR 0.0148 to 0.0484), respectively. There were 80 outcomes that were nonsignificant with a median reverse FI of 4 (IQR 3 to 6). Loss to follow-up was greater than the median FI in 17.6% of outcomes.

CONCLUSION

Altering a small number of outcomes is often sufficient to reverse findings in RCTs evaluating tourniquet use in TKA. We recommend including fragility analyses to increase reliability in the interpretation of study conclusions.

Errors and complications in clinical periodontal practice due to methodologic bias and bad interpretation of the evidence

Different types of errors and complications may arise during and after the execution of periodontal or implant-related procedures. Some of the most relevant, although also controversial, and less commented, causative agents of errors and complications are methodological biases and bad interpretation of the evidence. Proper assessment of the literature requires of solid clinical knowledge combined with a systematic approach built on the recognition of common methodological biases and the avoidance of interpretive errors to critically retrieve, dissect, and judiciously apply available information for the promotion of periodontal and peri-implant health. This review addresses common types of methodological bias and interpretive errors that can alter the reader's perceptions on the real effect and potential ramifications of the reported outcomes of a given therapeutic approach due to bad interpretation of the available evidence: (1) types of methodological biases; (2) spin and interpretive bias; (3) interpretation pitfalls when assessing the evidence (4) choice of relevant endpoints to answer the question(s) of interest; and (5) balance between statistical significance and clinical relevance.

A Framework to Avoid Significance Fallacy

This manuscript presents a concise approach to tackle the widespread misuse of statistical significance in scientific research, focusing on public health. It offers practical guidance for conducting accurate statistical evaluations and promoting easily understandable results based on actual evidence. When conducting a statistical study to inform decision-making, it is recommended to follow a step-by-step sequence while considering various factors. Firstly, multiple target hypotheses should be adopted to assess the compatibility of experimental data with different models. Reporting all P-values in full, rounded in order to have a single non-zero significant digit, enhances transparency and reduces the likelihood of exaggerating the state of the evidence. Detailed documentation of the procedures used to evaluate the compatibility between test assumptions and data should be provided for rigorous assessment. A descriptive evaluation of results can be aided by using statistical compatibility ranges, which help avoid misrepresenting the evidence. Separately evaluating and reporting statistical compatibility and effect size prevents the magnitude fallacy. Additionally, reporting measures of statistical effect size enables evaluation of sectoral relevance, such as clinical significance. Multiple compatibility intervals, such as 99%, 95%, and 90% confidence intervals, should be reported to allow readers to assess the variation of P-values based on the width of the interval. These recommendations aim to enhance the robustness and interpretability of statistical analyses and promote transparent reporting of findings. The author encourages journal adoption of similar frameworks to enhance scientific rigor, particularly in the field of medical science.

A Social Network Analysis Approach to Evaluate the Relationship Between the Mobility Network Metrics and the COVID-19 Outbreak

The emergence of the new coronavirus in late 2019 further highlighted the human need for solutions to explore various aspects of deadly pandemics. Providing these solutions will enable humans to be more prepared for dealing with possible future pandemics. In addition, it helps governments implement strategies to tackle and control infectious diseases similar to COVID-19 faster than ever before. In this article, we used the social network analysis (SNA) method to identify high-risk areas of the new coronavirus in Iran. First, we developed the mobility network through the transfer of passengers (edges) between the provinces (nodes) of Iran and then evaluated the in-degree and page rank centralities of the network. Next, we developed 2 Poisson regression (PR) models to predict high-risk areas of the disease in different populations (moderator) using the mobility network centralities (independent variables) and the number of patients (dependent variable). The P-value of .001 for both prediction models confirmed a meaningful interaction between our variables. Besides, the PR models revealed that in higher populations, with the increase of network centralities, the number of patients increases at a higher rate than in lower populations, and vice versa. In conclusion, our method helps governments impose more restrictions on high-risk areas to handle the COVID-19 outbreak and provides a viable solution for accelerating operations against future pandemics similar to the coronavirus.

Randomized Controlled Trials in Pediatric Cardiology: A Power Struggle?

Sample size and statistical power are often limited in pediatric cardiology studies due to the relative infrequency of specific congenital malformations of the heart and specific circulatory physiologies. The primary aim of this study was to determine what proportion of pediatric cardiology randomized controlled trials achieve an 80% statistical power. Secondary aims included characterizing reporting habits in these studies. A systematic review was performed to identify pertinent pediatric cardiology randomized controlled trials. The following data were collected: publication year, journal, if "power" or "sample size" were mentioned if a discrete, primary endpoint was identified. Power analyses were conducted to assess if the sample size was adequate to demonstrate results at 80% power with a p-value of less than 0.05. A total of 83 pediatric cardiology randomized controlled trials were included. Of these studies, 48% mentioned "power" or "sample size" in the methods, 49% mentioned either in the results, 12% mentioned either in the discussion, and 66% mentioned either at any point in the manuscript. 63% defined a discrete, primary endpoint. 38 studies (45%) had an adequate sample size to demonstrate differences with 80% power at a p-value of less than 0.05. A majority of these are not powered to reach the conventionally accepted 80% power target. Adequately powered studies were found to be more likely to report "power" or "sample size" and have a discrete, primary endpoint.

The Fragility of Statistical Significance in Patellofemoral Instability Research: A Systematic Review

BACKGROUND

Fragility analysis is increasingly utilized to evaluate the robustness of results within the orthopaedic literature and has frequently revealed instability of reported outcomes.

PURPOSE/HYPOTHESIS

The purpose of this investigation was to utilize a fragility analysis to evaluate the stability of reported results in the patellofemoral instability (PFI) literature. We hypothesized the demonstration of significant fragility in patellofemoral research to be similar to that identified throughout other areas of the orthopaedic literature.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

The PubMed database was queried from January 1, 2000, to October 10, 2020 for comparative trials in 10 prominent orthopaedic journals that reported dichotomous outcomes related to the management of PFI. The fragility index (FI) and the fragility quotient (FQ) were calculated for each individual outcome event, and the overall FI and FQ were determined for all included studies.

RESULTS

A total of 22 comparative studies comprising 11 randomized controlled trials and 11 nonrandomized trials were included for the analysis. A total of 75 outcome events underwent a fragility analysis and revealed a median FI and FQ of 3 (interquartile range [IQR], 1-5) and 0.043 (IQR, 0.018-0.081), respectively. Also 27% of included studies reported loss to follow-up greater than the overall FI, therefore suggesting the maintenance of the follow-up may have resulted in the reversal of significance.

CONCLUSION

The result of the comprehensive fragility analysis demonstrated a lack of robustness in PFI research with the alteration of only a few outcome events required to reverse statistical significance. We therefore recommend the triple reporting of the P value, the FI, and the FQ to aid in the interpretation of the statistical integrity of future comparative trials in the PFI literature.

