Is Vitamin D Supplementation Effective for Low Back Pain?

BACKGROUND: Low back pain (LBP) is the leading cause of years lived with disability worldwide. Current intervention strategies are failing to reduce the enormous global burden of LBP and are prompting researchers to investigate alternative management strategies, such as vitamin D supplementation. Vitamin D supplementation appears to down regulate pro-inflammatory cytokines which lead to pain and up regulate anti-inflammatory cytokines that reduce inflammation. These mechanisms might explain the increasing interest in the use of vitamin D supplementation for LBP.

OBJECTIVES: To determine whether vitamin D supplementation improves pain more than a control intervention for individuals with LBP.

STUDY DESIGN: This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

METHODS: We performed searches in numerous electronic databases combining key words relating to “vitamin D” and “LBP” until March 2017. Studies were included if they investigated vitamin D supplementation in participants with LBP, provided there was a comparison intervention. There was no restriction on the type of LBP, the intervention parameters investigated, or the type of clinical trial (e.g., randomized, non-randomized). Two reviewers independently performed the selection of studies, extracted data, rated the methodological quality of the included studies, and evaluated the overall quality of the evidence using the Grading of Recommendations Assessment, Delevopment, and Evaulation (GRADE) approach.

RESULTS: After screening 3,534 articles, 8 clinical trials were included in this systematic review. There is very low quality evidence (based on the GRADE approach) that vitamin D supplementation is not more effective than any intervention (including placebo, no intervention, and other conservative/pharmacological interventions) (continuous pain measures [0-100]: mean difference [MD] = -2.65, 95% confidence interval [CI]: -10.42 to 5.12, P = 0.504, n = 5; self-reported reduction in pain: pooled odds ratio [OR] = 1.07, 95% CI: 0.35 to 3.26, P = 0.906, n = 5) or placebo/no intervention for individuals with LBP (continuous pain measures: MD = 1.29, 95% CI: -3.81 to 6.39, P = 0.620, n = 4; self-reported reduction in pain: pooled OR = 1.53, 95% CI: 0.38 to 6.20, P = 0.550, n = 4), where ‘n’ is the number of studies included in the meta-analysis. These results did not change when we stratified the meta-analyses by the type of vitamin supplementation (vitamin D3 vs. alfacalcidol) or the type of LBP (non-specific vs. LBP resulting from osteoporosis or vertebral fractures).

LIMITATIONS: The overall quality of evidence was “very low” due to the poor methodological quality and small sample sizes of the included studies.

CONCLUSIONS: Vitamin D supplementation is not more effective than placebo, no intervention, or other conservative/pharmacological interventions for LBP (based on very low quality evidence). These results are consistent, regardless of the type of LBP or vitamin D supplementation. Until well-designed and adequately powered clinical trials suggest otherwise, the prescription of vitamin D for LBP cannot be recommended.

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Osteoporosis Drugs Lower Fracture Risk, but Best One Unclear

Several medications are able to reduce fracture risk in individuals with bone density in the osteoporotic range and/or preexisting hip or vertebral fracture, according to a systematic review published online September 9 in the Annals of Internal Medicine. However, a paucity of comparative studies makes it difficult to determine the relative effectiveness of the medications.

Effective drugs include bisphosphonates, denosumab, teriparatide, and raloxifene, report Carolyn J. Crandall, MD, from the David Geffen School of Medicine at the University of California, Los Angeles, and colleagues.

Given the lack of head-to head trials, differences in adverse effect profiles may be key for physicians and patients when choosing which drug to use, the authors note.

The authors screened 52,000 titles and found very few head-to-head comparisons between different medications used to treat osteoporosis. The ongoing Vertebral Fracture Treatment Comparisons in Osteoporotic Women (VERO) study will be completed in 2016, however, and the resulting data should shed some light on the relative efficacy and safety of the different options.

On the basis of that trial and on the observational study data that are available, Dr. Crandall and colleagues estimate that bisphosphonates, denosumab, and teriparatide treatment result in a risk reduction for vertebral fractures of 0.40 to 0.60 relative to placebo. The relative risk reduction for nonvertebral fractures was 0.60 to 0.80. Raloxifene has only been demonstrated to reduce vertebral fractures.

In other words, they estimate 60 to 89 patients need to be treated with a bisphosphonate, denosumab, teriparatide, or raloxifene to prevent 1 vertebral fracture over the course of 1 to 3 years of treatment. Fifty to 60 patients need to be treated with a bisphosphonate, denosumab, or teriparatide to prevent a single nonvertebral fracture.

Adverse Event Profiles Differ

Dr. Crandall and colleagues note that atypical subtrochanteric femur fracture is a newly recognized adverse event of bisphosphonate use. The adverse event has not been detected in clinical trials, which are not powered to detect rare events, but 2 studies that used either meta-analyses or large safety databases put the hazard ratio for the serious adverse event at 1.70 and 4.51, respectively.

The more common adverse events, such as gastrointestinal effects, hot flashes, chills, and cardiovascular events, differ between agents, but no agent is without adverse effects.

Few Data for Older Patients

In an accompanying editorial, Heike A. Bischoff-Ferrari, MD, DrPH, from the University of Zurich and Otto Meyer, MD, from the City Hospital Waid in Zurich, Switzerland, point out that a major limitation in the systematic review is that it does not reflect data for women who are older than 80 years.

Approximately 75% of osteoporotic fractures occur in patients who are 65 years of age or older, and many of these patients are older than 80 years.

There is a major limitation in the systematic review, however: It does not reflect data for women who are older than 80 years. Approximately 75% of osteoporotic fractures occur in patients who are 65 years old or older, and many of these patients are older than 80 years.

The aging of the Western population has resulted in patients older than 80 years increasingly being included in clinical trials of pharmacologic treatments for the prevention of fractures. For example, the Hip Intervention Program trial of risedronate included women aged 70 to 79 years as well as a second group of women aged 80 years or older. Although risedronate was effective in the first group, it did not reduce hip fracture risk in women aged 80 years or older.

The Hip Intervention Program trial represents just 1 study of this vulnerable population. The results from other studies of older patients are not yet in. “Because these patients sustain most fragility fractures, their insufficient representation in current clinical trials of pharmacologic treatments against fractures warrants emphasis,” write Dr. Bischoff-Ferrari and Dr. Meyer.

This absence of data led Dr. Bischoff-Ferrari and Dr. Meyer to write that, “Although this is helpful information to guide clinicians and their patients, we believe that they should recognize that these conclusions may not apply to patients aged 75 years or older, and especially not to those aged 80 years or older with nonskeletal risk factors for falls. Such patients are insufficiently represented in the clinical trials of pharmacologic treatments for fracture prevention included in this careful evidence review.”