COPD: Bone Density (2008)

Citation:
 
Study Design:
Class:
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Quality Rating:
Research Purpose:

The purpose of this study was to evaluate stable COPD outpatients receiving regular therapy for osteoporosis by measuring their bone mineral density (BMD), to compare it with that of healthy controls of the same age group, in order to clarify whether the patients were suitable candidates for bone mass screening.

Inclusion Criteria:
  • Male COPD patients, diagnosed according to the American Thoracic Society criteria
  • Regularly followed by the outpatient clinic of the Chest Diseases Clinic
  • Nonsmoking volunteers of the same age range with normal pulmonary function served as controls

 

Exclusion Criteria:
  • Respiratory diseases other than COPD
  • Endocrine, metabolic, renal, hepatic, rheumatologic or bone disease, osteoporosis, malabsorption or alcoholism
  • Those who were immobilzed or using drugs related to bone metabolism
  • History of vertebral or femoral fractures
Description of Study Protocol:

Recruitment

Subjects were recruited from the outpatient clinic of the Chest Diseases Department, Adnan Menderes University School of Medicine, Aydia Turkey

Design:  Case-Control Study

Subjects and healthy controls were evaluated for patient characteristics including smoking history, medication information and body mass index (BMI). A dietary evaluation, pulmonary function tests and bone density measures were done.

Blinding used (if applicable): Not applicable

Intervention (if applicable):  Not applicable 

Statistical Analysis

  • Bone density parameters between the two groups were evaluated by the Student's t-test.
  • Pearson's correlation test was used to search for correlations between bone density parameters and other data.
  • Results were considered to be statistically significant if the P value was less than 0.05.
Data Collection Summary:

Timing of Measurements

Measurements were done at one time.

Dependent Variables

  • Pulmonary Functions (pulmonary function testing) 
  • Bone density (dual-energy X-ray absorptiometry at the lumbar spine, and the hip)

Independent Variables

  • COPD versus healthy controls

Control Variables

  • Controls were matched for male gender and age range
Description of Actual Data Sample:

Initial N: 28 subjects, 20 controls, all males

Attrition (final N): as above

Age: both groups mean 63 years

Ethnicity: not stated

Other relevant demographics:

Anthropometrics: There were no signficant differences between the 2 groups in terms of years of pack-years of smoking, BMI, lung functions, pH, PO2 and PCO2

Location: Aydin, Turkey 

Summary of Results:

Other Findings

There were no signficant differences between groups in dietary parameters, level of physical activity or BMI.

There were no signficant differences between the COPD patients and controls in BMD or in lumbar and femoral T scores.

Lumbar BMD was positively corelated with FEV1/FVC (r=0.377, P = 0.048) and femoral BMD was correlated with arterial blood pH (r=0.431, P =0.022).

There were no differences in the lumbar or femoral BMD between COPD patients who had used systemic corticosteroids during exacerbations and those who had not.

 

Author Conclusion:

The risk of osteoporosis is not increasd in appropriately treated patient with moderate-degree COPD, and there is no indication for bone mass screening in this group.

Funding Source:
Reviewer Comments:

Wide range of lung function in subjects - some at the severe category of COPD.

Possibility of Type II error - no statement of power analysis done.

All males studied.

Authors note that the study population consisted of moderate-degree, stable, well-nourished, and physically active COPD outpatients receiving regular treatment - findings may have limited generalizability.

Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) N/A
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) N/A
 
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? ???
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? ???
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? Yes
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? ???
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? ???
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? No
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes