Significant Summary Effect Size Research Articles

The redundant target paradigm and its use as a blindsight-test: A meta-analytic study

The redundant target effect (RTE) is the well-known effect whereby a single target is detected faster when a second, redundant target is presented simultaneously. The RTE was shown in different experimental designs and applied in various clinical contexts. However, there are also studies showing non-effects or effects in the opposite direction. Our meta-analysis aims to investigate the replicability of the RTE. Herein, we focused on the clinical context within which the RTE has been applied most often and for which it gained particular prominence: The research on blindsight and other forms of residual vision in patients with damage to the neuronal visual system. The application of the RTE in clinical contexts assumes that whenever vision is present, an RTE will be found. Put differently, the RTE as a tool to uncover residual vision presumes that the RTE is a consistent feature of vision in the healthy population. We found a significant summary effect size of the RTE in healthy participants. The effect size depended on certain experimental features: task type, target configuration in the redundant condition, and how reaction times were computed in the single condition. A specific feature combination is typically used in blindsight research. Analyzing studies with this feature combination revealed a significant summary effect size in healthy participants predicting positive RTEs for future studies. A power-analysis revealed a required sample size of 14 participants to obtain an RTE with high reliability. However, the required sample size is rarely reached in blindsight research. Rather, blindsight research is mostly based on single-case studies. In summary, the RTE is a robust effect on group level but does not occur in every single individual. This means failure to obtain an RTE in a single patient should not be interpreted as evidence for the absence of residual vision in this patient.

Sensory retraining of the leg after stroke: systematic review and meta-analysis

Objective: This systematic review aimed to investigate the effects of interventions intended for retraining leg somatosensory function on somatosensory impairment, and secondary outcomes of balance and gait, after stroke. Data sources: Databases searched from inception to 16 January 2019 included Cochrane Library, PubMed, MEDLINE, CINAHL, EMBASE, PEDro, PsycINFO, and Scopus. Reference lists of relevant publications were also manually searched. Review methods: All types of quantitative studies incorporating interventions that intended to improve somatosensory function in the leg post stroke were retrieved. The Quality Assessment Tool for Quantitative Studies was used for quality appraisal. Standardised mean differences were calculated and meta-analyses were performed using preconstructed Microsoft Excel spreadsheets. Results: The search yielded 16 studies, comprising 430 participants, using a diverse range of interventions. In total, 10 of the included studies were rated weak in quality, 6 were rated moderate, and none was rated strong. Study quality was predominantly affected by high risk of selection bias, lack of blinding, and the use of somatosensory measures that have not been psychometrically evaluated. A significant heterogeneous positive summary effect size (SES) was found for somatosensory outcomes (SES: 0.52; 95% confidence interval (CI): 0.04 to 1.01; I2 = 74.48%), which included joint position sense, light touch, and two-point discrimination. There was also a significant heterogeneous positive SES for Berg Balance Scale scores (SES: 0.62; 95% CI: 0.10 to 1.14; I2 = 59.05%). Gait SES, mainly of gait velocity, was not significant. Conclusion: This review suggests that interventions used for retraining leg somatosensory impairment after stroke significantly improved somatosensory function and balance but not gait.

Meta-Analysis of BDNF Levels in Autism.

Brain-derived neurotrophic factor (BDNF) centrally mediates growth, differentiation and survival of neurons, and the synaptic plasticity that underlies learning and memory. Recent meta-analyses have reported significantly lower peripheral BDNF among individuals with schizophrenia, bipolar disorder, and depression, compared with controls. To evaluate the role of BDNF in autism, and to compare autism to psychotic-affective disorders with regard to BDNF, we conducted a meta-analysis of BDNF levels in autism. Inclusion criteria were met by 15 studies, which included 1242 participants. The meta-analysis estimated a significant summary effect size of 0.33 (95% CI 0.21-0.45, P<0.001), suggesting higher BDNF in autism than in controls. The studies showed notable heterogeneity, but no evidence of publication biases. Higher peripheral BDNF in autism is concordant with several neurological and psychological theories on the causes and symptoms of this condition, and it contrasts notably with the lower levels of BDNF found in schizophrenia, bipolar disorder, and depression.