The Statistical Fragility of Operative vs Nonoperative Management for Achilles Tendon Rupture: A Systematic Review of Comparative Studies

BACKGROUND

The statistical significance of randomized controlled trials (RCTs) and comparative studies is often conveyed utilizing the P value. However, P values are an imperfect measure and may be vulnerable to a small number of outcome reversals to alter statistical significance. The interpretation of the statistical strength of these studies may be aided by the inclusion of a Fragility Index (FI) and Fragility Quotient (FQ). This study examines the statistical stability of studies comparing operative vs nonoperative management for Achilles tendon rupture.

METHODS

A systematic search was performed of 10 orthopaedic journals between 2000 and 2021 for comparative studies focusing on management of Achilles tendon rupture reporting dichotomous outcome measures. FI for each outcome was determined by the number of event reversals necessary to alter significance (P < .05). FQ was calculated by dividing the FI by the respective sample size. Additional subgroup analyses were performed.

RESULTS

Of 8020 studies screened, 1062 met initial search criteria with 17 comparative studies ultimately included for analysis, 10 of which were RCTs. A total of 40 outcomes were examined. Overall, the median FI was 2.5 (interquartile range [IQR] 2-4), the mean FI was 2.90 (±1.58), the median FQ was 0.032 (IQR 0.012-0.069), and the mean FQ was 0.049 (±0.062). The FI was less than the number of patients lost to follow-up for 78% of outcomes.

CONCLUSION

Studies examining the efficacy of operative vs nonoperative management of Achilles tendon rupture may not be as statistically stable as previously thought. The average number of outcome reversals needed to alter the significance of a given study was 2.90. Future analyses may benefit from the inclusion of a fragility index and a fragility quotient in their statistical analyses.

Frequentist and Bayesian Hypothesis Testing: An Intuitive Guide for Urologists and Clinicians

Given the limitations of frequentist method for null hypothesis significance testing, different authors recommend alternatives such as Bayesian inference. A poor understanding of both statistical frameworks is common among clinicians. The present is a gentle narrative review of the frequentist and Bayesian methods intended for physicians not familiar with mathematics. The frequentist p-value is the probability of finding a value equal to or higher than that observed in a study, assuming that the null hypothesis (H0) is true. The H0 is rejected or not based on a p threshold of 0.05, and this dichotomous approach does not express the probability that the alternative hypothesis (H1) is true. The Bayesian method calculates the probability of H1 and H0 considering prior odds and the Bayes factor (Bf). Prior odds are the researcher's belief about the probability of H1, and the Bf quantifies how consistent the data is concerning H1 and H0. The Bayesian prediction is not dichotomous but is expressed in continuous scales of the Bf and of the posterior odds. The JASP software enables the performance of both frequentist and Bayesian analyses in a friendly and intuitive way, and its application is displayed at the end of the paper. In conclusion, the frequentist method expresses how consistent the data is with H0 in terms of p-values, with no consideration of the probability of H1. The Bayesian model is a more comprehensive prediction because it quantifies in continuous scales the evidence for H1 versus H0 in terms of the Bf and the posterior odds.

Management of Landslides in a Rural–Urban Transition Zone Using Machine Learning Algorithms—A Case Study of a National Highway (NH-44), India, in the Rugged Himalayan Terrains

Landslides are critical natural disasters characterized by a downward movement of land masses. As one of the deadliest types of disasters worldwide, they have a high death toll every year and cause a large amount of economic damage. The transition between urban and rural areas is characterized by highways, which, in rugged Himalayan terrain, have to be constructed by cutting into the mountains, thereby destabilizing them and making them prone to landslides. This study was conducted landslide-prone regions of the entire Himalayan belt, i.e., National Highway NH-44 (the Jammu–Srinagar stretch). The main objectives of this study are to understand the causes behind the regular recurrence of the landslides in this region and propose a landslide early warning system (LEWS) based on the most suitable machine learning algorithms among the four selected, i.e., multiple linear regression, adaptive neuro-fuzzy inference system (ANFIS), random forest, and decision tree. It was found that ANFIS and random forest outperformed the other proposed methods with a substantial increase in overall accuracy. The LEWS model was developed using the land system parameters that govern landslide occurrence, such as rainfall, soil moisture, distance to the road and river, slope, land surface temperature (LST), and the built-up area (BUA) near the landslide site. The developed LEWS was validated using various statistical error assessment tools such as the root mean square error (RMSE), mean square error (MSE), confusion matrix, out-of-bag (OOB) error estimation, and area under the receiver operating characteristic (ROC) curve (AUC). The outcomes of this study can help to manage landslide hazards in the Himalayan urban–rural transition zones and serve as a sample study for similar mountainous regions of the world.

Statistical Fragility of Single-Row Versus Double-Row Anchoring for Rotator Cuff Repair: A Systematic Review of Comparative Studies

Background:

Comparative studies and randomized controlled trials (RCTs) often use the P (probability) value to convey the statistical significance of their findings. P values are an imperfect measure, however, and are vulnerable to a small number of outcome reversals to alter statistical significance. The inclusion of a fragility index (FI) and fragility quotient (FQ) may aid in the interpretation of a study’s statistical strength.

Purpose/Hypothesis:

The purpose of this study was to examine the statistical stability of studies comparing single-row to double-row rotator cuff repair. It was hypothesized that the findings of these studies would be vulnerable to a small number of outcome event reversals, often fewer than the number of patients lost to follow-up.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

We analyzed comparative studies and RCTs on primary single-row versus double-row rotator cuff repair that were published between 2000 and 2021 in 10 leading orthopaedic journals. Statistical significance was defined as a P < .05. The FI for each outcome was determined by the number of event reversals necessary to alter significance. The FQ was calculated by dividing the FI by the respective sample size.

Results:

Of 4896 studies screened, 22 comparative studies, 10 of which were RCTs, were ultimately included for analysis. A total of 74 outcomes were examined. Overall, the median FI was 2 (interquartile range [IQR], 1-3), and the median FQ was 0.035 (IQR, 0.020-0.057). The mean FI was 2.55 ± 1.29, and the mean FQ was 0.043 ± 0.027. In 64% of outcomes, the FI was less than the number of patients lost to follow-up.) Additionally, 81% of significant outcomes needed just a single outcome reversal to lose their significance.

Conclusion:

Over half of the studies currently used to guide clinical practice have a number of patients lost to follow-up greater than their FI. The results of these studies should be interpreted within the context of these limitations. Future analyses may benefit from the inclusion of the FI and the FQ in their statistical analyses.

When the p Value Doesn't Cut It: The Fragility Index Applied to Randomized Controlled Trials in Colorectal Surgery

BACKGROUND

The American Statistical Association, among others, has called for the use of statistical methods beyond p ≤ 0.05. The fragility index is a statistical metric defined as the minimum number of patients for whom if an event rather than a nonevent occurred, then the p value would increase to ≥0.05. Previous reviews have demonstrated that many randomized controlled trials have a low fragility index, suggesting they may not be robust.

