scholarly journals Statistical cures and other fallacies

2012 ◽  
Vol 18 (4) ◽  
pp. 387-390 ◽  
Author(s):  
Gary R Cutter
Keyword(s):  
Wishful Thinking ◽  
Percentage Change ◽  
Regression To The Mean ◽  
The Common ◽  
The Mean ◽  
Regression Towards The Mean ◽  
The Impact ◽  
Relapse Rates ◽  
Over Time

Relapse rates and thus the impact of therapies have been decreasing. Why they decline and the impact on our ability to understand which treatments are better require more than simple math. The objective of this review is to discuss the impact of regression to the mean, changes in outcome effects and how we compare outcomes over time and among studies. This paper provides discourse on the topics of regression to the mean, some examples of the pitfalls of changes and some difficulties in the interpretation of the common percentage change in outcomes. The results show that we can often be deceived by what we think we see and they also demonstrate how such confusion evolves in the literature. This article aims to caution against the over-interpretation of changes from baseline, which are helped along by regression towards the mean and other factors. Furthermore, how we interpret changes from baseline requires care and not wishful thinking, coupled with careful digestion of seemingly reasonable explications of results.

The underrepresentation of female participants in studies assessing the impact of high-dose exercise on cardiovascular outcomes: a scoping review

2021 ◽  
Vol 28 (Supplement_1) ◽  
Author(s):  
S Pallikadavath ◽  
R Patel ◽  
CL Kemp ◽  
M Hafejee ◽  
N Peckham ◽  
...  
Keyword(s):  
Scoping Review ◽  
High Volume ◽  
Cardiovascular Outcomes ◽  
High Dose ◽  
Funding Sources ◽  
Review Protocol ◽  
The Mean ◽  
The Impact ◽  
Over Time ◽  
Funding Acknowledgements

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Cardiovascular adaptations as a result of exercise conducted at high-intensity and high-volume are often termed the ‘Athlete’s heart’. Studies have shown that these cardiovascular adaptations vary between sexes. It is important that both sexes are well represented in this literature. However, many studies assessing the impact of high-dose exercise on cardiovascular outcomes under-recruit female participants. Purpose This scoping review aimed to evaluate the representation of females in studies assessing the impact of high-dose exercise on cardiovascular outcomes and demonstrate how this has changed over time. Methods The scoping review protocol as outlined by Arksey and O’Malley was used. OVID and EMBASE databases were searched and studies independently reviewed by two reviewers. Studies must have investigated the effects of high-dose exercise on cardiovascular outcomes. To assess how the recruitment of females has changed over time, two methods were used. One, the median study date was used to categorise studies into two groups. Two, studies were divided into deciles to form ten equal groups over the study period. Mean percentage of female recruitment and percentage of studies that failed to include females were calculated. Results Overall, 250 studies were included. Over half the studies (50.8%, n = 127) did not include female participants. Only 3.2% (n = 8) did not include male participants. Overall, mean percentage recruitment was 18.2%. The mean percentage of recruitment was 14.5% before 2011 and 21.8% after 2011. The most recent decile of studies demonstrated the highest mean percentage of female recruitment (29.3%) and lowest number of studies that did not include female participants (26.9%). Conclusion Female participants are significantly underrepresented in studies assessing cardiovascular outcomes caused by high-dose exercise. The most recent studies show that female recruitment may be improving, however, this still falls significantly short for equal representation. Risk factors, progression and management of cardiovascular diseases vary between sexes, hence, translating findings from male dominated data is not appropriate. Future investigators should aim to establish barriers and strategies to optimise fair recruitment. Mean percentage females recruited per study (%) Percentage studies that do not include women (%) Overall (n = 250) 18.2 50.8 (n = 127) Studies before 2011 (n = 121) 14.5 59.5 (n = 72) Studies after 2011 (n = 129) 21.8 42.6 (n = 55) Table 1: Female recruitment characteristics. The year 2011 (median study year) was chosen as this divides all included studies into two equal groups.

scholarly journals 134 Long-Term Deutetrabenazine Treatment Is Associated with Sustained Treatment Response in Tardive Dyskinesia: Results from an Open-Label Extension Study

CNS Spectrums ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 284-285 ◽  
Author(s):  
Robert A. Hauser ◽  
Hadas Barkay ◽  
Hubert H. Fernandez ◽  
Stewart A. Factor ◽  
Joohi Jimenez-Shahed ◽  
...  
Keyword(s):  
Adverse Events ◽  
Percentage Change ◽  
Extension Study ◽  
Total Daily Dose ◽  
Open Label ◽  
Daily Dose ◽  
Open Label Extension ◽  
The Mean ◽  
Over Time

