Interventions to increase physical activity among healthy adults: meta-analysis of outcomes.

OBJECTIVES: We conducted a meta-analysis summarizing the effects of interventions designed to increase physical activity among healthy adults. METHODS: Our comprehensive searches located 358 reports eligible for inclusion. We used random-effects analyses to synthesize data, and we used meta-analytic analogues of regression and analysis of variance to examine potential moderator variables. We also explored moderator variable robustness and publication bias. RESULTS: We computed meta-analytic results from studies comprising 99 011 participants. The overall mean effect size for comparisons of treatment groups versus control groups was 0.19 (higher mean for treatment participants than for control participants). This effect size is consistent with a mean difference of 496 ambulatory steps per day between treatment and control participants. Exploratory moderator analyses suggested that the characteristics of the most effective interventions were behavioral interventions instead of cognitive interventions, face-to-face delivery versus mediated interventions (e.g., via telephone or mail), and targeting individuals instead of communities. Participant characteristics were unrelated to physical activity effect sizes. Substantial between-studies heterogeneity remained beyond individual moderators. CONCLUSIONS: Interventions designed to increase physical activity were modestly effective. Interventions to increase activity should emphasize behavioral strategies over cognitive strategies.

Random-effects meta-analysis of correlations: Monte Carlo evaluation of mean estimators.

Several authors have cautioned against using Fisher's z-transformation in random-effects meta-analysis of correlations, which seems to perform poorly in some situations, especially with substantial inter-study heterogeneity. Attributing this performance largely to the direct z-to-r transformation (DZRT) of Fisher z results (e.g. point estimate of mean correlation), in a previous paper Hafdahl (2009) proposed point and interval estimators of the mean Pearson r correlation that instead use an integral z-to-r transformation (IZRT). The present Monte Carlo study of these IZRT Fisher z estimators includes comparisons with their DZRT counterparts and with estimators based on Pearson r correlations. The IZRT point estimator was usually more accurate and efficient than its DZRT counterpart and comparable to the two Pearson r point estimators - better in some conditions but worse in others. Coverage probability for the IZRT confidence intervals (CIs) was often near nominal, much better than for the DZRT CIs, and comparable to coverage for the Pearson r CIs; every approach's CI fell markedly below nominal in some conditions. The IZRT estimators contradict warnings about Fisher z estimators' poor performance. Recommendations for practising research synthesists are offered, and an Appendix provides computing code to implement the IZRT as in the real-data example.

Meta-analysis of correlations revisited: attempted replication and extension of Field's (2001) simulation studies.

In 2 Monte Carlo studies of fixed- and random-effects meta-analysis for correlations, A. P. Field (2001) ostensibly evaluated Hedges-Olkin-Vevea Fisher-z and Schmidt-Hunter Pearson-r estimators and tests in 120 conditions. Some authors have cited those results as evidence not to meta-analyze Fisher-z correlations, especially with heterogeneous correlation parameters. The present attempt to replicate Field's simulations included comparisons with analytic values as well as results for efficiency and confidence-interval coverage. Field's results under homogeneity were mostly replicable, but those under heterogeneity were not: The latter exhibited up to over .17 more bias than ours and, for tests of the mean correlation and homogeneity, respectively, nonnull rejection rates up to .60 lower and .65 higher. Changes to Field's observations and conclusions are recommended, and practical guidance is offered regarding simulation evidence and choices among methods. Most cautions about poor performance of Fisher-z methods are largely unfounded, especially with a more appropriate z-to-r transformation. The Appendix gives a computer program for obtaining Pearson-r moments from a normal Fisher-z distribution, which is used to demonstrate distortion due to direct z-to-r transformation of a mean Fisher-z correlation.

Meta-analysis of quality-of-life outcomes from physical activity interventions.

