Table 1. Clinical Characteristics of Patients with Statin-Triggered Autoimmune Myopathy Who Received Intravenous Immune Globulin Monotherapy*.
| Characteristic | Patient 1 | Patient 2 | Patient 3† |
|---|---|---|---|
| Age (yr) | |||
| At start of statin | 57 | 53 | 63 |
| At onset of muscle-related symptoms | 57 | 53 | 67 |
| At discontinuation of statin | 57 | 65 | 68 |
| At first IVIG treatment | 63 | 65 | 69 |
| Evaluation immediately before IVIG | |||
| Creatine kinase (IU/liter) | 8916 | 2323 | 3517 |
| Strength | |||
| Arm abductors | |||
| Contraction against resistance | |||
| Right | 4 | 4+ | 4 |
| Left | 4 | 4+ | 4 |
| Weight resisted (kg) | |||
| Right | 2.7 | 5.0 | 2.7 |
| Left | 2.7 | 5.0 | 3.2 |
| Hip flexors | |||
| Contraction against resistance | |||
| Right | 2 | 4 | 4 |
| Left | 2 | 4 | 4 |
| Weight resisted (kg) | |||
| Right | NA | 13.6 | 6.4 |
| Left | NA | 12.2 | 6.4 |
| Anti–HMG-CoA reductase antibody titer (NAU) | 0.845 | 0.566 | 1.650 |
| First evaluation after IVIG | |||
| Time since first IVIG (mo) | 3.5 | 2 | 1.5 |
| Creatine kinase (IU/liter) | 2368 | 270 | 738 |
| Strength | |||
| Arm abductors | |||
| Contraction against resistance | |||
| Right | 5− | 5 | 5 |
| Left | 5− | 5 | 5 |
| Weight resisted (kg) | |||
| Right | 4.5 | 8.6 | 5.9 |
| Left | 4.1 | 8.6 | 5.4 |
| Hip flexors | |||
| Contraction against resistance | |||
| Right | 4− | 5 | 4+ |
| Left | 4− | 5 | 4+ |
| Weight resisted (kg) | |||
| Right | 5.4 | NA | 10.4 |
| Left | 6.8 | NA | 12.7 |
| Anti–HMG-CoA reductase antibody titer (NAU) | 0.654 | 0.438 | 1.242 |
| Most recent evaluation | |||
| Time since first IVIG (mo) | 9 | 19 | 15 |
| Creatine kinase (IU/liter) | 1755 | 64 | 877 |
| Strength | |||
| Arm abductors | |||
| Contraction against resistance | |||
| Right | 5 | 5 | 5 |
| Left | 5 | 5 | 5 |
| Weight resisted (kg) | |||
| Right | 6.8 | NA | 5.9 |
| Left | 6.4 | NA | 8.2 |
| Hip flexors | |||
| Contraction against resistance | |||
| Right | 4+ | 5 | 5 |
| Left | 4+ | 5 | 5 |
| Weight resisted (kg) | |||
| Right | 13.6 | NA | NA |
| Left | 12.7 | NA | NA |
| Anti–HMG-CoA reductase antibody titer (NAU) | 0.764 | 0.471 | 1.179 |
Extent of muscle contraction against resistance was measured with the use of the Medical Research Council scale, in which 0 indicates no movement and 5 indicates normal contraction. Quantitative muscle strength testing was performed with a MicroFet2 handheld dynamometer (Hoggan Scientific). Arm abductors were tested with arms laterally abducted at 90 degrees, and hip flexors were tested with patient supine and leg raised to 30 degrees. Anti–HMG-CoA-receptor titers were determined as previously reported with values greater than 0.367 normalized absorbance units (NAU) considered positive. 5 HMG-CoA denotes 3-hydroxy-3-methylglutaryl coenzyme A, IVIG intravenous immune globulin, and NA not available.
This patient was treated unsuccessfully with oral glucocorticoids and azathioprine for several months, but these medications were discontinued more than a year before IVIG initiation.