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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Meta-analysis of walking for preservation of bone mineral density in postmenopausal women

M Martyn-St James and S Carroll.

Review published: 2008.

Link to full article: [Journal publisher]

CRD summary

The authors concluded that regular walking had no significant effect on spinal bone mineral density in postmenopausal women; there were significant positive effects on femoral neck bone mineral density. Most aspects of this review were well-conducted. Some caution may be required when interpreting the authors' conclusions, given the barely statistically significant intervention effect and limited quality of the included studies.

Authors' objectives

To evaluate the effects of prescribed walking programmes on hip and spine bone mineral density in postmenopausal women.

Searching

MEDLINE, EMBASE, Web of Science, SPORTDiscus, Evidence Based Medicine Reviews Multifile (EBMZ) and ProQuest were searched from inception to December 2006. Search terms were reported. Non English-language studies were eligible. Six specified peer-reviewed journals were handsearched. Reference lists of reviews and relevant publications were screened. Web searches were conducted. Peer-reviewed studies, abstracts, theses and dissertations were eligible.

Study selection

Randomised controlled trials (RCTs) and non-randomised controlled studies that evaluated walking as the sole exercise intervention in sedentary postmenopausal women were eligible for inclusion. Review outcomes were bone mineral density at the lumbar spine, femoral neck and total hip. Studies had to report bone mineral density outcomes either as absolute changes from baseline or follow-up values in areal bone mineral density (g/cm2)measured using radiographic techniques.

In the included studies, participants were mostly Caucasian or Japanese. Time since menopause varied (range approximately four to 20 years). All except one of the studies either excluded patients who took hormone replacement therapy or reported that no patient took this. All but one of the studies was either in non-smokers or smoking status was not reported. Walking interventions varied. Generally sessions lasted 20 to 60 minutes. Intensity varied from low intensity to brisk walking; in one study a graded treadmill was used. Some walking sessions were supervised and others were not. Nutritional supplements (calcium or isoflavone) were used in some studies. Half of the studies measured bone mineral density using dual X-ray absorptiometry (DXA) equipment; the other half used dual photon absorptiometry (DPA) equipment. Duration of interventions ranged from six to 24 months.

Two reviewers independently selected studies. There were no disagreements on inclusions.

Assessment of study quality

Validity was assessed using the Jadad criteria (randomisation, blinding and reporting of withdrawals). The maximum possible score was 5 points.

The authors did not state how many reviewers assessed validity.

Data extraction

Two reviewers independently extracted bone mineral density values and standard deviations (SD). Where studies had more than one walking intervention group, each walking intervention was treated separately and the number of patients in the control group divided equally between the comparisons.

Methods of synthesis

Pooled weighted mean differences (WMD) with 95% confidence intervals (CI) were calculated using a random-effects model if I2 was 50% or more; otherwise a fixed-effect model was used. Heterogeneity was assessed using the Q and the I2 statistics. Subgroup analysis was used to examine the influence of the method used to measure bone mineral density and nutritional supplements. Sensitivity analysis was used to examine the effect of study design (randomised or not) and high attrition rate (>30%). Publication bias was assessed using funnel plots.

Results of the review

Eight studies were included (n=427). These included five RCTs (n=335) and three non-randomised controlled studies (n=92). Jadad quality scores ranged from 1 to 3 out of 5. One study reported use of an adequate randomisation method. None reported participant blinding or adequate allocation concealment. Only two studies assessed compliance; rates were 77% and 85%.

There was no statistically significant difference between walking interventions and controls in lumbar spine bone mineral density (WMD 0.007 g/cm2, 95% CI -0.001 to 0.016, p=0.09). No significant heterogeneity was found. The increase in femoral neck bone mineral density in walking groups just reached statistical significance (WMD 0.014g/cm2, 95% CI 0.000 to 0.0028, p=0.05). Significant heterogeneity was found (I2=51.4%).

There was no statistically significant difference between walking interventions and controls in lumbar spine or femoral neck bone mineral density after excluding non-randomised studies, studies with high attrition rates and studies that used nutritional supplements, or when studies were grouped by methods used to measure bone mineral density.

The funnel plot for studies of lumbar spine bone mineral density was asymmetrical, which suggested potential for publication bias. The funnel plot of femoral neck bone mineral density was symmetrical.

Authors' conclusions

Regular walking had no significant effect on bone mineral density at the spine in postmenopausal women. There were significant positive effects on femoral neck bone mineral density.

CRD commentary

The review question was clearly stated and inclusion criteria were appropriately defined. Several relevant sources were searched and attempts were made to minimise publication and language biases. The potential for publication bias was assessed and some evidence was found. Appropriate methods were used to minimise reviewer error and bias during study selection and data extraction; it was unclear whether similar steps were taken in the assessment of validity. Validity was assessed and results were reported. Appropriate methods were used for the meta-analyses. Heterogeneity was assessed and various subgroup analyses were conducted. Although randomised and non-randomised studies were pooled in the main analyses, RCTs were subsequently analysed separately. Some limitations of the evidence were discussed. Results for femoral neck bone mineral density just reached statistical significance for all studies combined, but there was no significant difference when only RCTs were analysed and a more cautious conclusion about the effect of walking interventions on bone mineral density would seem more appropriate. This was generally a well-conducted review. Most aspects of the review were well conducted. Some caution may be required when interpreting the authors' conclusions, given the barely statistically significant intervention effect and limited quality of the included studies.

Implications of the review for practice and research

Practice: The authors stated that there was a need to revise recommendations about the effect of walking on bone mineral density in postmenopausal women. Combined walking and other exercise that provided adequate skeletal loading may be required to reduce the risk of fractures.

Research: The authors did not state any implications for research.

Funding

Not stated.

Bibliographic details

Martyn-St James M, Carroll S. Meta-analysis of walking for preservation of bone mineral density in postmenopausal women. Bone 2008; 43(3): 521-531. [PubMed: 18602880]

Indexing Status

Subject indexing assigned by NLM

MeSH

Aged; Bone Density; Bone Density Conservation Agents /therapeutic use; Bone and Bones; Exercise; Female; Femur Neck /pathology; Humans; Lumbar Vertebrae /pathology; Middle Aged; Models, Statistical; Osteoporosis, Postmenopausal /prevention & control; Postmenopause; Quality Control; Walking

AccessionNumber

12009101209

Database entry date

25/11/2009

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 18602880