NSUP: Vitamin D (2008)
Citation:
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To investigate whether vitamin D2 supplemention prevents fracture rate in senior citizens living in institutional care.
Inclusion Criteria:
All residents living in nursing homes, residential homes and sheltered housing.
Exclusion Criteria:
- Already taking 400 IU or more per day of vitamin D supplements
- Contraindications to vitamin D supplementation.
Description of Study Protocol:
- Recruitment: 314 care homes in the South Wales, UK, that agreed to participate in the study
- Design: Three-year study randomly assigning study participants into two groups of vitamin D2 supplementation or placebo
- Blinding: Nurse, participants and analysts were blinded to allocation
- Intervention: Two 1.25-mg vitamin D2 tablets (ergocalciferol) three times per year (100,000 IU every four months) for three years
- Statistical analysis: Data were analyzed using Kaplan-Meier (time to fracture) and Cox regression.
Data Collection Summary:
Timing of Measurements
Data collected from home care visits with a research nurse.
Dependent Variables
- Incidence of first fracture
- Incidence of hip fracture
- Fractures at a common osteoporotic sites (hip, wrist, forearem or vertebrae)
- Mortality rates.
Independent Variables
Vitamin D2 supplement
Control Variables
Institutionalized setting.
Description of Actual Data Sample:
- Initial N: 3,440 (2,624 women, 816 men)
- Attrition (final N): 1,038
- Age: 62 to 107 years of age
- Ethnicity: Undisclosed.
Anthropometrics and Demographics
Intervention | Control | Combined | |
Number |
1,725
|
1,715
|
3,440
|
Mean Age, Years (SD) |
84 (7.61)
|
84 (7.43)
|
84 (7.53)
|
Age Range |
65-105
|
62-107
|
62-107
|
Women |
1,314 (76.2%)
|
1.312 (76.5%)
|
2,626 (76.3%)
|
Residential Home |
38%
|
37%
|
38%
|
Nursing or Dual-Registered Home |
55%
|
56%
|
55%
|
Sheltered Accomodation |
|
|
7%
|
Location:
South Wales, UK.
Summary of Results:
Intervention | Control | Combined | ||
First Fractures | All sites |
205
|
218
|
423
|
Hip/wrist/forearm/vertebrae |
143
|
135
|
278
|
|
Hip/wrist/forearm |
140
|
126
|
266
|
|
Hip |
112
|
104
|
216
|
|
Other fractures |
62
|
83
|
145
|
|
All Fractures | All sites |
243
|
268
|
511
|
Hip/wrist/forearm/vertebrae |
164
|
163
|
327
|
|
Hip/wrist/forearm |
160
|
151
|
311
|
|
Hip |
127
|
126
|
253
|
|
Other fractures |
79
|
105
|
184
|
|
Deaths |
947
|
953
|
190
|
- There was no significance difference in fractures between the intervention and placebo groups: Vitamin D2 intervention, 205 first fractures, 2,846 volunteer follow-up (7.15% annual incidence); placebo, 218 first fractures , 2,860 volunteer follow-up (7.6% annual incidence)
- The hazard ratio for intervention compared with control was 0.95 (95% CI: 0.79-1.15; P>0.05)
- RN reported 80% adherence among volunteers
- Subset of 102 volunteers who underwent bloodwork:
- Mean serum 25(OH)D was 80.1nmol per L for intervention and 54.0nmol per L for placebo (sex- and age-adjusted 23.3nmol per L differences between groups)
- Mean PTH levels were 5.00pmol per L in the intervention and 6.65pmol per L in the control group (sex- and age-adjusted 1.42pmol per L).
Author Conclusion:
- Supplementation with 2.5mg (100,000 IU) of vitamin D2 every four months was not found to signficantly reduce fractures in elderly institutional care residents
- There is a need for more research in this area
- Vitamin D supplementation cannot be advocated as a public health approach to fracture prevention in home-care populations.
Funding Source:
Government: | Wales Office for Research and Development for Health and Social Care |
Reviewer Comments:
Author was thorough in stating bias and limitations of the study.
Quality Criteria Checklist: Primary Research
|
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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) | Yes | |
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) | Yes | |
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? | Yes | |
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? | Yes | |
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.) | 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? | 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? | 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? | N/A | |
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? | N/A | |
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? | Yes | |
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? | 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)? | Yes | |
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 | |