OBJECTIVE

The purpose of this study was to review the fragility indices of randomized controlled trials in colorectal surgery.

DATA SOURCES

A PubMed search was performed.

STUDY SELECTION

Colorectal surgery randomized controlled trials with a dichotomous primary outcome p ≤ 0.05 and publication between 2016 and 2018 were systematically identified.

INTERVENTIONS

All procedural interventions related to colorectal surgery were included.

MAIN OUTCOME MEASURES

The main measures were the fragility index and the number of patients lost to follow-up for each trial. The percentage of trials with the number of patients lost to follow-up greater than the fragility index was calculated.

RESULTS

In total, 712 abstracts were reviewed, with 90 trials meeting the inclusion criteria. The median fragility index was 3 (interquartile range of 1 to 10). In 51 of the 90 trials (57%), the number of patients lost to follow-up was greater than the fragility index.

LIMITATIONS

The fragility index is only one measure of the robustness of a randomized clinical trial.

CONCLUSIONS

Most colorectal surgery randomized controlled trials have a low fragility index. In 57% of trials, more patients were lost to follow-up than would be required to change the outcome of the trial from "significant" to "nonsignificant" based on the p value. This emphasizes the importance of assessing the robustness of clinical trials when considering their clinical application, rather than relying solely on the p value. See Video Abstract at http://links.lww.com/DCR/B741.CUANDO EL VALOR-P ES INSUFICIENTE: ÍNDICE DE FRAGILIDAD APLICADO EN ESTUDIOS ALEATORIOS CONTROLADOS EN CIRUGÍA COLORECTAL.

ANTECEDENTES

La Sociedad Estadounidense de Estadística, entre otros, ha pedido el uso de métodos estadísticos más allá de p <0,05. El índice de fragilidad es una medida estadística definida como el número de desenlaces que podrían cambiar para revertir, o conseguir, la significación estadística, así el valor p aumentaría a ≥ 0,05. Las revisiones anteriores han demostrado que muchos estudios aleatorios controlados tienen un índice de fragilidad bajo, lo que sugiere que pueden poco sólidos.

OBJETIVO

El propósito de la présente investigación fué de revisar los índices de fragilidad de los estudios aleatorios controlados en cirugía colorrectal.

FUENTES DE DATOS

PubMed.

SELECCIN DE ESTUDIOS

Se identificaron sistemáticamente estudios aleatorios controlados de cirugía colorrectal con un resultado primario dicotómico, valor de p ≤ 0,05 y publicados entre 2016-2018.

INTERVENCIONES

Se incluyeron todas aquellas intervenciones con procedimientos relacionados con la cirugía colorrectal.

PRINCIPALES MEDIDAS DE RESULTADO

Las principales medidas fueron: el índice de fragilidad y el número de pacientes perdidos durante el seguimiento en cada estudio. Se calculó el el índice de fragilidad en porcentaje de estudios con el mayor número de pacientes perdidos durante el seguimiento mas prolongado.

RESULTADOS

En total, se revisaron 712 resúmenes con 90 ensayos que cumplieron con los criterios de inclusión. La mediana del índice de fragilidad fue de 3 (rango intercuartíl de 1 a 10). En 51 de los 90 estudios (57%), el número de pacientes perdidos durante el seguimiento fue mayor que el índice de fragilidad.

LIMITACIONES

El índice de fragilidad es solo una medida de la robustez de un estúdio clínico aleatorio.

CONCLUSIONES

La mayoría de los estudios aleatorios y controlados en cirugía colorrectal tienen un índice de fragilidad bajo. En el 57% de los estudios, se perdieron más pacientes durante el seguimiento de los que se necesitarían para cambiar el resultado del estudios de grado "significativo" a un grado "no significativo" según el valor-p. Este concepto enfatiza la importancia de evaluar la robustez de los estudios clínicos al considerar su aplicación verdadera aplicación clínica, en lugar de depender únicamente del valor-p. Consulte Video Resumen en http://links.lww.com/DCR/B741. (Traducción-Dr. Xavier Delgadillo).

The Statistical Fragility of Single-Bundle vs Double-Bundle Autografts for ACL Reconstruction: A Systematic Review of Comparative Studies

Background:

The statistical significance of a given study outcome can be liable to small changes in findings. P values are common, but imperfect statistical methods to convey significance, and inclusion of the fragility index (FI) and fragility quotient (FQ) may provide a clearer perception of statistical strength.

Purpose/Hypothesis:

The purpose was to examine the statistical stability of studies comparing primary single-bundle to double-bundle anterior cruciate ligament reconstruction (ACLR) utilizing autograft and independent tunnel drilling. It was hypothesized that the study findings would be vulnerable to a small number of outcome event reversals, often less than the number of patients lost to follow-up.

Study Design:

Systematic review; Level of evidence, 2.

Methods:

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the authors searched PubMed for comparative studies and randomized controlled trials (RCTs) published in select journals, based on impact factor, between 2005 and 2020. Risk-of-bias assessment and methodology scoring were conducted for the included studies. A total of 48 dichotomous outcome measures were examined for possible event reversals. The FI for each outcome was determined by the number of event reversals necessary to alter significance. The FQ was calculated by dividing the FI by the respective sample size.

Results:

Of the 1794 studies screened, 15 comparative studies were included for analysis; 13 studies were RCTs. Overall, the mean FI and FQ were 3.14 (IQR, 2-4) and 0.050 (IQR, 0.032-0.062), respectively. For 72.9% of outcomes, the FI was less than the number of patients lost to follow-up.

Conclusion:

Studies comparing single-bundle versus double-bundle ACLR may not be as statistically stable as previously thought. Comparative studies and RCTs are at substantial risk for statistical fragility, with few event reversals required to alter significance. The reversal of fewer than 4 outcome events in a treatment group can alter the statistical significance of a given result; this is commonly less than the number of patients lost to follow-up. Future comparative study analyses might consider including FI and FQ with P values in their statistical analysis.

Factors Influencing Consumer Purchase Intention of Luxury Branded Perfumes

The Prestige Cosmetics & Fragrances segment dominates the luxury consumer goods market, which has grown considerably over the past decade. According to the Coco Chanel quote, «Luxury is a necessity that begins where necessity ends». Luxurious goods were once considered a luxury reserved for a select few. «Luxury» was used to describe uncommon and limited-supply items which were only available to a select group of people. As time has progressed, luxury goods have become more accessible to middle-class consumers as the luxury market has grown. A total of more than 1.2 trillion euros was spent on the luxury market in 2018. Because of the increasing purchasing power of today’s consumers and the large size of the global luxury market, understanding this consumer group is critical to a company’s success in enhancing its business success in the luxury perfume market. Developing effective plans to meet and exceed consumer expectations is essential for companies in the luxury industry. A luxury brand has distinct characteristics that make it stand out from the rest. This study examined these and other theories focusing on five factors influencing consumers’ purchase intention of luxury branded perfumes. The five factors above are perceived uniqueness, brand image, quality, price, and status. This study aims to shed light on the factors influencing the desire to purchase high-end branded perfumes. More specifically, it aims to discover the root causes of the phenomenon of buying luxury branded perfumes and the primary determinants of luxury-goods consumption. A survey was used to gather data, and structural equation modeling with partial least squares was used to analyse the framework. Because of the findings, four variables (brand image, quality, price, and status) were found to have a positive relationship with purchase intention. The results also show that perceived uniqueness does not significantly impact the desire to purchase luxury perfumes. Marketers and managers could use the results of this study to understand luxury consumer behaviours better and develop marketing strategies that would help their products succeed in the luxury market.

