Thrombotic thrombocytopenic purpura: outcome in 24 patients with renal impairment treated with plasma exchange G. ROCK,K. SHUMAK, J. KELTON,V.S. BLANCHE-ITE, N. BUSKARD, R. NAIR,R. SPASOFF, AND THE CANADIAN APHERESIS STUDY GROUP The Canadian Apheresis Study Group recently completed a randomized clinical trial involving 102 patients with thrombotic thrombocytopenic purpura WP), in which treatment with plasma infusion and treatment with plasma exchange were compared. Thirty-three other patients were ineligible or refused to be randomly assi ned in the trial. Of the 33 patients, 24 were assessed as ineligible because they woul be unable to tolerate the fluid input that would occur if they were randomly assigned to receive plasma infusion. All 24 patients had oliguria and elevated creatinine and/or blood urea nitrogen level. These 24 patients were treated with acetylsalicylic acid, dipyridamole, and plasma exchange according to the standardized protocol defined in the trial. Blood for tests of factors possibly involved in the pathogenesis of l T P was drawn before exchange and at intervals during and after exchange. The mean platelet count before exchange was 35.5 x 1Og per L. In 12 of the 24 patients, the platelet count reached 150 x log per L or greater by 7 days after the initiation of plasma exchange. Three patients responded partially, in that their platelet count increased to at least twice that at presentation, but remained below 150 x l o e per L. One patient died during the first week. Of the eight other patients who experienced treatment failure at the 7-day assessment point, six subsequently responded, four while continuing to receive plasma exchange and two after plasma exchange had been discontinued. Of the 15 patients who either responded fully or responded partially by the end of the first cycle, all survived. A total of 4 of the 24 patients died, including the 1 patient who died during the first cycle of treatment. Thus, these patients, who had what some would consider to be the adult hemolytic uremic syndrome, did not differ in their response to plasma exchange from the patients in the randomized trial with less prominent renal dysfunction. The von Willebrand factor antigen level was elevated at presentation in patients who did and patients who did not respond, averaging 438 percent. The levels of several other circulating factors thought possibly to be related to the pathogenesis of l T P did not show consistent abnormalities and did not differ in patients who did or did not respond to plasma exchange. TRANSFUSION 1992;32:710-714.
%
Abbrevlations: C l q = l W C l q Immune complex test; FVlll = factor VIII; HMW = hlgh molecular weight; HUS = hemolytlc uremic syndrome; PAF = piatelet-agglutlnatlng factor; PE = plasma exchange; :TTP = thrombotic thrombocytopenlc purpura; vWF:Ag = von Willebrand factor antlgen.
plasma infusion and PE therapy in 7TP, the Canadian Apheresis Study Group undertook a multi-center, randomized, prospective trial of these treatments from 1983 through 1989. All patients with 'ITP at 16 participating centers across Canada were considered for the study. The study showed that PE i s more effective than plasma infusion in the treatment of TTP.' The eligibility criteria for patients to be included i n this trial were a platelet count of less than 100 x lo9 per L, microangiopathic hemolytic anemia, and no other cause for thrombocytopenia or microangiopathic hemolytic anemia. Because these patients might be randomly assigned to receive plasma infusion, an additional criterion for eligibility was that a patient be considered able to tolerate the fluid load of plasma infusion. Patients with congestive heart failure or severe oliguria were
CURRENT TREATMENT OF PATIENTS with thrombotic usually includes plasma thrombocytopenic purpura (") therapy, either as infusion of fresh-frozen plasma or as plasma exchange (PE) using fresh-frozen plasma as the replacement fluid. In addition, anti-platelet drugs are commonly employed. To compare the effectiveness of From the Departments of Medicine, Pathology, Epidemiology, and Biochemistry, University of Ottawa, Ottawa, Ontario; the Departments of Medicine and Pediatrics, University of Toronto, Toronto, Ontario; the Department of Pathology, McMaster University, Hamilton, Ontario; and the Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada. Supported in part by the Canadian National Health Research Dcvelopment Program, National Health & Welfare, Canada Grant No. 6613-1158 (JK). Rcceived for publication September 5, 1991; revision received March 17, 1992, and accepted April 2, 1992.