Meta-analyses of habitat selection by fishers at resting sites in the pacific coastal region

The fisher (Pekania pennanti) is a species of conservation concern throughout the Pacific coastal region in North America. A number of radiotelemetry studies of habitat selection by fishers at resting sites have been conducted in this region, but the applicability of observed patterns beyond the boundaries of each study area is unknown. Broadly applicable information on habitat selection by fishers in this region would be useful for conservation planning and for informing forest management decisions in areas where intensive field studies have not been conducted. To provide such information, we conducted formal meta-analyses of habitat selection by fishers at resting sites in 8 study areas located from central British Columbia to the southern Sierra Nevada in California, including all areas that currently contain established fisher populations. Each study included in the meta-analyses measured environmental attributes at sites used by fishers for resting (i.e., the immediate vicinity of resting structures; typically ≤0.5 ha) and at random or systematically located sites representing resource availability in each study area. We selected 9 environmental attributes that we expected to be associated with fisher resting sites: slope, heat load index, percent cover of vegetation ≥2 m above the ground, volume of moderately decayed logs ≥26 cm in mean diameter, basal area of live conifers 51–100 cm in diameter at breast height (dbh), basal area of live hardwoods 51–100 cm in dbh, basal area of moderately decayed snags 51–100 cm in dbh, mean dbh of live conifers ≥10 cm in dbh, and mean dbh of live hardwoods ≥10 cm in dbh. Despite substantial variation in environmental conditions among study locations, our analyses revealed statistically significant summary effect sizes for each of the 9 environmental attributes we analyzed. Fishers selected sites for resting that had steeper slopes, cooler microclimates, denser overhead cover, a greater volume of logs, and a greater prevalence of large trees and snags than were generally available. Thus, in areas within the Pacific coastal region where fishers have not been studied and data on selection of resting sites are lacking, our findings provide empirical support for management or conservation actions for fishers that promote the retention or development of these environmental attributes. © 2013 The Wildlife Society.

Evaluation of Excess Statistical Significance in Meta-analyses of 98 Biomarker Associations with Cancer Risk

Numerous biomarkers have been associated with cancer risk. We assessed whether there is evidence for excess statistical significance in results of cancer biomarker studies, suggesting biases. We systematically searched PubMed for meta-analyses of nongenetic biomarkers and cancer risk. The number of observed studies with statistically significant results was compared with the expected number, based on the statistical power of each study under different assumptions for the plausible effect size. We also evaluated small-study effects using asymmetry tests. All statistical tests were two-sided. We included 98 meta-analyses with 847 studies. Forty-three meta-analyses (44%) found nominally statistically significant summary effects (random effects). The proportion of meta-analyses with statistically significant effects was highest for infectious agents (86%), inflammatory (67%), and insulin-like growth factor (IGF)/insulin system (52%) biomarkers. Overall, 269 (32%) individual studies observed nominally statistically significant results. A statistically significant excess of the observed over the expected number of studies with statistically significant results was seen in 20 meta-analyses. An excess of observed vs expected was observed in studies of IGF/insulin (P ≤ .04) and inflammation systems (P ≤ .02). Only 12 meta-analyses (12%) had a statistically significant summary effect size, more than 1000 case patients, and no hints of small-study effects or excess statistical significance; only four of them had large effect sizes, three of which pertained to infectious agents (Helicobacter pylori, hepatitis and human papilloma viruses). Most well-documented biomarkers of cancer risk without evidence of bias pertain to infectious agents. Conversely, an excess of statistically significant findings was observed in studies of IGF/insulin and inflammation systems, suggesting reporting biases.

