Optimal volume of processed plasma and total number of selective plasmapheresis sessions in the treatment of patients with severe generalized myasthenia gravis

Efficacy and safety of double-filtration plasmapheresis treatment of myasthenia gravis: A systematic review and meta-analysis

OBJECTIVES

To evaluate the efficacy of double-filtration plasmapheresis (DFPP) treatment of myasthenia gravis (MG) through a systematic review and meta-analysis.

METHODS

PubMed, Cochrane Library, Embase, China National Knowledge Infrastructure (CNKI), Chinese Scientific Journals Database (VIP), and Wanfang databases were searched for randomized controlled trials (RCTs) and clinical controlled trials (CCTs) on DFPP for MG from database establishment to June 2019. Two researchers independently screened the articles, extracted the data, and cross checked the results. RevMan 5.3 was used for statistical analyses.

RESULTS

Seven RCTs and 2 CCTs were found comprising 329 patients. The results showed that clinical MG remission rate after DFPP treatment was significantly higher (OR = 4.33; 95% confidence interval [CI], 1.97-9.53; P < .001) and the serum levels of antititin antibody was significantly decreased (standardized mean difference [SMD] = 9.30; 95% CI, 7.51-11.08; P < .001). In addition, the quantitative MG (QMG) score, hospital stay and time to remission of MG symptoms, and acetylcholine receptor antibody (AchRAb) decreased in the DFPP treatment group; however, these outcomes had high heterogeneity among the studies. Only one study has reported on the adverse effects, including hypotension and hematoma.

CONCLUSION

This meta-analysis suggests that DFPP can be recommended for the short-term mitigation of MG. Because our review was limited by the quantity and quality of the included studies, the above conclusions should be verified by additional high-quality studies.

Therapeutic apheresis within immune-mediated neurological disorders: dosing and its effectiveness

Plasma exchange (PE) and immunoadsorption (IA) are standard therapeutic options of immune-mediated neurological disorders. This study evaluates the relation of the relative quantity of applied dose of PE and/ or IA and its achieved therapeutic effectiveness within the treated underlying neurological disorders. In a retrospective study, we evaluated data from PE and IA carried out 09/2009-06/2014 in neurological patients at the University-Hospital of Saarland, Germany. Apheresis dose was defined as the ratio of the extracorporeal treated plasma volume to the patient's plasma volume. Effectiveness was assessed through disease-specific tests and scores by the attending neurologist(s); results were classified into response or no response. 1101 apheresis (PE:238, IA:863), in 153 hospital-stays were carried out, averaged, 7.0 treatments per patients, 82% responded, 18% not. Mean applied apheresis dose per treatment was 0.91 with mean doses of 1.16 for PE and 0.81 for IA. The totally applied mean dose per stay was 5.6 (PE:5.01, IA:5.81). No correlation was seen between apheresis dosing and treatment effectiveness (PE:R2 = 0.074, IA:R2 = 0.0023). PE and IA in therapy-refractory immune-mediated neurological disorders majorly achieved a measurable severity improvement - without correlation to the applied dose. Moreover, our data rather suggest, that effectiveness may be given with volumes below currently recommended volumes.

MuSK antibody clearance during serial sessions of plasmapheresis for myasthenia gravis

To evaluate the relationship of antibody clearance and clinical improvement for myasthenia gravis (MG) patients with MuSK antibody (MuSKAb) receiving one course of double-filtration plasmapheresis (DFP) treatment, we prospectively recorded their MG scores and measured MuSKAb concentrations before and after each DFP treatment session in two MuSKAb-positive patients. The clinical improvement trends roughly paralleled the reductions of MG score, except for the late rebound of MuSKAb in the 6th DFP treatment session, without concomitant clinical worsening in one patient. Longitudinal analysis on the serological changes during the serial sessions revealed that the levels of MuSKAb fell by 44%, 59%, 79%, 82%, 92%, and 71% in patient 1 and 52%, 70%, 78%, 87%, and 90% in patient 2. The titers of MuSKAb decreased constantly during the first 5 DFP treatment sessions. MuSKAb clearance per session for the 11 sessions ranged from 19% to 56%, with a mean of 45%. In conclusion, DFP was effective for MuSKAb removal and amelioration of clinical weakness for our two patients with MuSKAb. A 5-session protocol cleared 90% of serum MuSKAb.

