Abstract
Statin is a group of medication that have widely been used. Its muscle side effects can be divided into 2 groups: 1) self-limited statin associated muscle problems (e.g. myalgia, hyperCKemia, rhabdomyolysis) and 2) statin induced necrotizing autoimmune myopathy (SINAM). Unlike the other group, patients with SINAM require steroid and/or immunosuppressive drugs. Studies, especially in the United States, have founded that anti-HMGCR autoimmune myopathy, which can occur in both patients who take statin and statin naïve patients, is associated with HLA-DRB1*11:01, which can be found in up to 70% of patients. Interestingly, subgroup analysis from a study in Japan shows the association between SINAM and HLA DRB1*08:03 is evident. To our knowledge, there has not been any study on HLA association in SINAM in Thai patients. Moreover, there have been very few studies that focus on HLA-DRB1 alleles that associated with SINAM compared to those with self-limited statin associated muscle problems
Objective: To investigate the association(s) between HLA-DRB1 alleles and statin induced necrotizing autoimmune myopathy in Thai cohort.
Method: This is a cross sectional study. High resolution HLA-DRB1 typing was performed in patients with SINAM and the control group (self-limited statin associated muscle problems and patient who receive statin but no side effects). Comparisons was performed between the groups.
Results: 43 patients were enrolled, 2 were later excluded. Among those 41 patients, 9 patients suffered from SINAM, the rest 32 patients were non-immune mediated group (controls). The gender, age and body mass index in the two groups were not differents. HLA-DRB1*11:01 allele was found in 6/9 SINAM patients (66.7%) while it was presented in only 2/32 (6.3%) in the control group (P<0.001, odds ratio 25.66). Other HLA-DRB1 alleles that were found in the SINAM patients were HLA-DRB1*12:02, *13:12, *07:01, *10:01, *-0803, *09:01, *15:01, *15:02, *14:04. In addition, our cohort demonstrated 3 patients with self-limited statin side effect (non-immune mediated) but they were found to have anti-HMGCR antibody
Conclusion: HLA-DRB1*11:01 allele is found to be associated with statin induce necrotizing autoimmune myopathy in a Thai cohort. The utilization of anti-HMGCR antibody test for the diagnosis of SINAM should interpreted alongside specific clinical presentations and other diagnostic findings to differentiate it from other causes of myopathy.
