Statins have demonstrated their efficacy both in the prevention of cardiovascular mortality and its overall reduction.1 As a consequence, the number of patients receiving statin therapy has grown substantially and continues to increase. However, nearly 15%–30% of them will develop musculoskeletal pain (MSP) as the major adverse effect, which often leads to their discontinuing the treatment.2 The mechanism of the production of the pain is unknown and, potential factors include genetic predisposition, a possible mitochondrial dysfunction, a dysfunction involving coenzyme Q synthesis and/or cholesterol).3

Recent studies have suggested that vitamin D deficiency would be associated with MSP induced by statins and, that this could be reversible with vitamin D supplementation and the subsequent normalization of serum 25-hydroxyvitamin d (25OHD) levels.4,5

We performed the present systematic review of the literature for the purpose of determining whether serum 25OHD levels were associated or not with a higher prevalence of MSP related to the intake of statins.

The combined search identified 127 studies, 119 of which were excluded as they did not meet the inclusion criteria, and another 5 were ruled out as they were duplicates. Finally, 3 studies were included (Fig. 1): 1 of which was a SR, by Michalska-Kasiczak et al.,2 that contained 7 studies,1,7–12 as well as, another 2 that were cohort studies, which had been published more recently, Mergenhagen et al.13 and Morioka et al.14

Fig. 1.

Flow chart. SR, systemic review.

(0.1MB).

With regard to quality, the SR is acceptable (SIGN), as are the cohort studies (NOS 6–7) (Table 1).

The total population of the studies was 3927 patients, 1038 of whom (26.43%) had MSP, whereas the rest, 2889 (73.53%), were asymptomatic. The mean age of the patients was 61.7years, and ranged between 58 and 69years. There were 1026 women and 1527 men; there were no population-based data from the 3 studies.1,7,12

The drug most widely used was simvastatin2,12,13; it was followed in frequency by atorvastatin,2,12 pravastatina,2,8 and rosuvastatina.1,2 The doses used and the duration of the treatment were specified in only 1 of the cohort studies,13 in which simvastatin was employed at 80mg/day.

With respect to cointerventions, the authors of a single study,9 mention the utilization of other drugs like niacin, fenofibrate, diltiazem and verapamil.

In the SR2 (which included 7 studies; n=2420 patients) 27.5% patients had MSP, probably related to the intake of statins. The comparison of the mean serum levels of 25OHD in patients with MSP and asymptomatic patients, there was a mean of 28.4ng/mL in the first group vs 34.8ng/mL in the asymptomatic group. The weighted mean difference was: −9.41ng/mL (−10.17 to −8.64), with an elevated heterogeneity test (I2=94%; P=.00001).

In the study by Mergenhagen et al.13 (n=450), 11.1% of the patients had MSP. In the comparison of the mean serum 25OHD level in patients with MSP and those who were asymptomatic, there was a mean of 26.2ng/mL in the group with pain vs 36.3ng/mL in the asymptomatic patients, with a mean difference of 10ng/mL (P=.0003).

Finally, in the report by Morioka et al.14 (n=5907), 1057 (18%) of whom received statins, and 30.5% of this group, had MSP. Of these symptomatic patients, 43.8% (33.5%–54.6%) had 25OHD <15ng/mL vs 28% (23.4%–33.2%) who had levels >15ng/mL (P=.01).

These authors calculate the odds ratio (OR) of patients who are taking statins of developing MSP: if the 25OHD level is <15ng/mL, the OR=1.90 (1.18–3.05; P=.01), and if the 25OHD level is >15ng/mL, the OR=0.91 (0.71–1.16; P=.43) (Table 2).

The present systemic review suggests the existence of an association between vitamin D deficiency and MSP. Therefore, about 1 out of every 4 patients who were receiving statins in the present work, will manifest MSP. In this respect, the definition of MSP related to statins is somewhat confusing and quite vague,15 as there is no internationally standardized classification.16 Its clinical form encompasses, from simple myalgia or muscle weakness, and even rhabdomyolysis. Thus, its most frequently observed presentation is muscle pain that is not associated with an elevation in creatine phosphokinase.16,17 Likewise, it is well-known that reduced serum vitamin D levels are also the cause of generalized MSP,18 and possibly, the presence of vitamin D receptor (VDR) in muscle cells supports this principle.19 The relationship between serum 25OHD levels <30ng/mL and MSP associated with statins has been reported in certain uncontrolled series.8,20 Although, in a speculative manner, it has been estimated that the mechanism of interaction between MSP and statins and vitamin D deficiency could have a relationship with the activation of cytochromes CYP3A4, CYP2B6 and CYP2C9 in hepatocytes.3 Thus, vitamin D is an activator of these cytochromes, which, in turn, are responsible for metabolization of different statins, especially the lipophilic type (atorvastatin, simvastatin, lovastatin, fluvastatin and pravastatin).3,21 Their deficiency could explain a prolongation of the half-life of these drugs and their possible toxicity, resulting in MSP. The muscle fibers affected would be type II, which are also implicated in the myalgia caused by alcohol.22 Moreover, it is suggested that low vitamin D levels could reduce the transcriptional gene linked to VDR, decreasing the synthesis of proteins to repair the t-tubular system and prevent the subsarcolemmal rupture of those fibers.22 The combination of these 2 causal factors, the vitamin D deficiency and statins, would potentiate the involvement in type II muscle fibers, favoring the development of pain. This symptomatology appears to extend even to patients who receive statins on alternate days. Thus, the study of Minissian et al.23 demonstrated that patients with MSP caused by statins, who also received treatment on alternate days for intolerance to these drugs, had significantly decreased serum vitamin D levels when compared with those patients who were tolerant to the daily therapies. In contrast, studies like those of Eisen et al.,11 Kurnik et al.,24 and Backes et al.,10 found no connection among serum vitamin D levels and risk of MSP in patients receiving statins. Possibly, this divergence corresponds to differences in the type of population studied, ethnic groups, type and dose of statins employed or the nutritional status of the patients, etc. Once again, in none of these studies is the season of the year mentioned or are the methods used to assess serum 25OHD levels. In this respect, it is important to point out that vitamin D level deficiency (<30ng/mL or 75nmol/L)25,26 is a prevalent condition in different populations and regions of the world.27–29 Moreover, this situation is becoming more extended and more profound in recent years.30 For this reason, it is appropriate to mention, although it is not within the scope of this analysis, that uncontrolled studies have evaluated the response of patients with MSP due to statins to vitamin D supplementation, with encouraging results.4,5,8

This review has certain limitations: limitations inherent in the type of design and the biases of the studies included (retrospective designs, duration of the registry of inaccurate data, etc.). Likewise, there is little information concerning the types, doses and duration of statin therapy on the part of the patients, and too few references on the presence of comorbidities and/or cointerventions. One particularity to be taken into account is the updated definition of statin-induced MSP, which, in our opinion, is very vague and can lead to confusion. Finally, we understand that it is very important to define the methodology for measuring vitamin D, as well as the season of the year in which the sample is collected and is analyzed, and its evaluation according to age group.

We can conclude that the available evidence (a systematic review and 2 cohort studies) shows a prevalence of MSP associated with statins that ranges between 11% and 30%. There is also a significant association between decreased serum 25OHD levels, and a higher prevalence of statin-related MSP.

Well-designed, long-term, prospective studies are needed to confirm these results.

The authors declare they have no conflict of interest.