scholarly journals Many continuous variables should be analyzed using the relative scale: a case study of β2-agonists for preventing exercise-induced bronchoconstriction

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Harri Hemilä ◽  
Jan O. Friedrich
Keyword(s):  
Meta Analysis ◽  
Relative Effect ◽  
Similar Amount ◽  
Mixed Effect ◽  
Absolute Scale ◽  
Effect Model ◽  
Absolute Effect ◽  
The Absolute ◽  
Relative Scale ◽  
Exercise Induced

Abstract Background The relative scale adjusts for baseline variability and therefore may lead to findings that can be generalized more widely. It is routinely used for the analysis of binary outcomes but only rarely for continuous outcomes. Our objective was to compare relative vs absolute scale pooled outcomes using data from a recently published Cochrane systematic review that reported only absolute effects of inhaled β2-agonists on exercise-induced decline in forced-expiratory volumes in 1 s (FEV1). Methods From the Cochrane review, we selected placebo-controlled cross-over studies that reported individual participant data (IPD). Reversal in FEV1 decline after exercise was modeled as a mean uniform percentage point (pp) change (absolute effect) or average percent change (relative effect) using either intercept-only or slope-only, respectively, linear mixed-effect models. We also calculated the pooled relative effect estimates using standard random-effects, inverse-variance-weighting meta-analysis using study-level mean effects. Results Fourteen studies with 187 participants were identified for the IPD analysis. On the absolute scale, β2-agonists decreased the exercise-induced FEV1 decline by 28 pp., and on the relative scale, they decreased the FEV1 decline by 90%. The fit of the statistical model was significantly better with the relative 90% estimate compared with the absolute 28 pp. estimate. Furthermore, the median residuals (5.8 vs. 10.8 pp) were substantially smaller in the relative effect model than in the absolute effect model. Using standard study-level meta-analysis of the same 14 studies, β2-agonists reduced exercise-induced FEV1 decline on the relative scale by a similar amount: 83% or 90%, depending on the method of calculating the relative effect. Conclusions Compared with the absolute scale, the relative scale captures more effectively the variation in the effects of β2-agonists on exercise-induced FEV1-declines. The absolute scale has been used in the analysis of FEV1 changes and may have led to sub-optimal statistical analysis in some cases. The choice between the absolute and relative scale should be determined based on biological reasoning and empirical testing to identify the scale that leads to lower heterogeneity.

scholarly journals Effects of Diet, Aerobic Exercise, or Both on Non-HDL-C in Adults: A Meta-Analysis of Randomized Controlled Trials

Cholesterol ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
George A. Kelley ◽  
Kristi S. Kelley
Keyword(s):  
Aerobic Exercise ◽  
Randomized Controlled Trials ◽  
Meta Analysis ◽  
Statistical Significance ◽  
Density Lipoprotein ◽  
Control Group ◽  
Controlled Trials ◽  
Mixed Effect ◽  
Randomized Controlled ◽  
Effect Model

Purpose. To use the meta-analytic approach to examine the effects of diet (D), aerobic exercise (E), or both (DE) on non-high-density lipoprotein cholesterol (non-HDL-C) in adults. Methods. Randomized controlled trials in adults ≥18 years of age were included. A mixed-effect model was used to combine effect size (ES) results within each subgroup and to compare subgroups (Qb). Heterogeneity was examined using the Q and I2 statistics, and 95% confidence intervals (CI) were also calculated. Statistical significance was set at P≤0.05, while a trend for statistical significance was set between P>0.05, and ≤0.10. Results. A statistically significant exercise minus control group decrease in non-HDL-C was found for DE (7 ESs, 389 participants, x¯=-11.1 mg/dL, 95%  CI=−21.7 to −0.6, P=0.04, Q=2.4, P=0.88, I2=0%), a trend for the D group (7 ESs, 402 participants, x¯=−8.5 mg/dL, 95%  CI=−18.6 to 1.6, P=0.10, Q=0.76, P=0.99, I2=0%), and no change for the E group (7 ESs, 387 participants, x¯=3.0 mg/dL, 95%   CI=−7.1 to 13.1, P=0.56, Q=0.78, P=0.99, I2=0%). Overall, no statistically significant between-group differences were found (Qb=4.1, P=0.12). Conclusions. Diet combined with aerobic exercise may reduce non-HDL-C among adults in some settings.