Abstract:Background:In the 12-week ARM-TD and AIM-TD studies evaluating deutetrabenazine for the treatment of tardive dyskinesia (TD), the percentage of patients achieving ≥50% response was higher in the deutetrabenazine-treated group than in the placebo group. These studies also showed low rates of overall adverse events (AEs) and discontinuations associated with deutetrabenazine. The current open-label study evaluated the long-term efficacy and safety of deutetrabenazine in patients with TD.Methods:Patients with TD who completed ARM-TD or AIM-TD could enroll in this open-label, single-arm extension study, titrating up over 6 weeks to a maximum total daily dose of deutetrabenazine 48 mg/day on the basis of dyskinesia control and tolerability. The proportion of Abnormal Involuntary Movement Scale (AIMS; items 1-7) responders was assessed based on response rates for achieving ≥50% improvement from baseline in the open-label extension study. AlMS score was assessed by local site raters for this analysis.Results:343 patients enrolled in the extension study. At Week 54 (n=249; total daily dose [mean ± standard error]: 38.6±0.66 mg), the mean percentage change from baseline in AIMS score was –40%; 48% of patients achieved a ≥50% response and 59% of those had already achieved a ≥50% response at Week 15. Further, 34% of those who had not achieved a ≥50% response at Week 15 achieved a ≥50% response at Week 54. At Week 106 (n=169; total daily dose: 39.6±0.77 mg), the mean percentage change from baseline in AIMS score was –45%; 55% of patients achieved a ≥50% response, 59% of those patients had already achieved a ≥50% response at Week 15, and 41% of those who had not achieved a ≥50% response at Week 15 but who reached Week 106 achieved a ≥50% response. At Week 132 (n=109; total daily dose: 39.7±0.97 mg), the mean percentage change from baseline in AIMS score was –61%; 55% of patients achieved a ≥50% response, 61% of those patients had already achieved a ≥50% response at Week 15, and 43% of those who had not achieved a ≥50% response at Week 15 but who reached Week 132 achieved a ≥50% response. Completer analysis suggests that long-term efficacy was not due to dose increases over time. Treatment with deutetrabenazine was generally well tolerated. There were 623 patient-years of exposure through Week 158, and exposure-adjusted incidence rates (incidence/patient-years) of adverse events of special interest were 0.01 for akathisia and restlessness, 0.07 for somnolence and sedation, 0.04 for parkinsonism, and 0.05 for depression.Conclusions:Patients who received long-term treatment with deutetrabenazine achieved response rates that were indicative of clinically meaningful long-term benefit. Results from this open-label trial suggest the possibility of increasing benefit over time with individual dose titration of deutetrabenazine.Funding Acknowledgements:This study was funded by Teva Pharmaceuticals, Petach Tikva, Israel.

scholarly journals Controlling for baseline telomere length biases estimates of the rate of telomere attrition

2019 ◽  
Vol 6 (10) ◽  
pp. 190937 ◽  
Author(s):  
Melissa Bateson ◽  
Dan T. A. Eisenberg ◽  
Daniel Nettle
Keyword(s):  
Measurement Error ◽  
Telomere Length ◽  
Statistical Models ◽  
Meta Analysis ◽  
Regression To The Mean ◽  
Inference Models ◽  
Telomere Attrition ◽  
The Mean ◽  
Invalid Inference ◽  
Over Time

Longitudinal studies have sought to establish whether environmental exposures such as smoking accelerate the attrition of individuals' telomeres over time. These studies typically control for baseline telomere length (TL) by including it as a covariate in statistical models. However, baseline TL also differs between smokers and non-smokers, and telomere attrition is spuriously linked to baseline TL via measurement error and regression to the mean. Using simulated datasets, we show that controlling for baseline TL overestimates the true effect of smoking on telomere attrition. This bias increases with increasing telomere measurement error and increasing difference in baseline TL between smokers and non-smokers. Using a meta-analysis of longitudinal datasets, we show that as predicted, the estimated difference in telomere attrition between smokers and non-smokers is greater when statistical models control for baseline TL than when they do not, and the size of the discrepancy is positively correlated with measurement error. The bias we describe is not specific to smoking and also applies to other exposures. We conclude that to avoid invalid inference, models of telomere attrition should not control for baseline TL by including it as a covariate. Many claims of accelerated telomere attrition in individuals exposed to adversity need to be re-assessed.

