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
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