Therapeutic plasma exchange in the treatment of neuroimmunologic disorders: Review of 50 cases

Therapeutic plasma exchange (TPE) has been used for the treatment of neurologic diseases in which autoimmunity plays a major role. We reviewed the medical records of our patients who had consecutively been treated by TPE between January 1998 and June 2000. Neurological indications included myasthenia gravis (30 patients), multiple sclerosis attack (6 patients with remitting-relapsing course and 3 patients with secondary progressive course), Guillain-Barrè syndrome (6 patients), paraproteinemic neuropathy (2 patients), and chronic inflammatory demyelinating neuropathy (CIDP), transverse myelitis due to systemic lupus erythematosus, acute disseminated encephalomyelitis in one patient each. Continuous flow cell separators were used for TPE. TPE was generally given every other day for all of the patients and one plasma volume was exchanged for each cycle. Although the patients with secondary progressive multiple sclerosis (3 patients) and paraproteinemic neuropathy (2 patients) did not show any improvement after TPE, other patients' targeted neurological deficits were improved by TPE. During the TPE procedures, no patient had any morbidity or mortality, and the complications were mild and manageable such as hypotension, hypocalcemia and mild anemia; three patients had septicemia due to the venous catheter used for TPE. TPE is an effective treatment in neurologic diseases in which autoimmunity plays an important role in pathogenesis, and it is safe when performed in experienced centers.

Clearance Studies During Subsequent Sessions of Double Filtration Plasmapheresis

To evaluate the optimal session of double filtration plasmapheresis (DFP) in terms of the maximal clearance rates for various serum substances, the laboratory parameters of 152 consecutive patients treated with different sessions of DFP following a standard protocol on an alternate-day basis was studied. Immunoglobulin M (IgM) and lipoprotein cholesterol had the most effective clearance by a minimum of two sessions of DFP treatment, and the clearance rates remained relatively constant despite the increase in the number of treatment sessions, while the clearance rates for other serum proteins increased steadily with further treatments. Using the clearance rate of the 2-session group as reference, the highest slopes for clearance of albumin, globulin, and triglyceride were found in the 4-session group, while the slopes for IgA and IgG were highest in the 5-session group. In conclusion, for the clearance of IgM and lipoprotein cholesterol, two sessions of DFP treatment are adequate. However, the best clearance of IgG and other globulins cannot be achieved until the fourth session of DFP treatment. Therefore, a minimum of 4 sessions of DFP treatment at 2-day intervals is needed for most immunological diseases.

Prethymectomy plasmapheresis in myasthenia gravis

Plasma exchange before thymectomy may decrease the time on mechanical ventilation (MV) and shorten the stay in the intensive care unit (ICU) for patients with myasthenia gravis (MG). This study evaluated the effects of prethymectomy plasmapheresis. A total of 29 myasthenic patients, 18 women and 11 men aged 20-73 years, were treated with double filtration plasmapheresis (DFP) for two to five consecutive sessions over a period between 2 and 21 days (mean 8.1 days) before transsternal thymectomy. Acetylcholine receptor antibody (AchRAb) titers, vital capacity (VC), maximal inspiratory pressure (Pimax), and MG score were measured before and after the course of DFP. Three outcome measures including duration of postoperative hospital stay, duration of ICU stay, and duration of MV were analyzed for correlation with clinical variables. The duration of MV ranged from 6 to 93 h, with a median of 21 h. The median ICU stay was one day and the median postoperative hospital stay was 10 days. A higher removal rate of AchRAb was associated with a shorter duration of ICU and postoperative hospital stay (P = 0.001 and 0.019, respectively). Postoperative hospital stay was strongly correlated with post-DFP Pimax (P = 0.010), and marginally correlated with pre-DFP VC (P = 0.047) and to a lesser extent with pre-DFP Pimax (P = 0.063). Univariate analysis using the log rank test revealed that removal rate of AchRAb <30% (P = 0.043) and pre-DFP Pimax <-60 cmH2O (P = 0.024) were significantly associated with prolonged ICU stay. Risk factors for prolonged postoperative stay included post-DFP Pimax <-60 cmH2O (P = 0.017), pre-DFP Pimax <-60 cmH2O (P = 0.031), and post-DFP VC < 1.0 L (P = 0.046). Our results confirmed the efficacy and safety of DFP in prethymectomy preparation for myasthenic patients.