A machine and human reader study on AI diagnosis model safety under attacks of adversarial images

While active efforts are advancing medical artificial intelligence (AI) model development and clinical translation, safety issues of the AI models emerge, but little research has been done. We perform a study to investigate the behaviors of an AI diagnosis model under adversarial images generated by Generative Adversarial Network (GAN) models and to evaluate the effects on human experts when visually identifying potential adversarial images. Our GAN model makes intentional modifications to the diagnosis-sensitive contents of mammogram images in deep learning-based computer-aided diagnosis (CAD) of breast cancer. In our experiments the adversarial samples fool the AI-CAD model to output a wrong diagnosis on 69.1% of the cases that are initially correctly classified by the AI-CAD model. Five breast imaging radiologists visually identify 29%-71% of the adversarial samples. Our study suggests an imperative need for continuing research on medical AI model's safety issues and for developing potential defensive solutions against adversarial attacks.

Climate Finance: Mapping Air Pollution and Finance Market in Time Series

Climate finance is growing popular in addressing challenges of climate change because it controls the funding and resources to emission entities and promotes green manufacturing. In this study, we determined that PM2.5, PM10, SO2, NO2, CO, and O3 are the target pollutant in the atmosphere and we use a deep neural network to enhance the regression analysis in order to investigate the relationship between air pollution and stock prices of the targeted manufacturer. We also conduct time series analysis based on air pollution and heavy industry manufacturing in China, as the country is facing serious air pollution problems. Our study uses Convolutional-Long Short Term Memory in 2 Dimension (ConvLSTM2D) to extract the features from air pollution and enhance the time series regression in the financial market. The main contribution in our paper is discovering a feature term that impacts the stock price in the financial market, particularly for the companies that are highly impacted by the local environment. We offer a higher accurate model than the traditional time series in the stock price prediction by considering the environmental factor. The experimental results suggest that there is a negative linear relationship between air pollution and the stock market, which demonstrates that air pollution has a negative effect on the financial market. It promotes the manufacturer’s improving their emission recycling and encourages them to invest in green manufacture—otherwise, the drop in stock price will impact the company funding process.

Comparative Studies in the Shoulder Literature Lack Statistical Robustness: A Fragility Analysis

Purpose

Evidenced-based decision-making is rooted in comparative clinical studies; however, a small number of outcome event reversals have the potential to change study significance. The purpose of this study was to determine the utility of applying fragility analysis to comparative studies in the published orthopaedic shoulder literature.

Methods

Comparative clinical shoulder research studies reporting 1:1 dichotomous categorical data were analyzed in 6 leading orthopaedic journals between 2006 and 2016. Statistical significance was defined as a P value of less than .05. The fragility index (FI) for each study outcome was determined by the number of event reversals required to change the P value to either greater or less than 0.05, thus changing the study conclusions. The associated fragility quotient (FQ) was determined by dividing the FI by the total population comprising a particular outcome.

Results

Of the 23,897 studies screened, 3,591 met search criteria, with 198 comparative studies ultimately included for analysis, 67 of which were randomized controlled trials. There were 357 total outcome events with 74 reported as significant and 283 as not significant. The FI was 4 (IQR 2-6) with an associated FQ of 0.066 (interquartile range [IQR] 0.038-0.102). There was no difference in statistical fragility between randomized and nonrandomized trials with both revealing a FI of 4 and FQ of 0.068 (IQR 0.044-0.107) and 0.065 (IQR 0.031-0.101), respectively.

Conclusions

This current analysis reveals that comparative shoulder studies published in six leading orthopaedic journals are at risk of statistical fragility. As such, contemporary clinical shoulder literature may not be as robust as traditionally perceived with the reversal of only a few outcome events required to change study significance. Therefore, we advocate the reporting of both FI and FQ in addition to the P value as statistical complements to all comparative investigations to provide a more comprehensive understanding of trial stability and significance in the published shoulder literature.

Clinical Relevance

Comparative study designs are commonly employed in shoulder research. Several studies in both the general medical and orthopaedic literature have identified a lack of statistical robustness through comprehensive fragility analysis. Our findings demonstrate the P value may be an inadequate independent statistical metric requiring the complement of a FI and FQ to aid in the interpretation and understanding of study significance for clinical decision-making.

The Statistical Fragility of Platelet-Rich Plasma in Rotator Cuff Surgery: A Systematic Review and Meta-analysis

BACKGROUND

The practice of evidence-based medicine relies on objective data to guide clinical decision-making with specific statistical thresholds conveying study significance.

PURPOSE

To determine the utility of applying the fragility index (FI) and the fragility quotient (FQ) analysis to randomized controlled trials (RCTs) evaluating the utilization of platelet-rich plasma (PRP) in rotator cuff repairs (RCRs).

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

RCTs pertaining to the utilization of PRP in surgical RCRs published in 13 peer-reviewed journals from 2000 to 2020 were evaluated. The FI was determined by manipulating each reported outcome event until a reversal of significance was appreciated. The associated FQ was determined by dividing the FI by the sample size.

RESULTS

Of the 9746 studies screened, 19 RCTs were ultimately included for analysis. The overall FI incorporating all 19 RCTs was only 4, suggesting that the reversal of only 4 events is required to change study significance. The associated FQ was determined as 0.092. Of the 43 outcome events reporting lost to follow-up data, 13 (30.2%) represented lost to follow-up >4.

CONCLUSION

Our analysis suggests that RCTs evaluating PRP for surgical RCRs may lack statistical stability with only a few outcome events required to alter trial significance. Therefore, we recommend the reporting of an FI and an FQ in conjunction with P value analysis to carefully interpret the integrity of statistical stability in future comparative trials.

CLINICAL RELEVANCE

Clinical decisions are often informed by statistically significant results. Thus, a true understanding of the robustness of the statistical findings informing clinical decision-making is of critical importance.

The Fragility of Statistical Findings in Achilles Tendon Injury Research: A Systematic Review

Probability analysis with the reporting of P values is often used to determine the statistical significance of study findings in the Achilles literature. The purpose of this study was to determine the utility of applying a fragility analysis to comparative trials evaluating Achilles tendon injuries.