P2482Sex-based differences in cardioprotective role of SGLT-2 inhibitors in patients with type 2 diabetes mellitus

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
N Madan ◽  
S Sohal ◽  
B Parapid ◽  
L Sperling ◽  
J L Januzzi ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Meta Analysis ◽  
Mixed Effect ◽  
Pooled Data ◽  
Major Cardiovascular Events ◽  
Effect Model

Abstract Background Randomized studies have shown that sodium-glucose cotransporter-2 inhibitors (SGLT2i) reduce major cardiovascular events in patients with type 2 diabetes mellitus. However, it is not known whether there are significant sex-based differences in the cardioprotective role of SGLT-2 inhibitors. Purpose To investigate whether sex differences exist in reduction of major cardiovascular events (MACE)in patients with type 2 diabetes mellitus when treated with SGLT2i. Methods A comprehensive PubMed search was conducted using keywords, (“Diabetes” AND (“Dapagliflozin” OR “Empagliflozin” OR “Canagliflozin” OR “Ertugliflozin”) AND “Outcomes”) that resulted in a total of 221 studies. Studies were included in our meta-analysis if they were randomized controlled trials, placebo-controlled, reported MACE as the primary outcome and reported sex-based subgroup analyses of these outcomes. Only 2 RCTs (EMPA-REG and DECLARE-TIMI 58) met our inclusion criteria.The sex-based event data for both trials was pooled to calculate risk ratios (RR) with 95% confidence intervals (CI). Analyses was performed using Comprehensive Meta-analysis (CMA) software. Fixed effect models, random effect models and mixed effect models were used. Results Pooled datafrom the 2 RCTs (EMPA-REG and DECLARE-TIMI 58) resulted in a total of 24,180 patients who were included in our primary analysis. Of these, 2331 patients were reported to have MACE. In our pooled data, SGLT2i reduced MACE in patients with diabetes with an overall risk ratio of 0.92 (0.85–0.99), p=0.03 (I2=0, p=0.31)using fixed effect model (Table 1). We also performed subgroup analysis of the pooled data categorizing by sex and using mixed effect model. Our subgroup analysis by sex showed a Q statistic of 1.88 with p-value of 0.17 suggesting that there is no significant difference in MACE reduction between men and women with diabetes when treated with SGLT2i. However, on further analyzing the sex differences in the individual trials, we found that women may have greater reduction in MACE compared with their male counterparts (RR in females: 0.66 (0.42–1.04); RR in males: 0.92 (0.84–1.00)), however this finding did not meet statistical significance (Table 2). Conclusion Our meta-analysis included the pooled data from 2 major RCTs (EMPA-REG and DECLARE-TIMI 58) assessing the cardioprotective role of SGLT2i in diabetic patients and shows that SGLT2i significantly reduce the risk of major adverse CV events in patients with type 2 diabetes mellitus. However, we did not find any significant sex-based differences in reduction of MACE between men and women with diabetes when treated with SGLT2i.

scholarly journals Meta-analysis of metabolites involved in bioenergetic pathways reveals a pseudohypoxic state in Down syndrome

2020 ◽  
Vol 26 (1) ◽  
Author(s):  
Laszlo Pecze ◽  
Elisa B. Randi ◽  
Csaba Szabo
Keyword(s):  
Down Syndrome ◽  
Meta Analysis ◽  
Experimental Therapy ◽  
Mixed Effect ◽  
Functional Deficits ◽  
Clinical Observations ◽  
Effect Model ◽  
Acid Succinate ◽  
The Difference ◽  
And Control

Abstract Clinical observations and preclinical studies both suggest that Down syndrome (DS) may be associated with significant metabolic and bioenergetic alterations. However, the relevant scientific literature has not yet been systematically reviewed. The aim of the current study was to conduct a meta-analysis of metabolites involved in bioenergetics pathways in DS to conclusively determine the difference between DS and control subjects. We discuss these findings and their potential relevance in the context of pathogenesis and experimental therapy of DS. Articles published before July 1, 2020, were identified by using the search terms “Down syndrome” and “metabolite name” or “trisomy 21” and “metabolite name”. Moreover, DS-related metabolomics studies and bioenergetics literature were also reviewed. 41 published reports and associated databases were identified, from which the descriptive information and the relevant metabolomic parameters were extracted and analyzed. Mixed effect model revealed the following changes in DS: significantly decreased ATP, CoQ10, homocysteine, serine, arginine and tyrosine; slightly decreased ADP; significantly increased uric acid, succinate, lactate and cysteine; slightly increased phosphate, pyruvate and citrate. However, the concentrations of AMP, 2,3-diphosphoglycerate, glucose, and glutamine were comparable in the DS vs. control populations. We conclude that cells of subjects with DS are in a pseudo-hypoxic state: the cellular metabolic and bio-energetic mechanisms exhibit pathophysiological alterations that resemble the cellular responses associated with hypoxia, even though the supply of the cells with oxygen is not disrupted. This fundamental alteration may be, at least in part, responsible for a variety of functional deficits associated with DS, including reduced exercise difference, impaired neurocognitive status and neurodegeneration.

scholarly journals The impacts of hydropower on freshwater macroinvertebrate richness: A global meta-analysis

