title: The yield of diagnostic work-up of patients presenting with myalgia, exercise intolerance, or fatigue: A prospective observational study.
abstract: Myalgia, fatigue, and exercise intolerance are cause for referral to a neurologist. However, the diagnostic value of history, neurological examination, and ancillary investigations in patients with these symptoms is unknown. This study provides a sound footing for deciding which ancillary investigations should be conducted. A prospective observational study of the diagnostic approach in 187 patients with myalgia, exercise intolerance, or fatigue as their predominant symptom was performed. The primary outcomes were independent contribution of referral letter, history, examination, and ancillary investigations to a myopathy diagnosis. The secondary outcome was diagnostic value of combined ancillary investigations. 27% of patients had a myopathy. Positive family history (OR 3.2), progressive symptoms (OR 2.2), atrophy (OR 9.7), weakness (OR 10.9), and hyporeflexia (OR 4.4) were associated with a myopathy. Positive predictive values for myopathy were calculated for CK (0.32), EMG (0.66), ultrasound (0.47), and muscle biopsy (0.78). All contributed significantly in predicting myopathy. Multivariate analysis yielded a diagnostic algorithm facilitating a more efficient work-up in future patients. CK levels, EMG, ultrasound, and muscle biopsy independently contribute to predicting a myopathy. The diagnostic algorithm shows which combination of ancillary investigations should be employed in different subgroups and when to omit invasive techniques. This algorithm may drastically improve diagnostic efficiency.
authors.affiliation: Neuromuscular Centre Nijmegen, Department of Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: M G E
authors.initials: MG
authors.lastname: Te Riele
authors.affiliation: Neuromuscular Centre Nijmegen, Department of Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands. Electronic address: tim.schreuder@radboudumc.nl.
authors.forename: T H A
authors.initials: TH
authors.lastname: Schreuder
authors.affiliation: Neuromuscular Centre Nijmegen, Department of Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands; Department of Clinical Neurophysiology, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: N
authors.initials: N
authors.lastname: van Alfen
authors.affiliation: Neuromuscular Centre Nijmegen, Department of Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Bergman
authors.affiliation: Department of Clinical Neurophysiology, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Pillen
authors.affiliation: Department of Neurology, Maasstad Hospital, Rotterdam, The Netherlands.
authors.forename: B W
authors.initials: BW
authors.lastname: Smits
authors.affiliation: Department of Epidemiology, Biostatistics and Health Technology Assessment, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: van der Wilt
authors.affiliation: Department of Epidemiology, Biostatistics and Health Technology Assessment, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Groenewoud
authors.affiliation: Neuromuscular Centre Nijmegen, Department of Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: N C
authors.initials: NC
authors.lastname: Voermans
authors.affiliation: Neuromuscular Centre Nijmegen, Department of Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: B G M
authors.initials: BG
authors.lastname: van Engelen
mesh_terms: D000328:Adult; D003402:Creatine Kinase / Q000097:blood; D005221:Fatigue / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000097:blood / Q000150:complications / Q000175:diagnosis*; D063806:Myalgia / Q000175:diagnosis* / Q000209:etiology
chemical_list: D003402:Creatine Kinase
keywords: All neuromuscular diseases; EMG; Mitochondrial disorders; Muscle biopsy; Muscle disease; Myalgia; Myopathy; Ultrasound