The Statistical Fragility of Hamstring Versus Patellar Tendon Autografts for Anterior Cruciate Ligament Reconstruction: A Systematic Review of Comparative Studies

BACKGROUND

Evidence-based medicine utilizes data to inform clinical decision making, despite the ability of a small number of outcome reversals to change statistical significance. P values are common measurements of statistical significance that possess inherent flaws. The inclusion of the fragility index (FI) and fragility quotient (FQ) may provide a clearer conveyance of statistical strength.

PURPOSE/HYPOTHESIS

The purpose was to examine the statistical stability of studies comparing hamstring tendon and bone-patellar tendon-bone autografts in primary single-bundle anterior cruciate ligament reconstruction with independent tunnel drilling. We hypothesized that the findings of these studies are vulnerable to a small number of outcome event reversals, often fewer than the number of patients lost to follow-up.

STUDY DESIGN

Systematic review.

METHODS

Comparative studies and randomized controlled trials (RCTs) published in 10 leading orthopaedic journals between 2000 and 2020 were analyzed. Statistical significance was defined as a P value ≤.05. FI for each outcome was determined by the number of event reversals necessary to alter significance. FQ was calculated by dividing the FI by the respective sample size.

RESULTS

Of the 1803 studies screened, 643 met initial search criteria, with 18 comparative studies ultimately included for analysis, 8 of which were RCTs. A total of 114 outcomes were examined. Overall, the mean (interquartile range) FI and FQ were 3.77 (2-4) and 0.040 (0.016-0.055), respectively. The FI was less than the number of patients lost to follow-up for 76.3% of outcomes.

CONCLUSION

Studies examining graft choice for anterior cruciate ligament reconstruction may not be as statistically stable as previously thought. Comparative studies and RCTs are at substantial risk for statistical fragility, with few event reversals required to alter significance. The reversal of <4 outcome events in a treatment group can alter the statistical significance of a given result; this is commonly fewer than the number of patients lost to follow-up. Future comparative study analyses might consider including FI and FQ with P values in their statistical analysis.

Betahydroxybutyrate Consumption in Autopsy Brain Tissue from Alzheimer's Disease Subjects

Background:

Alzheimer’s disease (AD) features perturbed brain glucose utilization, which could contribute to brain bioenergetic failure. This led some to consider using ketone bodies to enhance AD brain bioenergetics and treat AD.

Objective:

We evaluated the rate at which brain homogenates from persons with Alzheimer’s disease (AD) metabolize D-β-hydroxybutyrate (BHB).

Methods:

We homogenized pieces of temporal cortex from frozen autopsy brains obtained from recently deceased AD subjects (n = 4), and age-matched subjects that did not have clinical AD (n = 3). Measuring the rate of CO2 production that followed the introduction of radiolabeled BHB to the homogenates yielded a BHB utilization rate.

Results:

Compared to the control homogenates, the BHB-supported CO2 production rate was 66%lower in the AD homogenates (p < 0.05).

Conclusions:

AD brains can utilize BHB, albeit less robustly than control brains. In conjunction with a previous study that demonstrated reduced glucose utilization in AD brain homogenates, our BHB data provide further evidence of AD brain mitochondrial dysfunction or altered mitochondrial biology.

Data-Driven Models for Objective Grading Improvement of Parkinson's Disease

Parkinson's disease (PD) is a progressive disorder of the central nervous system that causes motor dysfunctions in affected patients. Objective assessment of symptoms can support neurologists in fine evaluations, improving patients' quality of care. Herein, this study aimed to develop data-driven models based on regression algorithms to investigate the potential of kinematic features to predict PD severity levels. Sixty-four patients with PD (PwPD) and 50 healthy subjects of control (HC) were asked to perform 13 motor tasks from the MDS-UPDRS III while wearing wearable inertial sensors. Simultaneously, the clinician provided the evaluation of the tasks based on the MDS-UPDRS scores. One hundred-ninety kinematic features were extracted from the inertial motor data. Data processing and statistical analysis identified a set of parameters able to distinguish between HC and PwPD. Then, multiple feature selection methods allowed selecting the best subset of parameters for obtaining the greatest accuracy when used as input for several predicting regression algorithms. The maximum correlation coefficient, equal to 0.814, was obtained with the adaptive neuro-fuzzy inference system (ANFIS). Therefore, this predictive model could be useful as a decision support system for a reliable objective assessment of PD severity levels based on motion performance, improving patients monitoring over time.

Influence of façade orientation on the leaching of biocides from building façades covered with mortars and plasters

Biocides used in building façades to prevent potential growth of algae, fungi and bacteria are of major concern regarding the quality of stormwater runoff. The aim of the study was to analyze the influence of the façade orientation on the biocide release under real weather conditions to gain information for the development of on-site treatment systems. Field tests with model houses containing two different plaster compositions were carried out over a period of 18 months. The results of the analyzed rain events demonstrate that façade orientation plays an important role in the leaching loads of biocides. Biocide loads in the runoff decreased corresponding to the wind direction. High cumulated active substance discharges of diuron (149 mg/m²), carbendazim (43.5 mg/m²), terbutryn (9.3 mg/m²) and octylisothiazolinone (OIT) (31.9 mg/m²) were found in the runoff of the façades facing the predominant weather orientation. Meanwhile, the highest concentrations of diuron (2.8 mg/L) and OIT (0.7 mg/L) were observed in the runoff from façades with smaller runoff volumes. The obtained results demonstrate that treatment facilities have to be installed at all building sides. The hydraulic and the substance load is highest at the weather side, which has a strong influence on the dimension and the lifetime of the treatment system.

Association of genetic variations in phosphatase and tensin homolog (PTEN) gene with polycystic ovary syndrome in South Indian women: a case control study

PURPOSE

The purpose of the study was to investigate the association between gene phosphate and tensin homolog (PTEN) single nucleotide polymorphisms (SNPs) and risk of developing polycystic ovary syndrome (PCOS) in South Indian women. PTEN is one of the most important tumor suppressor genes that regulate cell proliferation, migration, and death. It is also involved in the maintenance of genome stability. PCOS is one of the most common endocrine disorders among women of reproductive age. It is a heterogeneous syndrome characterized by abnormal reproductive cycles, irregular ovulation, hormonal imbalance, hyperandrogenism, acne and hirsutism.

RESEARCH QUESTION

What is the association status of PTEN SNPs with PCOS?

METHODS

A total of 240 subjects were recruited in this case-control study comprising 110 patients with PCOS and 130 individuals without PCOS. All the subjects were of South Indian origin. The genotyping of PTEN SNPs (rs1903858 A/G, rs185262832G/A and rs10490920T/C) was carried out on DNA from subjects by polymerase chain reaction (PCR) and sequencing analysis. Haplotype frequencies for multiple loci and the standardized disequilibrium coefficient (D') for pairwise linkage disequilibrium (LD) were surveyed by Haploview Software.

