The insidious impact of under-diagnosed proximal weakness induced by statins

Introduction: This Perspective reassesses the consensus opinion that statin-associated muscle symptoms (SAMS) occur in <1% of users and associated myopathic proximal muscle weakness is even more rare.Areas covered: Of the over 180,000 participants in clinical trials and large registries of statin users, only a few studies have included a standard manual muscle test (MMT), dynamometry or a focused questionnaire to assess for proximal weakness and related disability in daily and recreational activities. Formal strength testing suggests, however, that weakness can be demonstrated in at least 10% of users.Expert opinion: Reporting inaccuracies about SAMS, confirmation bias among experts and physicians, absence of a standard questionnaire regarding the potential consequences of weakness on physical capacity, and the failure to routinely perform an objective assessment of strength may have led to under-diagnosis of statin-induced myopathy. A brief MMT before cholesterol-lowering agents are started and at follow-up visits, a 12-week withdrawal of the statin in the presence of new paresis without an alternative cause, and the exam finding that strength recovers off the statin are necessary to assess the incidence of drug-induced proximal weakness and inform alternative therapeutic strategies.