Safety of intravenous immune globulin in an outpatient setting for patients with neuromuscular disease.

INTRODUCTION: Although intravenous immune globulin (IVIg) is used to treat patients in the outpatient setting, there is limited documentation addressing the safety of this practice. METHODS: Retrospective analysis of 438 patients with neuromuscular diseases receiving IVIg in an outpatient setting. RESULTS: Adverse events (AE) overall occurred in 16.9% of patients. Headache was the most common AE, noted in 11.6% of patients. Serious AEs occurred in 0.91% of patients; aseptic meningitis was the only one noted. Multivariate analyses identified the following risk factors for AEs: first-lifetime course of IVIg, higher dose per course of IVIg, diagnosis of myasthenia gravis, women, and younger age. DISCUSSION: Intravenous immune globulin is generally safe to administer in an outpatient setting. Women, myasthenia gravis patients, and those receiving their first course or a higher total dose of IVIg are at an increased risk of experiencing an AE.

Outcome Evaluation of a Subcutaneous Immunoglobulin Clinical Management Program.

OBJECTIVE: The aim of this study is to compare clinical and cost outcomes of patients undergoing subcutaneous immunoglobulin (SCIG) therapy who were managed by a clinical management program to the matched controls in the United States. METHODS: This was a retrospective cohort study using administrative claims data from the PharMetrics Plus™ (PMTX+) database. The patients from a high-touch SCIG clinical management program were matched to nonprogram patients in PMTX+ database using 1:4 propensity score matching without replacement. All patients were followed for 1 year during the study from September 1, 2011, to June 30, 2014, and both clinical and cost outcomes were compared between the two cohorts using the generalized estimating equation model. FINDINGS: The clinical outcomes were measured by infection- and infusion-related adverse events (AEs). Most of them were not significantly different (P > 0.05) between the intervention group and matched controls. Although the proportion of patients who had a mild less common AE was higher (4.4% vs. 0.0%;P = 0.04), it could be due to increased reporting among the intervention group. The annual adjusted mean total health-care costs of patients in the program (n = 45) were $20,868 lower compared to matched controls (n = 180), representing a 24% lower costs ($66,450 vs. $87,318;P = 0.009). CONCLUSION: This study may demonstrate that clinical management programs for SCIG may be associated with lower health-care costs and comparable infection and severe AE rates. The limitations of this study included a small sample size and a reliance on administrative claim data.

Clinical and economic outcomes of a "high-touch" clinical management program for intravenous immunoglobulin therapy.

OBJECTIVE: To compare clinical and economic outcomes of patients who received intravenous immunoglobulin (IVIG) therapies and were managed by a clinical management program vs the outcomes of matched controls using administrative claim data. METHODS: This retrospective cohort study used the PharMetrics Plus™ claim database between September 1, 2011 and June 30, 2014. Patients in the intervention group were from a "high-touch" IVIG clinical management program administered by a home infusion specialty pharmacy. A greedy propensity score matching algorithm was used to identify a control group from non-program patients. Generalized estimating equation models were employed to evaluate differences between cohorts who were followed for 1 year. RESULTS: Clinical outcomes were measured as infections and infusion-related adverse events. The proportion of patients who had serious bacterial infections was significantly lower (4.13% vs 7.75%, P=0.049) in the intervention group (n=242) compared to the control group (n=968). Other clinical outcomes assessed were not different between cohorts (P>0.050). The economic outcomes were measured as healthcare costs. The annual adjusted mean total health care costs of patients in the program were $26,522 lower compared to matched controls, representing a 20% lower cost ($109,476 vs $135,998, P=0.002). A major contribution to this difference ($17,269) was IVIG-related total outpatient cost (intervention vs control groups: $64,080 vs $81,349, P=0.001). CONCLUSION: The patients in this high-touch IVIG clinical management program appeared to have comparable infections or adverse event rates and significantly lower total health costs compared to their matched controls.

Is IVIg therapy warranted in progressive lower motor neuron syndromes without conduction block?

OBJECTIVE: To evaluate the likelihood of response to IV immunoglobulin (IVIg) by studying consecutive patients presenting with progressive, asymmetric, pure lower motor neuron (LMN) limb weakness, and to determine the clinical phenotype of those who respond. METHODS: Thirty-one consecutive patients with progressive, focal-onset LMN limb weakness, without evidence of clinical upper motor neuron signs; sensory, respiratory, or bulbar involvement; or evidence of motor nerve conduction block on electrodiagnostic studies, were prospectively included in this study. Each patient underwent treatment with IVIg (2 g/kg) for a minimum of 3 months. Electrodiagnostic studies, a neuromuscular symptom score, and expanded Medical Research Council sum score were documented before and after IVIg treatment. The final diagnosis was determined after prolonged clinical follow-up. RESULTS: Only 3 of 31 patients (10%) responded to IVIg. All responders demonstrated distal upper limb-onset weakness, EMG abnormalities confined to the clinically weak muscles, and a normal creatine kinase. This set of features was also identified in 31% of nonresponders presenting with distal upper limb weakness. Sex, age at onset, number of involved limb regions, and the duration of symptoms before treatment were not significantly different between groups. CONCLUSION: The findings of the present study do not support uniform use of IVIg in patients presenting with progressive asymmetric LMN limb weakness. It is suggested that IVIg treatment be limited to patients who demonstrate clinical and laboratory features suggestive of multifocal motor neuropathy. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that IVIg will not improve muscle function in 90% of patients with progressive, asymmetric, pure LMN weakness.