scholarly journals Substance Use Among Patients Receiving Out- and Inpatient Dependence Care: a Prospective Norwegian Cohort Study From 2016 to 2020

2021 ◽  
Author(s):  
Jørn Henrik Vold ◽  
Fatemeh Chalabianloo ◽  
Christer F. Aas ◽  
Else-Marie Løberg ◽  
Kjell Arne Johansson ◽  
...  
Keyword(s):  
Substance Use ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Severity Index ◽  
Future Research ◽  
Opioid Agonist ◽  
Low Threshold ◽  
The Mean ◽  
The Impact ◽  
Over Time

Abstract BackgroundContinuous use of amphetamines, alcohol, benzodiazepines, cannabis, cocaine, or opioids contributes to health impairments, increased morbidity, and overdose deaths among patients with substance use disorders (SUDs). This study evaluates the impact of inpatient detoxification, specialized opioid agonist therapy (OAT), and low-threshold municipality care on substance use over time. MethodsWe used data from a cohort of SUD patients in Norway through health assessments of self-reported substance use and sociodemographic and clinical factors. A total of 881 substance use measurements, including type and amount of substances, were assessed from 708 SUD patients in 2016-2020. Substance use for individual and total substances was calculated, creating a substance use severity index (SUSI) ranging from zero (no use) to one (daily use). We defined baseline as the first substance use measurement when the measurements were listed chronologically. Time was defined as years from baseline. We used a linear mixed model to analyze associations between the SUSI and inpatient detoxification, specialized OAT compared with low-threshold municipality care, as well as the factors like injecting substance use, gender, and age, presented with coefficients and 95% confidence intervals (CI).ResultsNeither inpatient detoxification (mean SUSI change: 0.01, -0.03;0.04) nor specialized OAT (0.03, -0.09;0.14) compared with low-threshold municipality care were associated with changes in substance use over time. Patients who were over 60 years of age (mean SUSI difference: -0.06, -0.13;0.00) had a lower SUSI than those under 30 years of age, while patients who injected substances had a higher SUSI than those who did not inject substances (0.18, 0.15;0.20) at baseline. The mean SUSI for the individual substances were 0.50 (standard deviation (SD): 0.38) for cannabis, 0.40 (0.37) for benzodiazepines, 0.33 (0.34) for amphetamines and cocaine, 0.31 (0.29) for alcohol, and 0.22 (0.31) for opioids at baseline. The mean SUSI of all substances was 0.35 (0.20). Conclusion The present study demonstrates that neither inpatient detoxification nor specialized OAT compared to low-threshold municipality care were associated with changes in substance use over time. Future research needs to evaluate the impact on substance use and healthy survival of multiple health care interventions to this patient group.

Linear regression and correlation

2017 ◽  
Author(s):  
Andrew Gelman ◽  
Deborah Nolan
Keyword(s):  
Standard Deviation ◽  
Linear Regression ◽  
Regression Line ◽  
World Population ◽  
Regression To The Mean ◽  
Straight Line ◽  
The Mean ◽  
Line Fitting ◽  
Single Predictor ◽  
Over Time

This chapter addresses the descriptive treatment of linear regression with a single predictor: straight-line fitting, interpretation of the regression line and standard deviation, the confusing phenomenon of “regression to the mean,” correlation, and conducting regressions on the computer. These concepts are illustrated with student discussions and activities. Many examples are of the sort commonly found in statistics textbooks, but the focus here is on how to work the examples into student-participation activities rather than simply examples to be read or shown on the blackboard. Topics include the following relationships: height and income, height and hand span, world population over time, and exam scores.

Chronic pain in multiple sclerosis: A10-year longitudinal study

2017 ◽  
Vol 16 (1) ◽  
pp. 198-203 ◽  
Author(s):  
Jamie Young ◽  
Bhasker Amatya ◽  
Mary P. Galea ◽  
Fary Khan
Keyword(s):  
Quality Of Life ◽  
Multiple Sclerosis ◽  
Chronic Pain ◽  
Longitudinal Study ◽  
The Mean ◽  
The Impact ◽  
Over Time