Effects of Augmented Exercise Therapy on Outcome of Gait and Gait-Related Activities in the First 6 Months After Stroke

The purpose of this study was to determine the effects of augmented exercise therapy on gait, gait-related activities, and (basic and extended) activities of daily living within the first 6 months poststroke. A systematic literature search in electronic databases from 1990 until October 2010 was performed. Randomized controlled trials were included in which the experimental group spent augmented time in lower-limb exercise therapy compared with the control group. Outcomes were gait, gait-related activities, and (extended) activities of daily living. Results from individual studies were pooled by calculating the summary effect sizes. Subgroup analyses were applied for a treatment contrast of ≥16 hours, timing poststroke, type of control intervention, and methodological quality. Fourteen (N=725) of 4966 identified studies were included. Pooling resulted in small to moderate significant summary effect sizes in favor of augmented exercise therapy for walking ability, comfortable and maximum walking speed, and extended activities of daily living. No significant effects were found for basic activities of daily living. Subgroup analysis did not show a significant effect modification. Dose-response trials in stroke rehabilitation are heterogeneous. The present meta-analysis suggests that increased time spent on exercise of gait and gait-related activities in the first 6 months poststroke results in significant small to moderate effects in terms of walking ability, walking speed, and extended activities of daily living. High-quality dose-response exercise therapy trials are needed with identical treatment goals but incremental levels of intensity.

The Impact of Increased Duration of Exercise Therapy on Functional Recovery Following Stroke — What Is the Evidence?

This article focuses on the impact of increased duration of exercise therapy on functional recovery after stroke. A comprehensive literature search using multiple databases was used to identify all relevant randomized controlled trials. Their quality was reviewed by two independent assessors, and a narrative systematic review and meta-analysis was completed. Methodological quality of all the 20 randomized controlled trials (RCTs) identified had a median of 6 points (range 5–8) on the 10-point PEDro scale. A meta-analysis was completed for studies that had a common outcome measure. For each outcome measure, the estimated effect size (ES) and the summary effect size (SES) were expressed as standardized mean differences (SMD). The results of the meta-analysis demonstrated that increased duration of exercise therapy time has a small but positive effect on activities of daily living as measured by the Barthel Index (SES 0.13; CI 0.01–0.25; Z = 2.15; p = .03) and that these improvements are maintained over a 6-month period (SES 0.15; CI 0.05–0.26; Z = 2.8; p = .00). Pooling reported differences in the various upper and lower extremity outcome measures demonstrated no significant SESs. However, the meta-analysis is supportive of the hypothesis that additional, focused exercise on the lower extremity has a favourable effect on lower extremity impairment and walking speed. The narrative review raises a number of issues that need to be considered in the development of future RCTs.

Examining the Evidence on Neuromuscular Electrical Stimulation for Swallowing

To evaluate the effect of transcutaneous neuromuscular electrical stimulation (NMES) on swallowing rehabilitation. MEDLINE, PubMed, CINAHL, NML, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, doc online, Google, and EMBASE were searched for studies using NMES to treat dysphagia between January 1966 and August 2006. Included were published or unpublished, English-language, clinical trials with a quantifiable dependent variable. Two researchers independently performed data extraction. A random-effects model was used to pool study results. The Cochran Q test was used to evaluate heterogeneity, and a funnel plot and Egger test were used to evaluate publication bias. A best-research synthesis using a methodological quality analysis was conducted. A total of 81 studies were reviewed. Seven were accepted for analysis. A significant summary effect size was identified for the application of NMES for swallowing (Hedges g, 0.66; P<.001). Heterogeneity was significant for the combined trials (P<.10). When 2 outlier trials were removed, heterogeneity was no longer significant (P<.08). Publication bias was not identified on the funnel plot or Egger test (P = .25). Best-evidence synthesis showed indicative findings in favor of NMES for swallowing. This preliminary meta-analysis revealed a small but significant summary effect size for transcutaneous NMES for swallowing. Because of the small number of studies and low methodological grading for these studies, caution should be taken in interpreting this finding. These results support the need for more rigorous research in this area.

Effects of augmented exercise therapy time after stroke: a meta-analysis.