RESULTS

Our results showed significant increase in the frequencies of rs1903858 A/G (P = 0.0016), rs185262832 G/A (P = 0.0122) and rs10490920 T/C (P = 0.0234) genotypes and alleles in cases compared to controls.

CONCLUSION

The PTEN (rs1903858A/G, rs185262832G/A and rs10490920T/C) gene polymorphisms may constitute an inheritable risk factor for PCOS in South Indian women.

Preclinical studies on metal based anticancer drugs as enabled by integrated metallomics and metabolomics

Resistance development is a major obstacle for platinum-based chemotherapy, with the anticancer drug oxaliplatin being no exception. Acquired resistance is often associated with altered drug accumulation. In this work we introduce a novel -omics workflow enabling the parallel study of platinum drug uptake and its distribution between nucleus/protein and small molecule fraction along with metabolic changes after different treatment time points. This integrated metallomics/metabolomics approach is facilitated by a tailored sample preparation workflow suitable for preclinical studies on adherent cancer cell models. Inductively coupled plasma mass spectrometry monitors the platinum drug, while the metabolomics tool-set is provided by hydrophilic interaction liquid chromatography combined with high-resolution Orbitrap mass spectrometry. The implemented method covers biochemical key pathways of cancer cell metabolism as shown by a panel of >130 metabolite standards. Furthermore, the addition of yeast-based 13C-enriched internal standards upon extraction enabled a novel targeted/untargeted analysis strategy. In this study we used our method to compare an oxaliplatin sensitive human colon cancer cell line (HCT116) and its corresponding resistant model. In the acquired oxaliplatin resistant cells distinct differences in oxaliplatin accumulation correlated with differences in metabolomic rearrangements. Using this multi-omics approach for platinum-treated samples facilitates the generation of novel hypotheses regarding the susceptibility and resistance towards oxaliplatin.

HIV and sexually transmitted infection knowledge among women who have sex with women in four Southern African countries

Women who have sex with women in Southern Africa, where HIV prevalence is high, are often presumed to have minimal risk for sexually transmitted infections (STI) and HIV despite research documenting female-to-female transmission. This study examined the demographic and social factors contributing to female-to-female STI/HIV transmission knowledge among Southern African women who have sex with women using an integrated model of health literacy. In collaboration with community-based organisations in Botswana, Namibia, South Africa and Zimbabwe, data were collected through anonymous surveys (N = 591). Multivariable stepwise forward logistic regression assessed independent associations between participant characteristics and high vs. low knowledge using five items. Overall, 64.4% (n = 362) of women had high knowledge; 35.6% (n = 200) had low knowledge. Higher education (adjusted odds ratio [aOR]: 2.24, 95% confidence interval [CI]: 1.48, 3.40), regular income (aOR: 2.14, 95% CI: 1.43, 3.21), residence in Botswana (aOR: 3.12, 95% CI: 1.15, 8.48) and having ever received tailored STI/HIV information (aOR: 2.17, 95% CI: 1.41, 3.32) predicted significantly higher odds of high knowledge in the final multivariable model. Results suggest opportunities for peer-led sexual health programming and expanded HIV prevention campaigns addressing women who have sex with women.

Hypothesis Testing in Superiority, Noninferiority, and Equivalence Clinical Trials: Implications in Physical Medicine and Rehabilitation

In medical research, it is important to be able to examine whether there is a significant difference between two samples. With this, establishing an appropriate hypothesis is a critical, basic step for correct interpretation of results in inferential statistical data analysis. It is important to note that the aim of hypothesis testing is not to "accept" or "reject" the null hypothesis but to gauge the likelihood that the observed difference is genuine if the null hypothesis is true.Traditionally, the null hypothesis assumes that there is no statistically significant difference between the two groups. It has become more difficult to develop new treatments that are better than the standard of care. This review article summarizes and explains the methodology of the different types of clinical trials regarding the relevant basic statistical concepts and hypothesis testing.

Validity and reliability of the GYKO inertial sensor system for the assessment of the elbow range of motion

BACKGROUND

The evaluation of joints range of motion (ROM) represents a fundamental step in the diagnosis of joint disorders. Assessors usually measure the ROM angle through a universal goniometer (UG). GYKO inertial system (Microgate, Bolzano, Italy) represent a noninvasive, easy-to-use, Inertial Measurement Unit (IMU) method for the measurement of the elbow ROM. The aim of this study was to validate the GYKO digital device comparing it with the gold standard UG in the measurement of elbow flexion-extension ROM in healthy subjects.

METHODS

Thirty healthy subjects (15 females, 15 males; mean age: 34 years, range 25-58 years) were enrolled. The elbow ROM of the dominant arm was measured with two methods, UG and GYKO. Active flexion-extension movement of the elbow was measured by two operators with UG (A1_UG; A2_UG) and with GYKO (A1_GYKO; A2_GYKO; B_GYKO). Intra-rater reliability, inter-rater reliability, and concurrent validity were analyzed by intraclass correlation coefficient (ICC) values. Bland-Altman plot was used to compare UG and GYKO.

RESULTS

Both methods were very reliable (P<0.001). Intra-rater reliability showed strong correlation respectively for the UG (ICC=0.798) and for GYKO (ICC=0.859) while inter-rater reliability showed moderate correlation with UG (ICC=0.726) and strong correlation with GYKO (ICC=0.942). The concurrent validity, obtained by three comparisons (A1, A2 and B) showed moderate correlation (ICC: 0.576-0.776).

CONCLUSIONS

The results of this study support the use of GYKO as useful as the UG for the assessment of the active flexion-extension ROM of the elbow.

Development of an optimized febuxostat self-nanoemulsified loaded transdermal film: in-vitro, ex-vivo and in-vivo evaluation

Febuxostat (FBX) is used to treat gout and chronic hyperuricemia. However, its bioavailability is moderate (49%) as a result of low solubility and first-pass metabolism. Therefore, the aim of our study is to improve FBX bioavailability by enhancement its solubility using self-nanoemulsifying drug delivery system (SNEDDS) technique in the form of transdermal film to avoid hepatic metabolism. To accomplish this goal, Eight SNEDDS formulae were prepared according to a three-factor, two-level D-Optimal mixture design to evaluate the effect of different ratios of the Lemon oil (X1), the surfactant Tween-20 (X2), and the co-surfactant PEG-400 (X3) on the globule size in order to reach smallest globular size. Results revealed that SNEDDS globule size ranged from 177 to 454 nm. The optimized formula consisted of 20% oil, 40% surfactant and 40% co-surfactant. Diffusion study showed improved enhancement in skin permeation that was confirmed by imaging using fluorescence microscope. In vivo plasma data showed significant (p < 0.05) difference in FBX plasma levels and pharmacokinetic parameters when compared with raw FBX loaded film. In conclusion, FBX-SNEDDS loaded transdermal film could be a successful way to improve solubility and skin permeability that would lead to improvement in patient's compliance.