AbstractBackground and purposePain is a common symptom associated with multiple sclerosis (MS), and has lasting effects on an individual’s functional capacity and quality of life. A wide range of prevalence rates of pain (between 23% and 90%)have been reported in MS and this is mainly due to the methodological differences amongst the studies such as variability in patient sources, method of sampling and the definition of pain used. Chronic pain in MS, defined as pain lasting for greater than 3–6 months, can have a significant impact on their biopsychosocial health, including negative impact on activities of daily living, relationships and social participation. The long-term course of MS-related pain and its impact in an Australian cohort over a 7-year period has been investigated earlier. The aim of this longitudinal study was to describe the impact of chronic pain, pain-related disability and carer burden in persons with MS over a 10-year period. The aim of this longitudinal study was to describe the impact of chronic pain, pain-related disability and carer burden in persons with MS over a 10-year period.MethodsThis was a prospective longitudinal study conducted at the Rehabilitation Department of Royal Melbourne Hospital (RMH), a tertiary referral hospital in Victoria and Australia. The source of participants was from the RMH MS database and contains detailed MS patient information including demographic data, diagnosis details (using McDonald’s criteria), pain characteristics. Structured face-face interviews and validated measures were used, which include the visual analogue scale (VAS); chronic pain grade (CPG); the assessment of quality of life (AQoL) and the carer strain index (CSI). The mean age of the participants (n = 70) was 55.3 years and majority (70%) were female.ResultsThe mean age of the participants (n = 70) was 55.3 years and majority (70%) were female. The findings show that over time (10 years), participants report having greater bilateral bodily pain and greater description of pain as ‘worse as it could be’. Pain types were similar to 7-years follow-up but remained higher than baseline. There was a significant deterioration in quality of life in those with more severe CPG over time. Almost half of the participants 31 (44%) required care either from a private carer, institution or from a family member. Although fear of taking medications and side effects were common barriers to treatment for pain, there was an increase in the use of pharmacological treatment over time and an increase in the use of healthcare services, mainly neurologists and general practitioners.ConclusionsThe pain measures reported by the participants were similar to those at the 7-year follow-up except there was a greater representation of bilateral pain locations (limb, trunk and facial pain) compared to baseline and 7-year follow-up. At 10-year follow-up, more participants used medications compared tc 7-year follow-up and there was an increase in the use of health professionals at the 10-year follow-up At the 10-year follow up QoL of the participants deteriorated significantly and more participants had progressed to higher CPGIII and CPGIV. This study demonstrates that chronic pain is a significant issue over time in MS, with clinical and health implications, impact on quality of life, disability and healthcare utilization.ImplicationsGreater awareness of chronic pain in pwMS, cognitive classifications and an interdisciplinary approach is required to improve long-term patient outcomes and well-being.Crown Copyright © 2017 Published by Elsevier B.V. on behalf of Scandinavian Association for the Study of Pain. All rights reserved.

The Impact of Intraoperative Manipulation of the Prostate on Total and Free Prostate-Specific Antigen

2002 ◽  
Vol 17 (3) ◽  
pp. 154-160 ◽  
Author(s):  
F. Oberpenning ◽  
H.-P. Schmid ◽  
W. Fuchs-Surdel ◽  
L. Hertle ◽  
A. Semjonow
Keyword(s):  
Specific Antigen ◽  
Rapid Decline ◽  
Response Ratio ◽  
Substantial Impact ◽  
Blood Samples ◽  
Free Psa ◽  
The Mean ◽  
Total Psa ◽  
The Impact ◽  
Over Time

Objectives It is well documented that mechanical manipulation of the prostate can elevate total PSA (t-PSA) levels in serum. However, less is known about its effects on free PSA (f-PSA) and the free-to-total PSA ratio (f/t-PSA). We therefore examined the impact of prostate manipulation on t-PSA and f-PSA during surgical procedures involving the prostate. Methods Intraoperative blood samples for t-PSA and f-PSA measurement (Hybritech) were collected every 15 min during 14 radical retropubic prostatectomies (RRP) and 10 radical cystoprostatectomies (RCP). Results Prostatic manipulation induced significant elevations in t-PSA and f-PSA during RRP and RCP. Postmanipulatory peaks were markedly higher for f-PSA than for t-PSA. The mean maximum f-PSA levels showed a 4.3- (RRP) and 7.9-fold (RCP) increase, followed by a rapid decline after prostate removal. t-PSA increased 1.2- (RRP) and 1.3-fold (RCP), and declined more slowly. Postmanipulatory f/t-PSA ratios also increased significantly, reaching mean elevations of +0.29 and +0.28 over preoperative ratios during RRP and RCP, respectively. Conclusions Prostate manipulation can induce transient increases in t-PSA, f-PSA and f/t-PSA in benign and malignant prostates. The extent of these alterations and their course over time must be taken into account when postmanipulatory changes in PSA forms are investigated. Timing of postmanipulatory venipunctures and the molar response ratio of t-PSA assays used (equimolar versus nonequimolar) seem to have substantial impact on the results of such studies.

