Application of the Statin-Associated Muscle Symptoms-Clinical Index to a Cohort of Patients with Type 2 Diabetes Mellitus Undergoing Phlebotomy at an Endocrinology Clinic

Background: Statin-associated muscle symptoms (SAMS), the commonest statin-induced adverse effects, could hinder patient adherence and possibly lead to discontinuation of therapy, which then increases patients’ risks for developing cardiovascular events. Although statins are the most frequently prescribed lipid-lowering medication, the occurrence and severity of SAMS among the Malaysian population are less known. Objectives: To examine the likelihood and types of muscle symptoms attributable to statins, and the risk factors for developing the symptoms among statins users. Materials and Methods: This was a cross-sectional study conducted with convenience sampling of patients with type 2 diabetes mellitus undergoing phlebotomy at an endocrinology clinic of a secondary hospital in a suburban city. Demographic and clinical data for the evidence of SAMS were retrieved from the hospital information system. A total of 214 patients were screened, and 50 subjects were recruited for interviews based on the study’s inclusion and exclusion criteria. Muscle symptoms that were evident through clinician notes, and self-reported signs and symptoms by patients during the interview were assessed to determine whether they were SAMS or not. This was done using a pre-structured published questionnaire via patient interview, and the likelihood was then determined using the SAMS-clinical index (SAMS-CI) tool. Results: In this cohort, the probability of having had a statin-associated muscle adverse event was 0.48, i.e., 48% “probable” and “possible” likelihood of SAMS having occurred for a patient who consumed a statin. The mean SAMS-CI score was 6.32 ± 0.470 (±7.4%) [CI: 5.85–6.79], which fell under an “unlikely” category. The most frequent type of muscle symptom was myalgia, which was experienced as muscle aches, stiffness, cramps, symptoms worsening after exercise, muscle tenderness, and trouble moving knees or arm joints. These symptoms were proximal and symmetrical in nature and commonly involved large muscle groups such as the thighs, buttocks, calves, and back muscles. An elevation in creatinine kinase was not commonly observed. Conclusion: A minority (6%) of the patients that we sampled experienced SAMS, which were probably attributable to statins. Nevertheless, caution must be exercised for female patients with a familial history of heart disease being prescribed with the lipophilic statins, atorvastatin, and simvastatin, and those who report aches in the large muscle groups.