Multiple sclerosis (MS) is an immune-mediated demyelination chronic disorder of the central nervous system that manifests in neurological disability of varying levels. Typical clinical features of MS include motor weakness, visual loss, spasticity, tremor, cognitive deficits and sensory loss or impairment. The pathogenesis of MS remains mostly undetermined, which contributes to the lack of efficacy of therapy for this condition.
Vitamin D deficiency is considered to be an environmental risk factor for MS (Rhead et al, 2016). Numerous studies have reported an association between low serum 25-hydroxyvitamin D (250HD) concentration and MS before and after the disease is triggered (Pierrot-Deseilligny and Souberbielle, 2017). Epidemiologic studies indicate that the prevalence of MS is minimal at the equator and greater at higher latitudes and tends to peak in areas with the lowest exposure to ultraviolet light (Correale et al, 2017). Furthermore, observational studies have implied that there is a correlation between the level of serum vitamin D and MS risk and disease activity (Sintzel et al, 2018). A reduced risk for developing MS and a reduction in relapse and disease activity in established MS are associated with higher levels of vitamin D (Runia et al, 2012). Due to the lack of consensus on the possible benefit of vitamin D for patients with MS, the available evidence requires closer consideration.
Objective/s
The objectives of Jagannath et al's (2018) updated Cochrane systematic review was to evaluate the benefit and safety of vitamin D supplementation for reducing disease activity in people with MS. The review collected primary outcome data on annualised relapse rate (ARR), changes in and the number of participants experiencing change in the expanded disability status scale (EDSS), mean change in magnetic resonance imaging (MRI) findings, time to first treated relapse, quality of life (QoL) and serious and minor adverse events (Jagannath et al, 2018). Secondary outcomes were hospitalisation rates, relapse-free participants, cognitive functions, physical symptoms, psychological symptoms, serum levels, bone density and immunological outcomes. All outcomes were elevated at 6 and 12 months and annually thereafter.
Methods
The authors searched for randomised controlled trials (RCTs) and quasi-RCTs in which vitamin D supplementation (alone or in combination with calcium) was compared to placebo, routine care or low doses of vitamin D. Studies that included participants over 18 years with a diagnosis of MS including subgroups were reviewed (Jagannath et al, 2018).
The reviewers searched nine electronic databases and trial registries for relevant trials up to October 2017. Papers were considered for this review irrespective of language, date and publication status. Selected studies were appraised for risk of bias using the Cochrane Handbook for Systematic Reviews of Interventions (Higgins et al, 2019). Quality of evidence was assessed using GRADE.
Results
Twelve studies with data available for 933 participants with MS from Iran, Europe, North America, Israel and Australia were included in this updated review (Jagannath et al, 2018). Eleven of the trials assessed vitamin D3. Five studies (417 participants) reported on the ARR (52 weeks after randomisation,) and there was no clear effect on ARR reduction in participants receiving disease-modifying medicines and vitamin D supplementation (low-quality evidence). Five trials (211 participants) reported on EDSS, and the findings indicated that vitamin D supplements were not effective in preventing worsening of disability (very low-quality evidence). In the four studies that reported on the effect of vitamin D to reduce MRI gadolinium-enhancing lesions, there was no effect noted compared with the placebo. The evidence was uncertain and limited in relation to vitamin D and health-related QoL, and adverse events were poorly reported. From all the included studies, none reported on cognitive function, psychological symptoms and hospitalisation. Vitamin D supplementation had an uncertain to no effect on bone density changes, immunological outcomes and fatigue.
Conclusions
From the review (Jagannath et al, 2018), the key point for nurses is that there is no evidence that vitamin D supplementation provides benefits for people with MS. Furthermore, it is difficult to determine a reliable risk profile for vitamin D supplementation due to poorly reported safety data. Clinicians should support further research to evaluate the benefit and safety of vitamin D supplementation for reducing disease activity in people living with MS.
Implications for practice
This review highlights that with the increased promotion of vitamin supplements for chronic disorders, nurses need to ensure that they are improving the health literacy of their patients by effectively communicating evidence-based practice to those living with MS.