710
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Table 1.
Features at presentation and response to treatment in 24 patients with 77P* and oliguria At presentation
Platelet countt Hb* BUNS Creatinines ( x loe/L) (gL)(pmolR) (pmol/L)
Fever7 (OC)
FNA"
Patient ID Code
1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18 19 20 21 22 23 24
20 10 35 120 33 70 13 27 14 56 20 51 21 19 34 10 29 13 88 42 61 11 16 17
104 92 84 76 106 94 102 81 90 92 69 NT
73 118 119 81 90 92 74 94 101 103 108 71
27.8 22.8 42.0 7.9 34.8 26.7 42.1 28.2 29.4 37.4 38.2 16.8 9.7 8.8 29.3 26.5 13.3 11.1 51.6 21.6 15.1 17.2 24.0 18.6
203 156 398 168 690 187 884 371 591 138 946 245 124 149 424 333 206 195 815 199 278 128 378 145
-
+ -38.7 -
-
-
+ (38.5) + (38.5) + (38.7) -
-
-
+ + + + +
+
+ -
+
-
+ (38.5) + + + (38.5) +
Thrombotic thrombocytopenlc purpura.
*Q
+ + + + +
t Normal range, 150400 x 100 per L. Hemoglobin; normal range, 120-175 g per L Blood urea nitrosen; normal range, 1.8-8.2m o l per L. II Normal range, 46-110 pmol per 11 Normal, 37.0"C; - = condition not present; + = condition present. ** Focal neurologic abnormalities; normal, - .
L.
therefore considered ineligible. A total of 102 patients were recruited into the trial, but, in addition, data were collected on 33 other patients who were not randomly assigned. Of these 33, 24 did not meet the eligibility criteria because of renal dysfunction. This group of patients with renal dysfunction represents a category separate from those in our randomized trial.' The renal involvement could lead some to diagnose these patients as having hemolytic uremic syndrome (HUS); certainly, if considered to have TI", these patients could be said to have a more aggressive form of the disease than those with normal renal function. The present report describes the clinical and laboratory presentation and the outcome in these 24 patients with 'ITP and shows that, even in a severe form of disease, PE can be an effective treatment. Materials and Methods Patients considered for eligibility for entry into the randomized trial were first identified by the treating physician as having TIT. The randomization center was then contacted and the center verified that the patient had thrombocytopenia (a platelet
After treatment History RBC of T T P t t fragments**
NT NT NT -
-
-
-
Platelet Reticulocyte count count§§ Outcome11 II ( x lO'/L)
+ + + + + + + + + + + + + + + + + + + + + + +
tt Normal, -. Red cell fragments; normal,
**§I
Elev Elev Elev Elev Elev Elev Norm Elev Elev Elev NT Elev Elev Norm Norm Elev NT Elev Elev Elev Elev Elev Elev Norm
R PR F
R R R R R R F PR F F R D R F F R R
R PR F F
200 94 45 208 186 195 374 195 254 71 139 20 10 265 D
269 30 20 334 21 1 202 142 20 15
+.
Elev = elevated; Norm = normal; NT = not tested. 11 11 Assessed on Day 7 of treatment on the basis of the platelet count: R = response; PR = partial response; F = treatment failure: D = death.
count < 100 x 109/L) with microangiopathic hemolytic anemia. Any other identifiable cause for these findings led to ineligibility, as did any history of congestive heart failure or anuria that, in the opinion of the attending physician, would render the patient unable to tolerate plasma infusion. Patients considered ineligible for the randomized trial because of oliguria are the subject of the present report. Blood counts were measured by the method of choice at each participating hospital. All other tests were done centrally on appropriate samples; the specimens for platelet-specific antibody were sent by courier for testing within 24 hours of collection. Patients were treated with daily PE (1.5 X plasma volume) for the first 3 days and then single-volume PE to a total of seven exchanges within 9 days of starting treatment. Patients were also given dipyridamole (400 mg/day) and acetylsalicylic acid (325 mglday) orally. Fresh-frozen plasma was used for replacement in all cases. We assessed patients after seven procedures (between Days 7 and 9) and classified them as having responded fully, having responded partially, or having failed to respond. Outcome was determined according to the absolute platelet count, the platelet increment, and the neurologic status of the patient. We defined a complete response as an improvement in the platelet count to greater than 150 x lo9 per L on at least two consecutive days and no new neurologic events.