Clearance of fibrinogen and von Willebrand factor in serial double-filtration plasmapheresis

Double filtration plasmapheresis (DFP) is a widely used and effective way to clear autoantibodies from plasma. It can, however, transiently alter the hemostatic system and cause a bleeding tendency in some patients. There is limited data on the consecutive effect of serial DFP on the hemostatic system, especially on fibrinogen and von Willebrand factor (vWF) levels. This study measured fibrinogen and vWF serially before and after each session of DFP in 8 patients who received one course of DFP treatment for 3 to 5 consecutive sessions on an alternate-day basis. In each session of DFP, the clearance rate of fibrinogen and vWF exceeded 63 and 45%, respectively. The final levels of fibrinogen and vWF after a full course of DFP were reduced to 14.3 and 51.2% of baseline level, respectively. No bleeding tendency was observed in any of the 34 DFP sessions. In conclusion, although an obvious decrease in fibrinogen level and the modest decrease in vWF were observed after an intensive course of DFP treatment, the low incidence of clinically important bleeding confirms the hemostasis-related safety of DFP.

Predicting the course of myasthenic weakness following double filtration plasmapheresis

OBJECTIVE

To evaluate the clinical course of patients with myasthenia gravis (MG) up to 3 months after double filtration plasmapheresis (DFP).

MATERIAL AND METHODS

We recorded the MG score and measured the level of acetylcholine receptor antibody (AchRAb) at baseline and day 1 (D1), week 1 (W1), 1 month (M1), 2 (M2) and 3 months (M3) after DFP in 16 MG patients. Based on the difference in score during follow-up, we divided our patients into clinical improvement (CI) and clinical worsening (CW) groups.

RESULTS

The MG score decreased in all courses from a mean of 8.1 at baseline to 5.6 at D1, and to 4.7, 4.0, 3.8, and 3.7 at W1, M1, M2, and M3, respectively. In the CW group, AchRAb levels were significantly higher at M1 (P = 0.022). The AchRAb level at W1 correlated significantly with the MG score at M3 (P = 0.027) and the changes of MG score from W1 to M1 (P = 0.029). The ratio of AchRAb levels of M1 to W1 correlated well with MG score at W1 (P = 0.032), at M3 (P = 0.001), and the changes of MG score from W1 to M1 (P = 0.004).

CONCLUSION

Excessive rebounds of AchRAb level at W1 may suggest clinical worsening and further increases in AchRAb level at M1 predict poorer outcome after DFP.