BACKGROUND: Interventions to increase physical activity among adults with chronic illness are intended to improve quality of life and reduce disease complications or slow disease progression. OBJECTIVE: The aim of this study was to integrate quality-of-life outcomes from primary research studies testing interventions to increase physical activity among adults with chronic illness. METHODS: Extensive literature searching strategies were used to locate published and unpublished primary research testing physical activity interventions. Results were coded for studies that had at least 5 participants with chronic illness. Fixed- and random-effects meta-analytic procedures included moderator analyses. RESULTS: Eighty-five samples from 66 reports with 7,291 subjects were synthesized. The mean quality-of-life effect size for two-group comparisons (treatment vs. control) was.11 (higher mean quality-of-life scores for treatment subjects than for control subjects). The treatment group pre-post comparison effect size was.27 for quality of life. Heterogeneity was modest in two-group comparisons. Most design and sample attributes were unrelated to intervention effects on quality of life. Studies that exclusively used supervised center-based exercise reported larger quality-of-life improvements than did studies that included any educational/motivational content. Effect sizes were larger among unpublished and unfunded studies. The effect size for physical activity did not predict the quality-of-life effect size. DISCUSSION: Subjects experience improved quality of life from exposure to interventions designed to increase physical activity, despite considerable heterogeneity in the magnitude of the effect. Future primary research should include quality-of-life outcomes so that patterns of relationships among variables can be explored further.

Improved Fisher z estimators for univariate random-effects meta-analysis of correlations.

Several authors have studied or used the following estimation strategy for meta-analysing correlations: obtain a point estimate or confidence interval for the mean Fisher z correlation, and transform this estimate to the Pearson r metric. Using the relationship between Fisher z and Pearson r random variables, I demonstrate the potential discrepancy induced by directly z-to-r transforming a mean correlation parameter. Point and interval estimators based on an alternative integral z-to-r transformation are proposed. Analytic expressions for the expectation and variance of certain meta-analytic point estimators are also provided, as are selected moments of correlation parameters; numerical examples are included. In an application of these analytic results, the proposed point estimator outperformed its usual direct z-to-r counterpart and compared favourably with an estimator based on Pearson r correlations. Practical implications, extensions of the proposed estimators, and uses for the analytic results are discussed.

Article alert: 200 items from 2014, grouped and indexed.

This ninth Article Alert installment's print component presents 200 methodological articles about research synthesis published in 2014, all grouped by type of contribution and assigned descriptive keywords. More than 5300 articles, book chapters, and other types of work from 2004 to 2008 and 2014 have been added to the archive component since the eighth installment. The online Supporting Information provides this and all previous installments' print- and archive-component records, most with a DOI name or other online identifier. In building the parent bibliographic compilation, more effort has been devoted recently to shorter pieces such as editorial material.

Physical activity interventions among adults with arthritis: meta-analysis of outcomes.

OBJECTIVE: Due to reduced physical activity, adults with arthritis experience significant disability and comorbidities including cardiovascular disease. This meta-analytic review integrates results from primary research studies testing interventions to increase physical activity in arthritis patients. METHODS: Extensive literature searching strategies were employed to locate published and unpublished empirical studies testing physical activity interventions. Results were coded for studies that had at least 5 participants. Effect sizes (ESs) were calculated for measures of physical activity, pain, and objective and subjective measures of functional ability. RESULTS: Twenty-eight research studies with 4111 subjects were synthesized. The mean ES for 2-group comparisons (treatment versus control) was 0.69 for physical activity, 0.21 for pain, 0.49 for objectively measured function, and 0.14 for subjectively measured function. This average effect on subjective function is consistent with a Health Assessment Questionnaire mean of 0.64 for treatment subjects as compared with 0.70 for control subjects. For pain assessed using the 0 to 10 visual analog scale, the average effect amounts to a mean of 3.78 for treatment subjects versus 4.33 for control subjects. Control group subjects experienced statistically significant improvements in pain and, to a lesser extent, objectively measured functional ability during study participation. CONCLUSIONS: Physical activity interventions resulted in moderate positive effects on physical activity behavior and small positive effects on pain and physical function outcomes. Future research should examine specific intervention characteristics that result in optimal results, such as frequency, type, and intensity of exercise.