712
TRANSFUSION Vol. 32. No. 8-1992
ROCK ET AL. Table 2.
Patlent
ID code
vWF:Agt
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
NT NT NT NT NT NT NT NT
Putative pathogenic factors in 24 patients with 77P* and oliguria
Factor Vlll multimers*
Raji cell
(titer)§
NT NT NT NT NT NT NT NT NT NT NT NT Decr NT NT Norm Norm Norm Norm Norm NT NT NT NT
525 248 352 300 264 183
NT 300 1390 420 360 520
NT NT NT NT
64 -
-
32 32 128 128 -
-
32 64 64 32
NT NT NT NT
* Thrombotic thrombocytopenic purpura.
t Von Willebrand factor:antigen; normal, 40-150; NT
* Norm normal: Decr Normal, negative =
=
decreased.
=
not tested.
Immune complexes PEG (pt.lNpool)ll
Platelet antibody
c1qll
DIRMAii
(fglplt)
PAFtt
1.98 4.64 0.82 0.59 1.10 1.07 2.77 3.28 2.66 2.39 0.89 2.90 0.89 0.78 2.11 9.66 1.09 1.74 1.46 8.29
0.9 1.2 0.6 1.4 1.1 0 1.1 1.1 4.8 0 0 13.2 10.4 26.0
6.7 27.6
-
NT
NT
NT
NT
7.2 2.4 3.9 0 1.1
14.6 7.1 10.4
NT NT
NT NT NT NT
0.50
NT
(“w
-
6.2 13.0 2.3 16.0 4.7 7.9 3.9 8.0 7.0
NT
NT
-
13.1
NT 6.0 72.2 26.2
NT 23.2
-
+ + + + + +
NT NT
+ + +
NT NT NT NT NT
7 lZ5l= Clq assay: normal, 0. i i Direct immunoradiometric assay; normal, 5.5 fg per platelet. tt Platelet-aggutinating factor: normal, negative (-).
(-).
§
11 Polyethylene glycol test (patient platelets compared to normal pool): normal, 1 .
A partial response was defined as a platelet count between 50 and 150 x lo9 per L with a platelet increment of greater than 100 percent and no new neurologic events. We considered patients to have failed to respond 1) if the platelet count was less than 50 x lo9 per L, 2) if the platelet count was less than 100 x lo9 per L and the platelet increment was less than 100 percent, or 3) if there was deterioration in the neurologic status. Patients who responded were then treated with PE three times during the next week and twice during the subsequent week. Patients who responded partially were treated with PE five times over the next 7 days. Patients who did not respond started the protocol again. Blood samples were taken before the first PE (to establish pretreatment values), before each procedure, and at the end of the cycle (Days 7-9), and various analyses were carried out as follows. Immune complexes were determined centrally using three methods: polyethylene glyc01,~lZI-Clq (Clq)?and Raji cell assay.4 Measurement of 6keto-prostaglandin F,a was done by radioimmunoassay in which gammaglobulin and antiserum were added to the prostaglandin Flu.’ Platelet-agglutinating factor (PAF)was determined according to the method of Kelton et a1.6 by mixing serotoninlabeled platelets and a solution containing the large multimers of von Willebrand factor (vWF) with the patient’s serum and then observing for visible aggregates. The presence of plateletspecific antibody was determined by a direct immunoradiometric assay according to Kelton’s published method.’ Total vWF antigen (vWF:Ag) was measured by a modified Laurel1 technique with a polyclonal rabbit antibody against a standard reference plasma.s Factor VIII (FVIII) multimers were evaluated by a modification of the method of Ruggeri et aL9
and identified on the electroblot by an alkaline phosphatase immunochemical staining system. While early work involved the use of proteolytic inhibitors to protect against possible multimer degradation, we found this precaution to be unnecessary and to have no effect on the patterns. Therefore, subsequent samples were collected and rapidly frozen until assay.