Site directed mutagenesis of Drosophila flightin disrupts phosphorylation and impairs flight muscle structure and mechanics.

Flightin is a myosin rod binding protein that in Drosophila melanogaster is expressed exclusively in the asynchronous indirect flight muscles (IFM). Hyperphosphorylation of flightin coincides with the completion of myofibril assembly and precedes the emergence of flight competency in young adults. To investigate the role of flightin phosphorylation in vivo we generated three flightin null (fln(0)) Drosophila strains that express a mutant flightin transgene with two (Thr158, Ser 162), three (Ser139, Ser141, Ser145) or all five potential phosphorylation sites mutated to alanines. These amino acid substitutions result in lower than normal levels of flightin accumulation and transgenic strains that are unable to beat their wings. On two dimensional gels of IFM proteins, the transgenic strain with five mutant sites (fln(5STA)) is devoid of all phosphovariants, the transgenic strain with two mutant sites (fln(2TSA)) expresses only the two least acidic of the nine phosphovariants, and the transgenic strain with three mutant sites (fln(3SA)) expresses all nine phosphovariants, as the wild-type strain. These results suggest that phosphorylation of Thr158 and/or Ser162 is necessary for subsequent phosphorylation of other sites. All three transgenic strains show normal, albeit long, IFM sarcomeres in newly eclosed adults. In contrast, sarcomeres in fully mature fln(5STA) and fln(2TSA) adults show extensive breakdown while those in fln(3SA) are not as disordered. The fiber hypercontraction phenotype that characterizes fln(0) is fully evident in fln(5STA) and fln(2TSA) but partially rescued in fln(3SA). Mechanics on skinned fibers from newly eclosed flies show alterations in viscous modulus for fln(5STA) and fln(2TSA) that result in a significant reduction in oscillatory power output. Expression of fln(5STA) and fln(2TSA), but not fln(3SA), in a wild-type (fln(+)/fln(+)) background resulted in a dominant negative effect manifested as flight impairments and hypercontracted IFM fibers. Our studies indicate that Thr158 and/or Ser162 are (is) indispensable for flightin function and suggest that phosphorylation of one or both residues fulfills an essential role in IFM structural stability and mechanics.

Flight muscle properties and aerodynamic performance of Drosophila expressing a flightin transgene.

Flightin is a multiply phosphorylated, myosin-binding protein found specifically in indirect flight muscles (IFM) of Drosophila. A null mutation in the flightin gene (fln(0)) compromises thick filament assembly and muscle integrity resulting in muscle degeneration and lost of flight ability. Using P-element-mediated transformation with the full-length flightin gene driven by the Actin88F promoter, we have achieved rescue of all fln(0)-related ultrastructural and functional defects of the IFM. Transgenic P{fln(+)}fln(0) 'rescued' flies have fewer thick filaments per myofbril than wild-type flies (782+/-13 vs 945+/-9) but have otherwise normal IFM. Transgenic P{fln(+)}fln(+) 'tetraploid' flies have a normal number of thick filaments. The flightin protein levels in both transgenic strains are similar to wild type. By contrast, flightin levels are reduced in a myosin heavy chain tetraploid strain that produces excess myosin and excess thick filaments. These results suggest that regulation of flightin protein level is independent of gene copy number and that the number of thick filaments assembled per myofibril is influenced independently by myosin and flightin expression. We measured mechanical properties of IFM skinned fibers by sinusoidal analysis and found no significant differences in active viscoelastic properties of flightin-rescued and tetraploid transgenic flies vs wild type. The ability of the fln(+) transgene to overcome deficits in dynamic stiffness and power output in fln(0) suggest that the flightin protein contributes directly to fiber stiffness and stretch activation. However, flight parameters at maximum locomotor capacity, measured in a virtual reality flight simulator, are slightly compromised for both transgenic strains. P{fln(+)}fln(0) and P{fln(+)}fln(+) flies generated enough flight force to sustain hovering flight but showed reduced capability to produce forces in excess of hovering flight force. Both strains showed reductions in stroke frequency but only P{fln(+)}fln(+) showed reductions in stroke amplitude. Muscle and aerodynamic efficiency are similar among the two transgenic strains and wild type. These results illustrate the importance of flightin in flight muscle development and function.

Flightin is a myosin rod binding protein.

The assembly of striated muscle myosin into thick filaments of precise and regular length requires the assistance of accessory proteins. Drosophila indirect flight muscle (IFM) contain flightin, a 20-kDa protein that has been shown to be essential for flight, for maintenance of sarcomeric integrity in active muscle, and informative in length determination of thick filaments during IFM development. Additionally, a point mutation in the myosin rod (Mhc(13)) negates flightin accumulation in the IFM in vivo. The manner in which flightin interacts with thick filaments is not known. Here, two different solid-state binding assays demonstrate that flightin binds to myosin and to a recombinant fragment of the myosin rod that include the COOH-terminal 600 amino acids (zone 19 to tail piece). The interaction of flightin and myosin is abolished by the single amino acid substitution in Mhc(13) at position 1e of zone 27 of the rod (residue 1554). The molar ratio of flightin to myosin is approx 1 : 1 to 1 : 2. Thus, the instability of thick filaments seen in vivo in the absence of flightin suggests that the flightin myosin interaction is critical for maintaining sarcomere integrity in active muscle.