Hemodynamic study of serial double-filtration plasmapheresis

Although hypotension is a potential complication for all procedures involving extracorporeal circulation, including plasmapheresis, the effects of serial double-filtration plasmapheresis (DFP) on hemodynamic status have rarely been reported. Blood pressure (BP) and pulse rate (PR) were prospectively monitored at 30-minute intervals (baseline, M30, M60, M90, and Ml20) during procedures for 20 myasthenia gravis patients who underwent one course of five consecutive DFP treatments on alternate days, with hemodynamic parameters recorded and analyzed for all sessions. To evaluate the hemodynamic influence of protein loss resulting from serial DFP treatment, additional analysis of serum protein levels including albumin and globulin was conducted before and after the entire course of treatment. Longitudinal analysis on the systolic BP (SBP) changes over five sessions revealed that the SBP at baseline and at M30 dropped significantly during the third and fourth sessions, in comparison to the first (P < 0.05). By contrast, SBP at M120 rose significantly (P < 0.05) after the second session of treatment. A similar trend was revealed for the diastolic BP (DBP) with a significant fall recorded at baseline and at M30 for the fourth session. The PR did not differ significantly during consecutive DFP treatments. Globulin removal rates were correlated significantly with falls in SBP (r(2) = 0.250, P = 0.048) and DBP (r(2) = 0.405, P = 0.008). However, analogous albumin removal rate was not correlated with these hemodynamic parameters. In conclusion, our results confirm that hypoproteinemia is an important factor for contributing to unstable hemodynamics during serial DFP.

Double filtration plasmapheresis in the treatment of myasthenic crisis--analysis of prognostic factors and efficacy

OBJECTIVES

To examine the prognostic factors and outcome of myasthenia gravis (MG) patients in crisis with double filtration plasmapheresis (DFP) treatment.

MATERIAL AND METHODS

A total of 15 patients experienced 20 episodes of crisis during the study period. Plasmapheresis was carried out using a double filtration

METHOD

Demographic information, clinical features of crisis, and associated complications were analyzed.

RESULTS

The median duration of crisis was 9 days. Chest infection was the most common precipitant of crisis. Twelve out of the 20 episodes (60%) responded well to DFP and mechanical ventilation was discontinued after the third session of DFP in 8 of them. Three significant predictors for prolonged crisis were shorter intervals between the onset of MG and the first crisis (P=0.04), higher serum bicarbonate levels at baseline (P=0.03) and the thymic pathology of thymoma (P=0.03).

CONCLUSION

DFP can ameliorate the profound weakness in crisis and seems to be a rational therapy for patients with myasthenic crisis.

Immunoadsorption, current status and future developments

The association of abnormalities in the cellular and humoral immune system with various autoimmune diseases provides the rationale for apheresis technologies. While plasmapheresis or plasma exchange is limited by its non-selective removal of all plasma components, modern apheresis techniques aim to provide more specific elimination according to clinical needs and avoid plasma product replacement. However, the commercialisation has not met the expectations in the early 80's and the number of patients treated by extracorporeal immunoadsorption remains small due to a lack of well-defined controlled trials and limited reimbursement. This review highlights the immunological and technical basis for extracorporeal immunoadsorption, as well as its current status in the treatment of immunologically-mediated diseases.

The six year experience of plasmapheresis in patients with myasthenia gravis

Plasmapheresis (PP) effectively removes autoantibodies in various autoimmune diseases. The use of PP in the treatment of myasthenia gravis (MG) has been widely accepted since the 1970s. The treatment protocol, however, has not been standardized. For the last 6 years, we collected a total of 94 MG patients, 38 males and 56 females aged 14-80 years, who received 175 courses of PP treatment for a total of 823 sessions. The methods we used were double filtration plasmapheresis (DF), immunoadsorption plasmapheresis (IA), and plasma exchange (PE). There were 167 courses of DF, 6 courses of IA, and 2 courses of PE. Each course of treatment consists of 4 to 5 sessions of apheresis. The processed volume of plasma is 1 calculated plasma volume. All patients tolerated PP well although 2.3% of them experienced hypotension. Our experiences are summarized as follows. Both DF and IA effectively ameliorate symptoms and signs of MG. IA removes acetylcholine receptor antibody more effectively than DF does, but clinical effects between these 2 methods are similar. A daily schedule seems more effective than an alternate daily schedule. The optimal number of PP sessions for each course is 4. The factors correlating with better clinical response are high MG score, nonthymoma patients, younger age at onset, and higher removal rate for immunoglobulin G.