To present a systematic review of studies that addresses the effects of intensity of augmented exercise therapy time (AETT) on activities of daily living (ADL), walking, and dexterity in patients with stroke. A database of articles published from 1966 to November 2003 was compiled from MEDLINE, CINAHL, Cochrane Central Register of Controlled Trials, PEDro, DARE, and PiCarta using combinations of the following key words: stroke, cerebrovascular disorders, physical therapy, physiotherapy, occupational therapy, exercise therapy, rehabilitation, intensity, dose-response relationship, effectiveness, and randomized controlled trial. References presented in relevant publications were examined as well as abstracts in proceedings. Studies that satisfied the following selection criteria were included: (1) patients had a diagnosis of stroke; (2) effects of intensity of exercise training were investigated; and (3) design of the study was a randomized controlled trial (RCT). For each outcome measure, the estimated effect size (ES) and the summary effect size (SES) expressed in standard deviation units (SDU) were calculated for ADL, walking speed, and dexterity using fixed and random effect models. Correlation coefficients were calculated between observed individual effect sizes on ADL of each study, additional time spent on exercise training, and methodological quality. Cumulative meta-analyses (random effects model) adjusted for the difference in treatment intensity in each study was used for the trials evaluating the effects of AETT provided. Twenty of the 31 candidate studies, involving 2686 stroke patients, were included in the synthesis. The methodological quality ranged from 2 to 10 out of the maximum score of 14 points. The meta-analysis resulted in a small but statistically significant SES with regard to ADL measured at the end of the intervention phase. Further analysis showed a significant homogeneous SES for 17 studies that investigated effects of increased exercise intensity within the first 6 months after stroke. No significant SES was observed for the 3 studies conducted in the chronic phase. Cumulative meta-analysis strongly suggests that at least a 16-hour difference in treatment time between experimental and control groups provided in the first 6 months after stroke is needed to obtain significant differences in ADL. A significant SES supporting a higher intensity was also observed for instrumental ADL and walking speed, whereas no significant SES was found for dexterity. The results of the present research synthesis support the hypothesis that augmented exercise therapy has a small but favorable effect on ADL, particularly if therapy input is augmented at least 16 hours within the first 6 months after stroke. This meta-analysis also suggests that clinically relevant treatment effects may be achieved on instrumental ADL and gait speed.

The effects of exercise training on elderly persons with cognitive impairment and dementia: A meta-analysis

Heyn P, Abreu BC, Ottenbacher KJ. The effects of exercise training on elderly persons with cognitive impairment and dementia: a meta-analysis. Arch Phys Med Rehabil 2004;85:1694–704. Objective To determine by meta-analysis whether physical exercises are beneficial for people with dementia and related cognitive impairments. Data sources Published articles and nonpublished manuscripts from 1970 to 2003 were identified by using electronic and manual searches. Key search words included exercise, rehabilitation, activities of daily living, dementia, Alzheimer’s disease, aged, and geriatrics. Study selection Reviewed studies were limited to randomized trials evaluating exercise in persons 65 years of age or older with cognitive impairment. Studies included quantitative results (means, standard deviations, t tests, F tests) for physical fitness, physical functioning, cognition, or behavior outcomes. Data extraction One reviewer extracted data on study characteristics and findings. Selected articles were evaluated for methodologic quality by 2 raters. Data synthesis A total of 2020 subjects participated in the 30 trials that met the inclusion criteria. Summary effects were computed using a fixed effects (Hedge’s g i ) model. Significant summary effect sizes (ES) were found for strength (ES=.75; 95% confidence interval [CI], .58–.92), physical fitness (ES=.69; 95% CI, .58–.80), functional performance (ES=.59; 95% CI, .43–.76), cognitive performance (ES=.57; 95% CI, 0.43–1.17), and behavior (ES=.54; 95% CI, .36–.72). The overall mean ES between exercise and nonexercise groups for all outcomes was .62 (95% CI, .55–.70). Conclusions Exercise training increases fitness, physical function, cognitive function, and positive behavior in people with dementia and related cognitive impairments.

The acute effects of noninvasive ventilatory support during exercise on exercise endurance and dyspnea in patients with chronic obstructive pulmonary disease: a systematic review.