Meta-analysis of patient education interventions to increase physical activity among chronically ill adults.

OBJECTIVE: This meta-analysis integrates primary research testing the effect of patient education to increase physical activity (PA) on behavior outcomes among adults with diverse chronic illnesses. METHODS: Extensive literature searching strategies located published and unpublished intervention studies that measured PA behavior outcomes. Primary study results were coded. Fixed- and random-effects meta-analytic procedures included moderator analyses. RESULTS: Data were synthesized across 22,527 subjects from 213 samples in 163 reports. The overall mean weighted effect size for two-group comparisons was 0.45 (higher mean for treatment than control). This effect size is consistent with a difference of 48 min of PA per week or 945 steps per day. Preliminary moderator analyses suggest interventions were most effective when they targeted only PA behavior, used behavioral strategies (versus cognitive strategies), and encouraged PA self-monitoring. Differences among chronic illnesses were documented. Individual strategies unrelated to PA outcomes included supervised exercise sessions, exercise prescription, fitness testing, goal setting, contracting, problem solving, barriers management, and stimulus/cues. PA outcomes were unrelated to gender, age, ethnicity, or socioeconomic distribution among samples. CONCLUSION: These findings suggest that some patient education interventions to increase PA are effective, despite considerable heterogeneity in the magnitude of intervention effect. PRACTICE IMPLICATIONS: Moderator analyses are preliminary and provide suggestive evidence for further testing of interventions to inform practice.

Meta-analysis of health behavior change interventions in type 1 diabetes.

OBJECTIVES: To meta-analyze research testing interventions to improve health behaviors including exercise among adults with type 1 diabetes. METHODS: Multiple literature-searching strategies identified published and unpublished studies reporting glycated hemoglobin outcomes. Fixed- and random-effects meta-analyses included moderator effects. RESULTS: Data were synthesized across 1435 subjects. The overall effect size was 0.26. This translates into a reduction of 0.33 in mean HbA1c levels between treatment (8.47%) and control (8.80%) groups. Effect sizes were larger with more females, lower body mass index, higher baseline HbA1c, and interventions targeting multiple behaviors. CONCLUSIONS: Behavior change interventions improve metabolic control in type 1 diabetes.

Article alerts: Items from 2013.

This eighth installment of 'Article Alerts' includes a print component with 200 methodological articles about research synthesis published in 2013. Since the preceding installment, more than 3400 articles, dissertations, book chapters, and other types of work in this methodological domain have been added to the archive component, all from 2009 to 2013. The online Supporting Information now includes over half of the parent compilation's more than 26 000 records: 1000 from the print component and more than 13 000 from the archive component. Current online addresses for similar bibliographic resources are provided.

Article Alerts: Items from 2012.

This seventh installment of "Article Alerts" includes a print component with 200 methodological articles about research synthesis published in 2012. More than 800 dissertations and theses have been added to the archive component since the preceding installment. Also since that installment, the parent compilation from which the print and archive components are built has more than doubled and now contains nearly 26 000 items.

Meta-analysis of the effect of exercise interventions on fitness outcomes among adults with type 1 and type 2 diabetes.

This review applied meta-analytic procedures to integrate primary research that examined exercise fitness outcomes among adults with type 1 or type 2 diabetes. We used extensive literature searching strategies to locate published and unpublished intervention studies that tested exercise interventions. We conducted meta-analytic procedures using both fixed- and random-effects models. Analyses were conducted separately for type 1 and type 2 diabetes and separately for two-group and single-group data under two assumptions about pre-post fitness outcomes association: no association and a strong positive association (0.80). Codable data were extracted from 35 reports with 1074 subjects. The type 1 diabetes overall weighted mean effect size for two-group comparisons was 0.65. For treatment group pretest versus post-test, the effect was 0.62. The effect size among adults with type 2 diabetes for two-group comparisons was 0.35. The treatment group pretest versus post-test comparison effect was 0.37. Effect sizes among control group participants were not statistically different from 0. For type 2 diabetes two-group comparisons, larger effect sizes were associated with exercise prescription, fitness testing, supervised exercise, group sessions, and recommendations for longer duration exercise sessions. HbA1c, age, body mass index, and gender distribution were unrelated to fitness outcomes.