The Impact of STRICTA and CONSORT on Reporting of Randomised Control Trials of Acupuncture: A Systematic Methodological Evaluation

2018 ◽  
Vol 36 (6) ◽  
pp. 349-357 ◽  
Author(s):  
Simen Svenkerud ◽  
Hugh MacPherson
Keyword(s):  
Positive Impact ◽  
Meta Analysis ◽  
Reporting Quality ◽  
Primary Analysis ◽  
Quality Of Reporting ◽  
The Mean ◽  
Time Periods ◽  
The Impact ◽  
Over Time

Background Clear and unambiguous reporting is essential for researchers and clinicians to be able to assess the quality of research. To enhance the quality of reporting, consensus-based reporting guidelines are commonly used. Objectives To update and extend previous research by evaluating the more recent impact of STRICTA (STandards for Reporting Interventions in Controlled Trials of Acupuncture) and CONSORT (CONsolidated Standards Of Reporting Trials) guidelines on the quality of reporting of acupuncture trials. Methods By random sampling, approximately 45 trials from each of five 2-year time periods between 1994 and 2015 were included in the study. Using scoring sheets based on the STRICTA and CONSORT checklist items (range 0 to 7 and 0 to 5, respectively), the distribution of items reported over time was investigated, with changes shown using scatterplots. The primary analysis used a before-and-after t-test to compare time periods. A meta-analysis investigated whether or not trials published in journals that endorsed STRICTA were associated with better reporting. Results The study included 207 trials. Improved reporting of items over time was observed, as represented by changes in the scatterplot slope and intercept. The mean STRICTA score increased from 4.27 in the 1994–1995 period to 5.53 in 2014–2015, an 18% improvement. The mean CONSORT score rose from 1.01 in the 1994–1995 period to 3.32 in 2014–2015, an increment of 46%. There was proportionately lower reporting for items related to practitioner background (STRICTA) and for randomisation implementation and allocation concealment (CONSORT). Trials published in journals that endorsed STRICTA had statistically significantly superior reporting of both STRICTA and CONSORT items overall. Conclusion This study has provided evidence of an improvement in reporting of STRICTA and CONSORT items over the time period from 1994 to 2015. Journals that endorse STRICTA have a better record in terms of reporting quality. Some evidence suggests that the publication of STRICTA has had a positive impact on reporting quality.

Physiological changes in the size of the septal swell body correlate with changes in inferior turbinate size

2020 ◽  
Vol 134 (4) ◽  
pp. 323-327
Author(s):  
E H Wong ◽  
M Noussair ◽  
Z Hasan ◽  
M Duvnjak ◽  
N Singh
Keyword(s):  
Middle Turbinate ◽  
Inferior Turbinate ◽  
Normal Function ◽  
Mean Difference ◽  
Nasal Breathing ◽  
Area Of Interest ◽  
The Mean ◽  
The Difference ◽  
The Impact ◽  
Over Time

AbstractObjectiveThe nasal septal swell body is a normal anatomical structure located in the superior nasal septum anterior to the middle turbinate. However, the impact of the septal swell body in nasal breathing during normal function and disease remains unclear. This study aimed to establish that the septal swell body varies in size over time and correlates this with the natural variation of the inferior turbinates.MethodConsecutive patients who underwent at least two computed tomography scans were identified. The width and height of the septal swell body and the inferior turbinates was recorded. A correlation between the difference in septal swell body and turbinates between the two scans was performed using a Pearson's coefficient.ResultsA total of 34 patients (53 per cent female with a mean age of 58.3 ± 20.2 years) were included. The mean and mean difference in septal swell body width between scans for the same patient was 1.57 ± 1.00 mm. The mean difference in turbinate width between scans was 2.23 ± 2.52 mm. A statistically significant correlation was identified between the difference in septal swell body and total turbinate width (r = 0.35, p = 0.04).ConclusionThe septal swell body is a dynamic structure that varies in width over time in close correlation to the inferior turbinates. Further research is required to quantify its relevance as a surgical area of interest.

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