The objective of this study was to review studies systematically, in which the acute effects of noninvasive ventilatory support (NIVS) during exercise were evaluated in patients with chronic obstructive pulmonary disease (COPD). In addition, a quantitative analysis was performed on the effects of NIVS on exertional dyspnea and exercise endurance. Literature was searched in electronic databases, and by scanning lists of references of studies and abstract books of annual congresses of the American Thoracic Society and European Respiratory Society. Preliminary data of a study by our own group into the effects of NIVS on exercise endurance in patients with COPD were added. The systematic review was carried out on the basis of a validated methodological screening list. For the quantitative analysis, Glass delta of individual studies were pooled to aggregate a summary effect size. Fifteen studies were identified. Seven of these studies met the inclusion criteria, including a total of 65 patients with COPD. The methodological quality of the included studies varied from 31% to 54% of the maximum score of 13 points. Statistically significant summary effect sizes were found in the analysis of exertional dyspnea (P <.05) as well as in the analysis of exercise endurance (P <.001), indicating improvements in these outcomes in favor of NIVS. The present systematic review suggests that NIVS during exercise may acutely reduce exertional dyspnea and improve exercise endurance, in patients with COPD.

The effects of physical therapy in parkinson's disease: A research synthesis

Objective:To present a critical review and meta-analysis of studies evaluating the effects of physical therapy in patients suffering from Parkinson's disease (PD), in terms of neurologic signs, activities of daily living (ADLs), and walking ability. Data Sources:Articles published from 1966 to May 1999 were compiled by means of MEDLINE, Cochrane register of controlled trials, and CINAHL using combinations of the key words Parkinson's disease, exercise, exercise therapy, physical therapy, and group training. References presented in relevant publications were also examined. Articles written in English, German, or Dutch were included. Study Selection:Studies had to meet the following selection criteria: (1) patients with PD were included in the intervention study, (2) the effects of physical therapy (PT) were evaluated, (3) the study could be classified as true or quasi-experiment, and (4) the study was published in a journal or book. Data Extraction:Two reviewers assessed independently the methodologic quality of the data of each included study. One reviewer extracted relevant meta-analysis data. Data Synthesis:For each outcome measure the estimated effect size and the summary effect size (SES) were calculated, using fixed (ie, Hedges's g) and random effects models. The meta-analysis resulted in a significant homogeneous SES with regard to ADLs (.40; confidence interval [CI] = .17–.64) and stride length (.46; CI = .12–.82). The SES with regard to walking speed showed a significant heterogeneous SES, which remained significant after applying a random effects model (.49; CI = .21–.77). The SES with regard to neurologic signs was not significant (.22; CI = −.08 to .52). The small number of studies included and the shortcomings of the methodologic quality of these studies, however, bias the results of the present study. Conclusions:The results of the present research synthesis support the hypothesis that Parkinson patients benefit from PT added to their standard medication.

Effects of intensity of rehabilitation after stroke. A research synthesis.

A research synthesis was performed to (1) critically review controlled studies evaluating effects of different intensities of stroke rehabilitation in terms of disabilities and impairments and (2) quantify patterns by calculating summary effect sizes. The influences of organizational setting of rehabilitation management, blind recording, and amount of rehabilitation on the summary effect sizes were calculated. A Medline literature search was performed for a critical review of the literature. The internal and external validity of the studies was evaluated. In addition, a meta-analysis was performed by applying the fixed (Hedges's g) effects model. The effects of different intensities of rehabilitation were studied in nine controlled studies involving 1051 patients. Analysis of the methodological quality revealed scores varying from 14% to 47% of the maximum feasible score. Meta-analysis demonstrated a statistically significant summary effect size for activities of daily living (0.28 +/- 0.12). Lower summary effect sizes (0.19 +/- 0.17) were found for studies in which experimental and control groups were treated in the same setting compared with studies in which the two groups of patients were treated in different settings (0.40 +/- 0.19). Variables defined on a neuromuscular level (0.37 +/- 0.24) showed larger summary effect sizes than variables defined on a functional level (0.10 +/- 0.21). Weighting individual effect sizes for the difference in amount of rehabilitation between experimental and control groups resulted in larger summary effect sizes for activities of daily living and functional outcome parameters for studies that were not confounded by organizational setting. A small but statistically significant intensity-effect relationship in the rehabilitation of stroke patients was found. Insufficient contrast in the amount of rehabilitation between experimental and control conditions, organizational setting of rehabilitation management, lack of blinding procedures, and heterogeneity of patient characteristics were major confounding factors.