Article Alerts: items from 2011, Part II.

This sixth 'Article Alerts' installment's print component includes 100 methodological articles about research synthesis published in 2011. Since the preceding installment, more than 2100 items have been added to the archive component, mostly from 2010 to 2011, and identifying codes have been added to more than 2400 previous archive items. The associated online library, available for free via CiteULike, now contains 2000 items from this feature.

Insulin Sensitivity Following Exercise Interventions: Systematic Review and Meta-Analysis of Outcomes Among Healthy Adults.

OBJECTIVE: Although exercise can improve insulin sensitivity, no adequate synthesis exists of exercise intervention studies with regard to their effect on insulin sensitivity. This comprehensive meta-analysis synthesized the insulin sensitivity outcomes of supervised exercise interventions. METHOD: Extensive literature searching located published and unpublished intervention studies that measured insulin sensitivity outcomes. Eligible studies tested supervised exercise interventions among healthy adults. Primary study characteristics and results were coded. Random-effects meta-analyses of standardized mean differences included moderator analyses. RESULTS: Data were synthesized across 2509 subjects (115 samples, 78 reports). The overall mean effect size for 2-group postintervention comparisons was 0.38 (95% confidence interval [CI] = 0.25-0.51, I (2) = 0%) and for 2-group pre-post comparisons was 0.43 (95% CI = 0.30-0.56, I (2) = 52%; higher mean insulin sensitivity for treatment than control subjects). The postintervention mean of 0.38 is consistent with treatment subjects ending studies with a mean fasting insulin of 6.8 mU/L if control participants' mean fasting insulin were 7.9 mU/L. Exploratory moderator analyses did not document different insulin sensitivity effect sizes across intervention characteristics or sample attributes. CONCLUSION: This study documented that exercise is a valuable primary care and community health strategy for healthy adults to improve insulin sensitivity and lower the risk for diabetes conferred by insulin resistance.

Article Alerts: Items from 2011, Part I.

The print component of this fifth 'Article Alerts' installment comprises 100 articles published in 2011. Since the preceding installment, more than 1,100 items disseminated before 1994 have been added to the archive component. To improve access, searching, and other aspects of users' experience, items from the print and archive components are being added to an online library. Copyright © 2012 John Wiley & Sons, Ltd.

Article alerts: items from 2010, part I.

This third installment of the 'Article Alerts' feature section highlights 100 articles published in 2010 for the print component. More than 400 books and chapters and more than 100 dissertations and theses were added to the archive component since the last installment. Many items in the online supplemental material now include an identifier to facilitate online access. Copyright © 2011 John Wiley & Sons, Ltd.

Article Alerts: items from 2010, Part II.

The print component of this fourth 'Article Alerts' installment comprises 100 articles published in 2010. More than 2500 items have been added to the archive component since the preceding installment. Of these new archive items, more than 1500 were disseminated in 2009; the remainder, between 1994 and 1998, inclusive. Copyright © 2012 John Wiley & Sons, Ltd.

Article alerts: Introduction and items from 2009, part I.

This 'Article Alerts' feature is intended to apprise readers of recent methodological work in research synthesis and compile previous such contributions from various outlets. In this first installment we introduce the feature by commenting on its main aims and distinguishing between the print and archive versions. The feature's content and process are also described, including encouragement of interactive contributions from readers. The current installment's 100 items, a subset of relevant work published in 2009, are categorized by type of contribution and supplemented with suggested keywords. Copyright © 2010 John Wiley & Sons, Ltd.

Article alerts: Items from 2009, Part II.

This second installment of the 'Article Alerts' feature section more than doubles the collection's number of items. The print and archive versions now include 200 and 2579 items, respectively. Remarks are offered on inclusion criteria, anticipated growth of the archive version, and a related resource. Copyright 2011 John Wiley & Sons, Ltd.