EAL

COPD: Bone Density (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The primary objective of this study was to determine the prevalence of vertebral fractures among patients with COPD admitted to acute care compared with a gender- and age-matched control group. Secondary objectives were to determine the relationship between vertebral fractures and measures of lung function and the extent to which those with vertebral fractures received treatment for osteoporosis.

Inclusion Criteria:

Age 50 or older
Lateral chest x-ray taken during the index admission was available
Controls were selected from all those admitted over age 50 without diagnosis of COPD or asthma; one chart was randomly selected from every 20 successive medical admissions and reviewed for inclusion/exclusion criteria

Exclusion Criteria:

Excluded if chest x-ray was prompted by physical trauma and if they had known or suspected malignancy
Controls meeting inclusion criteria were excluded if they could not be matched within 5 years to a COPD patient

Description of Study Protocol:

Recruitment

Subjects were identified by chart reviews from an acute care hospital in Hamilton, Ontario from January 1, 1999 to December 31, 1999.

Design: Case-Control Study

Blinding used (if applicable): not applicable

Intervention (if applicable): not applicable

Statistical Analysis

Reliability of radiologic assessments examined
McNemar test for matched pairs was used to test for associations between case-control status and fracture status
Multivariate conditional logistic regression models were also used to identify risk factors for fractures as well as to examine whether there were subgroups of patients for whom the association between case-control status and fracture status was different
Simple linear regression was used to examine the relationship between vertebral fracture status and measures of lung function
Differences in the distribution of duration of hospitalization were assessed using Cox regression models

Data Collection Summary:

Timing of Measurements

Measurements made between cases and controls and compared.

Dependent Variables

Chest radiographs were interpreted by 2 radiologists who defined and graded vertebral fractures using Genant's method
Pulmonary function: forced expiratory volume, forced vital capacity
Osteoporosis treatment: receiving 1 or more of the following: calcium with or without vitamin D, hormone replacement therapy, raloxifene, bisphosphonates, and calcitonin

Independent Variables

Admitting diagnosis: COPD or healthy controls

Control Variables

Age and sex
Height and weight
Medications taken or prescribed at discharge were recorded from charts

Description of Actual Data Sample:

Initial N: 331 charts were available; after removing exclusions, 143 patients remained. After appropriate matching, 127 cases with COPD, 127 controls remained (49.6% men).

Attrition (final N): as above

Age: mean age cases and controls: 71.6 ± 9.7 years

Ethnicity: not mentioned

Other relevant demographics:

Anthropometrics: Controls were gender- and age-matched

Location: Ontario, Canada

Summary of Results:

Other Findings

Overall prevalence of at least 1 vertebral fracture was found to be 34/127 (26.8%) in the COPD patients compared with 30/127 (23.6%) in controls (P = 0.556).

A significantly greater proportion of COPD patients had at least 1 severe vertebral fracture (odds ratio = 3.75, 95% confidence interval = 1.24 to 11.3), P = 0.019.

There were no significant differences in the proportion of mild (P = 0.538) or moderate (P = 0.258) grade vertebral fractures between cases and controls.

Review of hospital chest X-ray reports indicated that only 12 of 64 (18.8%) patients with vertebral fractures identified by the study radiologists actually had a vertebral fracture noted in the report.

The proportion of COPD patients with vertebral fractures who were discharged on osteoporosis therapy was 5/27 (18.5%).

There was a suggestion of lower lung function, as measured by forced vital capacity, in patients with severe vertebral fractures (P = 0.067).

There was no significant association between oral corticosteroid use at index hospital admission and vertebral fracture status (odds ratio = 1.29, 95% CI: 0.43 to 3.85).

Similarly, there was no association between inhaled steroid use and vertebral fracture status (odds ratio = 2.31, 95% CI: 0.47 to 11.36).

Author Conclusion:

We found a 4-fold higher prevalence of severe vertebral fractures among COPD patients compared with controls. These data indicate that there is an increased proportion of COPD patients with severe vertebral fracture, and documentation and treatment of osteoporosis in acute care COPD patients is low. Therefore, there is a need to target this high-risk group for osteoporosis screening and potential clinical management.

Funding Source:

Reviewer Comments:

Authors note limitations of

not controlling for certain potential confounding variables (such as serum testosterone levels)
the possibility of underestimating the number and severity of vertebral fractures
sample size decreased due to restrictions of matching, limiting generalizability
did not conduct outpatient investigation of past use and total cumulative use of oral and inhaled corticosteroids, steroid use at admission may be a biased estimate of history of steroid use

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?	Yes
	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.)	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?	Yes
	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?	???
	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?		Yes
	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)?	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?	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