Most recommended medical interventions reach P < 0.005 for their primary outcomes in meta-analyses

Background

It has been proposed that the threshold of statistical significance should shift from P-value &lt; 0.05 to P-value &lt; 0.005, but there is concern that this move may dismiss effective, useful interventions. We aimed to assess how often medical interventions are recommended although their evidence in meta-analyses of randomized trials lies between P-value = 0.05 and P-value = 0.005.

Methods

We included Cochrane systematic reviews (SRs) published from 1 January 2013 to 30 June 2014 that had at least one meta-analysis with GRADE (Grading of Recommendations Assessment, Development and Evaluation) assessment and at least one primary outcome having favourable results for efficacy at P-value &lt; 0.05. Only comparisons of randomized trials between active versus no treatment/placebo were included. We then assessed the respective UpToDate recommendations for clinical practice from 22 May 2018 to 5 October 2018 and recorded how many treatments were recommended and what were the P-values in their meta-analysis evidence. The primary analysis was based on the first-listed outcomes.

Results

Of 608 screened SRs with GRADE assessment, 113 SRs were eligible, including 143 comparisons of which 128 comparisons had first-listed primary outcomes with UpToDate coverage. Altogether, 60% (58/97) of interventions with P-values &lt; 0.005 for their evidence were recommended versus 32% (10/31) of those with P-value 0.005–0.05. Therefore, most (58/68, 85.2%) of the recommended interventions had P-values &lt; 0.005 for the first-listed primary outcome. Of the 10 exceptions, 4 had other primary outcomes with P-values &lt; 0.005 and another 4 had additional extensive evidence for similar indications that would allow extrapolation for practice recommendations.

Conclusions

Few interventions are recommended without their evidence from meta-analyses of randomized trials reaching P-value &lt; 0.005.

P-Value Demystified

Biomedical research relies on proving (or disproving) a research hypothesis, and P value becomes a cornerstone of "null hypothesis significance testing." P value is the maximum probability of getting the observed outcome by chance. For a statistical test to achieve significance, the error by chance must be less than 5%. The pros are the P value that gives the strength of evidence against the null hypothesis. We can reject a null hypothesis depending on a small P value. However, the value of P is a function of sample size. When the sample size is large, the P value is destined to be small or "significant." P value is condemned by one school of thought who claims that focusing more on P value undermines the generalizability and reproducibility of research. For such a situation, presently, the scientific world is inclined in knowing the effect size, confidence interval, and the descriptive statistics; thus, researchers need to highlight them along with the P value. In spite of all the criticism, it needs to be understood that P value carries paramount importance in "precise" understanding of the estimation of the difference calculated by "null hypothesis significance testing." Choosing the correct test for assessing the significance of the difference is profoundly important. The choice can be arrived by asking oneself three questions, namely, the type of data, whether the data is paired or not, and on the number of study groups (two or more). It is worth mentioning that association between variables, agreement between assessments, time-trend cannot be arrived by calculating the P value alone but needs to highlight the correlation and regression coefficients, odds ratio, relative risk, etc.

Understanding Statistical Hypothesis Testing: The Logic of Statistical Inference

Statistical hypothesis testing is among the most misunderstood quantitative analysis methods from data science. Despite its seeming simplicity, it has complex interdependencies between its procedural components. In this paper, we discuss the underlying logic behind statistical hypothesis testing, the formal meaning of its components and their connections. Our presentation is applicable to all statistical hypothesis tests as generic backbone and, hence, useful across all application domains in data science and artificial intelligence.

Objective and automatic classification of Parkinson disease with Leap Motion controller

Background

The main objective of this paper is to develop and test the ability of the Leap Motion controller (LMC) to assess the motor dysfunction in patients with Parkinson disease (PwPD) based on the MDS-UPDRSIII exercises. Four exercises (thumb forefinger tapping, hand opening/closing, pronation/supination, postural tremor) were used to evaluate the characteristics described in MDS-UPDRSIII. Clinical ratings according to the MDS/UPDRS-section III items were used as target. For that purpose, 16 participants with PD and 12 healthy people were recruited in Ospedale Cisanello, Pisa, Italy. The participants performed standardized hand movements with camera-based marker. Time and frequency domain features related to velocity, angle, amplitude, and frequency were derived from the LMC data.

Results

Different machine learning techniques were used to classify the PD and healthy subjects by comparing the subjective scale given by neurologists against the predicted diagnosis from the machine learning classifiers. Feature selection methods were used to choose the most significant features. Logistic regression (LR), naive Bayes (NB), and support vector machine (SVM) were trained with tenfold cross validation with selected features. The maximum obtained classification accuracy with LR was 70.37%; the average area under the ROC curve (AUC) was 0.831. The obtained classification accuracy with NB was 81.4%, with AUC of 0.811. The obtained classification accuracy with SVM was 74.07%, with AUC of 0.675.

Conclusions

Results revealed that the system did not return clinically meaningful data for measuring postural tremor in PwPD. In addition, it showed limited potential to measure the forearm pronation/supination. In contrast, for finger tapping and hand opening/closing, the derived parameters showed statistical and clinical significance. Future studies should continue to validate the LMC as updated versions of the software are developed. The obtained results support the fact that most of the set of selected features contributed significantly to classify the PwPD and healthy subjects.

P in the right place: Revisiting the evidential value of P-values

P-values are often calculated when testing hypotheses in quantitative settings, and low P-values are typically used as evidential measures to support research findings in published medical research. This article reviews old and new arguments questioning the evidential value of P-values. Critiques of the P-value include that it is confounded, fickle, and overestimates the evidence against the null. P-values may turn out falsely low in studies due to random or systematic errors. Even correctly low P-values do not logically provide support to any hypothesis. Recent studies show low replication rates of significant findings, questioning the dependability of published low P-values. P-values are poor indicators in support of scientific propositions. P-values must be inferred by a thorough understanding of the study's question, design, and conduct. Null hypothesis significance testing will likely remain an important method in quantitative analysis but may be complemented with other statistical techniques that more straightforwardly address the size and precision of an effect or the plausibility that a hypothesis is true.

Decreased waterborne pathogenic bacteria in an urban aquifer related to intense shallow geothermal exploitation

The implications of intensive use of shallow geothermal energy resources in shallow urban aquifers are still not known for waterborne pathogens relevant to human health. Firstly, we hypothesized that waterborne enteric pathogens would be relatively increased in heated groundwater plumes. To prove this, microbiological sampling of 31 piezometers covering the domain of an urban groundwater body affected by microbiological contamination and energetically exploited by 70 groundwater heat pump systems was performed. Mean differences of pathogenic bacteria contents between impacted and non-impacted monitoring points were assessed with a two-tailed independent Student's t-test or Mann-Whitney U and correlation coefficients were also calculated. Surprisingly, the results obtained revealed a significant and generalized decrease in waterborne pathogen contents in thermally impacted piezometers compared to that of non-impacted piezometers. This decrease is hypothesized to be caused by a heat shock to bacteria within the heat exchangers. The statistically significant negative correlations obtained between waterborne pathogen counts and temperature could be explained by the spatial distribution of the bacteria, finding that bacteria start to recover with increasing distance from the injection point. Also, different behavior groups fitting exponential regression models were found for the bacteria species studied, justified by the different presence and influence of several aquifer parameters and major, minor and trace elements studied, as well as the coexistence with other bacteria species. The results obtained from this work reinforce the concept of shallow geothermal resources as a clean energy source, as they could also provide the basis to control the pathogenic bacteria contents in groundwater bodies.

Influence of tumour suppressor gene (TP53, BRCA1 and BRCA2) polymorphisms on polycystic ovary syndrome in South Indian women

OBJECTIVE

Polycystic Ovary Syndrome (PCOS) is a heterogeneous multifactorial endocrine metabolic disorder. In addition to hyperandrogenism, acne, hirsutism, obesity, oligoanovulation and infertility, insulin resistance is also a common feature in women of PCOS. Tumor suppressor genes (TSGs) perform essential function in the maintenance of genomic stability and regulatory pathways influencing the activity of several replication and transcription factors. The main aim of this study was to investigate the association of Single Nucleotide Polymorphisms of TP53, BRCA1and BRCA2 genes with the susceptibility to PCOS in South Indian women.

STUDY DESIGN

Present study investigated association between TP53 gene (rs1042522 G/C), BRCA1 (rs71361504 -/GTT, rs3092986 T/C) and BRCA2 (rs206118 A/G) and, SNPs and PCOS risk. Genotyping of TSGs was carried out on DNA from PCOS patients (n = 110) and controls (n = 130) of South Indian origin by polymerase chain reaction (PCR) and confirmed by sequencing analysis. The genotype frequency and allele distributions of cases and controls were analyzed using Fisher's exact test. Haplotype frequencies for multiple loci and the standardized disequilibrium coefficient (D') for pair wise linkage disequilibrium (LD) were assessed by Haploview Software.

RESULTS

Significant increase in frequencies ofTP53 (rs1042522 G/C), BRCA1 (rs71361504 -/GTT, rs3092986 T/C) genotypes and alleles in patients compared to controls. In addition, the frequency of the C/T (P = 0.002) and A/C (P = 0.012) haplotype was also significantly elevated in patients. But BRCA2 (rs206118 A/G) did not show significant association with PCOS.

CONCLUSION

The TP53 and BRCA1 may constitute an inheritable risk factor for PCOS in South Indian women.

A randomized controlled trial of a 12-week intensive lifestyle intervention program at a primary care obesity clinic for adults in western Saudi Arabia

Objectives:

To assess the ability of a 12-week primary care-based intensive lifestyle intervention (ILI), to facilitate a 5% reduction in baseline weight compared with an education-only active comparator (AC).

Methods:

A randomized clinical trial was conducted in a primary health care setting in Jeddah, Saudi Arabia between December 2014 and June 2015. Arab participants with obesity, but who were otherwise healthy (n=140), were randomized to the ILI (n=70) or AC (n=70) group. The ILI group received 8 clinical visits throughout the study. The AC group received only an initial health education session. The primary outcome was the proportion of participants who achieved clinically significant weight loss (≥5% of their baseline weight).

Results:

Participants in the ILI group were significantly more likely than those in the AC group to achieve the primary outcome (p=0.008, relative risk: 1.8 [95% confidence interval [CI]: 1.15 to 2.93). At week 12, the ILI group exhibited a mean weight decrease of 5.58 ± 5.60 kg (-5.37 ± 5.31%), significantly greater than that observed in the AC group (-2.8 ± 4.96 kg, -2.62 ± 4.34%, p=0.002), and corresponding to a weight loss advantage of 2.77 kg (95% CI: 1.01 to 4.54 kg) or 2.75% (95% CI: 1.13% to 4.37%).

Conclusion:

The 12-week primary care-based ILI program was effective in achieving a clinically meaningful weight reduction (≥5%) among Saudi and Arab patients with obesity.

Error measurement in craniometrics: The comparative performance of four popular assessment methods using 2000 simulated cranial length datasets (g-op)

For measurements to be accurate and precise, measurement errors should be small. In the anthropometry and craniofacial identification literature, four methods are commonly used for assessing measurement error: Pearson's product moment correlation coefficient (r), intra-class correlation coefficients (ICC), statistical significance tests (often reported by P-values) and the technical error of measurement (TEM; also known as Dalberg's error/ratio). In this paper, the performance of all four of these statistics were evaluated using maximum cranial lengths (g-op) from Howells (n=2524), by duplicating the dataset and mathematically adding known degrees of error to the second set. This was repeated under a broad array of trials (2000 total) each with slightly different amounts of error simulation to comprehensively assess the four error metrics in terms of descriptive power and utility, using the same data for each of the four error assessment methods. Data simulations included the addition of random and systematic errors of different sizes with absolute differences ranging from 1 to 50mm (or in relative terms, 28% of the original measurement). Two sample sizes (n=25 and 2524 individuals) were explored and all analyses were conducted in R. P-values from Student's t-tests only showed significant differences (P<0.05) for the larger sample size when the error was systematic. Small samples, and/or any with random error, did not yield low or significant P-values (P<0.05). When raw differences were <4mm for 95% of the sample (n=2524), the ICC and r were high (>0.97) and remained so even after tripling the error, such that 95% of the sample possessed raw differences up to 12mm (r=0.8). In contrast, the TEM was low initially (<2mm or r-TEM<1%), and then increased (<4.5mm and 2.5%, TEM and r-TEM respectively). These data show that P-values, ICC and r values hold substantial limits for error description as they do not always flag error well. In contrast, TEM appears to covary with error more saliently and holds the advantage that changes are reported in the units of the original measurement. For these reasons, TEM is recommended in favour to P-values, ICC and r.

Human Hand Motion Analysis during Different Eating Activities

The focus of this research is to analyse both human hand motion and force, during eating, with respect to differing food characteristics and cutlery (including a fork and a spoon). A glove consisting of bend and force sensors has been used to capture the motion and contact force exerted by fingers during different eating activities. The Pearson correlation coefficient has been used to show that a significant linear relationship exists between the bending motion of the fingers and the forces exerted during eating. Analysis of variance (ANOVA) and independent samples t-tests are performed to establish whether the motion and force exerted by the fingers while eating is influenced by the different food characteristics and cutlery. The middle finger motion showed the least positive correlation with index fingertip and thumb-tip force, irrespective of the food characteristics and cutlery used. The ANOVA and t-test results revealed that bending motion of the index finger and thumb varies with respect to differing food characteristics and the type of cutlery used (fork/spoon), whereas the bending motion of the middle finger remains unaffected. Additionally, the contact forces exerted by the thumb tip and index fingertip remain unaffected with respect to differing food types and cutlery used.