COPD: Bone Density (2008)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To evaluate the relationships between COPD, osteopoenia, osteoporosis, and disturbances in bone mass and density. 

Inclusion Criteria:
No inclusion criteria besides COPD was specified.
Exclusion Criteria:
No exclusion criteria were specified.
Description of Study Protocol:

Recruitment

Patients and controls were recruited from an outpatient clinic and hospital patient population.

Design:  Case-Control study

Blinding used (if applicable): Not applicable

Intervention (if applicable): Not applicable

Statistical Analysis

t-Student test, Kolmogorov-Smirnov test, Lilliefors test, Leven test, non-parametric tests, Kruskall-Wallis test, ANOVA, Pearson's test and chi-square test were reported.  Statistical significance was designated at p<0.05 and no other p values were presented in the rest of the paper.

Data Collection Summary:

Timing of Measurements

All measurements made and compared between cases and controls.

Dependent Variables

  • Spirometric evaluation
  • Bronchodilator response tests
  • Bone densitometry by DEXA

Independent Variables

  • COPD or healthy controls, duration of respiratory illness

Control Variables

  • Age and sex
  • Activity level
  • Smoking
  • Concurrent illnesses
  • Use of drugs
Description of Actual Data Sample:

Initial N: 77 subjects: 20 controls, 57 with COPD (19 with oral corticosteroid use, 14 with inhaled corticosteroid use)

Attrition (final N): as above

Age: COPD subjects age ranged 38-90 years, mean age = 64.3 years

Ethnicity: Not specified

Other relevant demographics:

Anthropometrics Mean age, weight, height, body surface area, and BMI were not significantly different between control and COPD groups.

Location: Lublin, Poland

 

Summary of Results:

 

Variables

Normal Osteopenia Osteoporosis
Percent all patients without COPD 45 30 25

Percent all patients with COPD

36 30 34

Percent all female patients without COPD

 50

33

17 

Percent all female patients with COPD 45 9 46
Percent all male patients without COPD 43 29 28
Percent all male patients with COPD 34 34 32

 

Other Findings

The mean values of bone mineral density, bone mineral content and T-score did not differ significantly between the groups.

Frequency of osteoporosis was much higher among patients with COPD, particularly in women (46%).

Bone mineral density decreased with age, but was lower with faster rate of loss in females than males and in subjects with COPD than without in both genders.

Author Conclusion:

The research confirmed the relationship between the patients' bone mass and density and their age, sex, weight, and body surface.  Osteoporosis frequency rate was much higher among patients with COPD, particularly women.  The following relationship was observed between the progression of the disease and the mass and mineral density of the bones:  the more advanced was the airflow obstruction, the lower were the osseous mass coefficients.  Forced expiratory volume during the first second and airflow obstruction reversibility rate determined by means of bronchodilator response also had a considerable influence on osseous mass coefficients.

Funding Source:
Reviewer Comments:

Cases and controls were not matched.  Inclusion/exclusion criteria not well defined.  Authors note that factors like cigarette smoking, physical inactivity, increased levels of TNF-alpha and other cytokines, glucocorticoid therapy in patients with COPD can lead to excessive decrease of bone mass, but they did not control for all of these variables.

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? No
  2.2. Were criteria applied equally to all study groups? No
  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.) Yes
  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.) Yes
  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? N/A
  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? N/A
  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? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  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? ???
  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? No
  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? No
  8.2. Were correct statistical tests used and assumptions of test not violated? ???
  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)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? ???
  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? N/A
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? No
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