2021 ◽  
Author(s):  
Gabrielle Trottier ◽  
Katrine Turgeon ◽  
Daniel Boisclair ◽  
Cécile Bulle ◽  
Manuele Margni
Keyword(s):  
Variance Estimation ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Hydroelectric Dams ◽  
Freshwater Biodiversity ◽  
Mixed Effect ◽  
Large Variability ◽  
Effect Model ◽  
Hydropower Dams ◽  
Study Designs

AbstractHydroelectric dams and their reservoirs have been suggested to affect freshwater biodiversity. However, studies investigating the consequences of hydroelectric dams and reservoirs on macroinvertebrate richness have reached opposite conclusions. We carried out a meta-analysis devised to elucidate the effects of hydropower dams and their reservoirs on macroinvertebrates richness while accounting for the potential role played by moderators such as biomes, impact types, study designs, sampling seasons and gears. We used a random and mixed effect model, combined with robust variance estimation, to conduct the meta-analysis on 72 pairs of observations (i.e., impacted versus reference) extracted from 17 studies (more than one observation per study). We observed a large range of effect sizes, from very negative to very positive impacts of hydropower. However, according to this meta-analysis, hydropower dams and their reservoirs did not have an overall clear, directional and statistically significant effect on macroinvertebrate richness. We tried to account for the large variability in effect sizes using moderators, but none of the moderators included in the meta-analysis had statistically significant effect. This suggests that some other moderators, which were unavailable for the 17 studies included in this meta-analysis, might be important (e.g., temperature, granulometry, wave disturbance and macrophytes) and that macroinvertebrate richness may be driven by local, smaller scale processes. As new studies become available, it would be interesting to keep enriching this meta-analysis, as well as collecting local habitat variables, to see if we could finally draw statistically significant conclusions about the impacts of hydropower on macroinvertebrate richness.

scholarly journals A Comparison of the Effects of Foam Rolling and Stretching on Physical Performance. A Systematic Review and Meta-Analysis

2021 ◽  
Vol 12 ◽  
Author(s):  
Andreas Konrad ◽  
Markus Tilp ◽  
Masatoshi Nakamura
Keyword(s):  
Range Of Motion ◽  
Meta Analysis ◽  
Random Effect ◽  
Performance Parameters ◽  
Mixed Effect ◽  
Acute Bout ◽  
Warm Up ◽  
Foam Rolling ◽  
Effect Model ◽  
Subgroup Analyses

Foam rolling and stretching with its various techniques are frequently used as a warm-up routine to increase the range of motion of a joint. While the magnitude of the changes in range of motion between foam rolling and stretching (static and dynamic techniques) is similar, it is not clear if this also holds true for performance parameters (e.g., strength, jump height). The purpose of this meta-analysis was to compare the effects of an acute bout of foam rolling (with and without vibration) with an acute bout of stretching (with all techniques included) on performance parameters in healthy participants. We assessed the results from 13 studies and 35 effect sizes by applying a random-effect meta-analysis. Moreover, by applying a mixed-effect model, we performed subgroup analyses with the stretching technique, type of foam rolling, tested muscle, treatment duration, and type of task. We found no significant overall effect, and the analysis revealed only a trend of the performance parameters in favor of foam rolling when compared to stretching (when considering all techniques). Significantly favorable effects of foam rolling on performance were detected with subgroup analyses when compared to static stretching, when applied to some muscles (e.g., quadriceps) or some tasks (e.g., strength), when applied for longer than 60 s, or when the foam rolling included vibration. When foam rolling was compared to dynamic stretching or applied in the non-vibration mode, the same magnitude of effect was observed. While the present meta-analysis revealed no significantly different effect between foam rolling and stretching (including all techniques) prior to exercise, differences could be observed under specific conditions.

Supportive care and chemotherapy (CT) versus supportive care alone in advanced non-small cell lung cancer (NSCLC): A meta-analysis using individual patient data (IPD) from randomised clinical trials (RCTs)

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 7582-7582 ◽  
Author(s):  
S. Burdett ◽  
L. A. Stewart ◽  
J. F. Tierney ◽  
C. Le Pechoux
Keyword(s):  
Supportive Care ◽  
Meta Analysis ◽  
Alkylating Agents ◽  
Performance Status ◽  
Single Agent ◽  
Rank Test ◽  
Absolute Benefit ◽  
Absolute Effect ◽  
The Absolute ◽  
Treatment Comparisons

7582 Background: Building on a previous IPD meta-analysis of CT (BMJ 1995;311:899–909) which suggested that CT may have a role in the treatment of NSCLC, we have carried out a new, up-to-date IPD meta-analysis. This includes RCTs, regimens and outcomes that were not available in 1995. This new meta-analysis examines the role of CT in 7 treatment comparisons. Here we report the effectiveness of supportive care plus CT compared with supportive care alone. Methods: We conducted a systematic search for RCTs followed by the central collection, checking and re-analysis of updated IPD. Results from individual RCTs were combined using the stratified (by trial) log rank test to calculate individual and pooled hazard ratios (HRs). Previously included RCTs using long-term alkylating agents were excluded from this analysis due to their antiquity. Results: IPD were obtained on 2,666 patients from 15 RCTs. 11 RCTs used cisplatin-based CT regimens, 4 RCTs used single agent CT (etoposide, navelbine, gemcitabine, paclitaxel). This added 6 RCTs and 1,702 patients to the 1995 analyses. The results show a highly significant benefit of CT on survival (HR=0.78 95% Confidence Interval 0.71–0.84, p<0.000001), with an absolute benefit of 8% (from 20% to 28%) at 12 months across all patients. There was no evidence of a difference in effect (p=0.69) between trials that used cisplatin-based regimens (11 RCTs, HR=0.76), etoposide alone (1 RCT, HR=0.87) or newer single agents (3 RCTs, HR=0.79) (Interaction p=0.69). There was no evidence that any patient subgroup defined by age, sex, stage or histology benefited more or less from CT. The absolute benefit of CT at 12 months did vary according to WHO/ECOG (or equivalent) performance status. PS 0=8% (from 26% to 34%), PS 1=8% (from 18% to 26%), PS 2=5% (from 6% to 11%) and PS 3=4% (from 5% to 9%). Conclusion: The results demonstrate a substantial and consistent relative benefit of CT in advanced NSCLC. The effectiveness of newer agents such as navelbine, paclitaxel and gemcitabine (used as single agents) appears to be similar to that of cisplatin combined with older agents such as vindesine and mitomycin C. The absolute effect of CT varied according to performance status. No significant financial relationships to disclose.

Extending the Capability of the Greenwood Williamson Microcontact Model

2000 ◽  
Vol 122 (3) ◽  
pp. 496-502 ◽  
Author(s):  
John I. McCool
Keyword(s):  
Simulation Model ◽  
Coating Thickness ◽  
Surface Coating ◽  
Relative Effect ◽  
Compliant Coating ◽  
Absolute Effect ◽  
The Mean ◽  
The Absolute

This paper describes a readily implemented simulation model that extends the Greenwood Williamson microcontact model to include skewness in the distribution of surface summit heights and the presence of a surface coating of prescribed thickness and compliance. Parametric runs were made to explore the effect of these factors on the load, area and mean real pressure at the contacting asperities for a fixed separation of the mean planes of the contacting surfaces such as occurs when the surfaces are separated by a stiff elastohydrodynamic film. It was found that the average asperity load increases with coating thickness when the coating is stiffer than the substrate and decreases when the coating is made more compliant. The opposite is true for the average asperity area of contact. Like load, the average asperity pressure increases with coating thickness when the coating is stiffer than the substrate and decreases when the coating is more compliant. For the same rms summit height the mean asperity pressure in the absence of a coating was found to be higher by a factor of 1.6 when the skewness is +1 than when it is −1. The relative effect of skewness on pressure is practically constant as coating thickness increases for the compliant coating while the absolute effect decreases. For the stiff coating the absolute effect is constant while the relative effect diminishes. [S0742-4787(00)02303-1]

scholarly journals Meta-Analysis of Changes in Sleep Quality of Women with Breast Cancer before and after Therapy

Breast Care ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 227-235
Author(s):  
Wen-Pei Chang ◽  
Yu-Pei Chang
Keyword(s):  
Breast Cancer ◽  
Sleep Quality ◽  
Meta Analysis ◽  
Linear Mixed Effect Model ◽  
Cancer Treatments ◽  
Mixed Effect ◽  
Effect Model ◽  
Before And After ◽  
Mean Differences

Cancer treatments may affect the sleep quality and even future quality of life of women with breast cancer. A meta-analysis was performed to understand the changes in the sleep quality of women with breast cancer during their treatment period. In a systematic literature review in compliance with the PRISMA guidelines, we searched for articles published between 2000 and 2018 in databases. A total of 12 study articles were included. The standardized mean differences of the pooling effect size of sleep quality between the period before treatment and 1–8 weeks, 9–16 weeks, 17–24 weeks, and 25–56 weeks after the commencement of treatment were –0.020, –0.162, 0.075, and 0.216, respectively. Although the differences were not statistically significant, in view of the heterogeneity among the studies, we conducted further analysis using a linear mixed effect model. The overall results indicated poorer sleep quality as time passed from the start of the first treatment (p = 0.014). The results of this study revealed that patients experienced better sleep quality in the initial months after the beginning of treatment; however, their sleep quality became poorer between 4 months to approximately 1 year after the beginning of treatment, compared with the sleep quality before treatment, and continued to decline rather than improve during the follow-up period.

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