Results Of the 33 patients ineligible for the randomized trial, 24 could not be entered into the cohort because of significant oliguria or problems related to fluid retention (cardiac congestion). A diagnosis of HUS was made initially for three of these oliguric patients who had only moderate thrombocytopenia. Nine patients did not enter the trial, on their own or their doctors’ refusal to consent. The group of patients with renal compromise included 12 men and 12 women. The mean age was 46.9 years (range, 15-77). The presenting features and the response to treatment of each patient are shown in Table 1. The mean hemoglobin was 91.9 g per L, and there was an elevated reticulocyte count in 18 of the 22 patients tested. The average platelet count at the time of presentation was 35.5 x lo9 per L, with 11 (46%) subjects having counts below 20 x lo9 per L. At presentation, only six patients had significant fever (temperatures in excess of 38.5”C), and 16 patients (67%) had a history of focal neurologic signs or symptoms. The creatinine level was elevated in 100 percent, the blood urea nitrogen was elevated in 92 percent, and the lactate dehydrogenase
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PLASMA EXCHANGE IN TTP
1992-Vol. 32, No. 8
in 100 percent. PE procedures were carried out an average of 13.2 times per patient. As shown in Table 2, at the time of presentation, platelet antibody measurements indicated the presence of increased levels of IgG on the platelets in 16 of 19 patients (5 were not tested). The 6-keto-prostaglandin F,a was abnormal in the majority of patients; however, it was increased in 6 and decreased in 5 of the 16 patients tested. In at least one of the three tests done, immune complexes were detected in the serum of all of the patients tested at the time of presentation: the Raji cell assay gave positive results in 9 of 20 tests, polyethylene glycol did so in 15 of 21 tests, and Clq did so in 15 of 19 tests. PAF was present in the serum of 9 of 15 patients tested. The total vWF:Ag was markedly increased (mean value, 438%) in all of the 12 patients assessed, but the multimeric pattern was multimeric forms variable. Very high-molecular-weight 0 of FVIII were not present in any of the seven patients from whom samples were available: normal patterns were seen in six of these patients, and one had reduced amounts of HMW material. A complete response to PE (as indicated by a rise in the platelet count to > 150 x lo9 per L 1 week after initiation of treatment and the absence of new neurologic signs and symptoms) was seen in 12 of the 24 patients. Although further PE was required in three of these patients because of recurrence of thrombocytopenia, all of these 12 patients survived and became free of any sign of TTP. All patients who survived regained normal renal function. A partial response to treatment (defined as an increase in the platelet count to at least twice the count before treatment but remaining below 150 x 109L) was seen in three additional patients. Of the remaining nine patients, one died and eight were judged to have experienced treatment failure at 1 week. Five patients who experienced treatment failure subsequently did respond to treatment. In our study protocol, patients who experienced treatment failure at the l-week evaluation time could be managed, at that point, at the discretion of the attending physician. For all of these eight patients, the choice was made to continue PE, and it was during the period of further exchange that the patients’ responses occurred. Of the total of 24 patients, one died during the initial week of PE therapy and three others died approximately 1 month after initiation of treatment, one while still receiving PE.
Discussion In this series of patients with hemolytic anemia, thrombocytopenia, and renal involvement, the classic features of TTP were not seen consistently: fever was present in only 25 percent of the patients, but 67 percent had a history of focal neurologic signs or symptoms. A similar heterogeneity of presentation was seen in the 102 patients with ‘ITP and minimal or no renal involvement who were entered into our randomized study.’ These findings raise the question of whether fever should continue to be included as a typical feature of TTP. As the frequency of neurologic signs or symptoms was also lower than that in other reported series, it is possible that the earlier detection of the disorder in our study prevented the evolution to a more complete clinical presentation, The heterogeneity of presentation of our patients reflects that reported in the literature.l0
713
Although, in children, HUS is probably a distinct syndrome related to infection by verotoxin-producing organisms,” it is rare in adults. ?Tp is defined as having “a triad (thrombocytopenia, microangiopathic hemolytic anemia, and neurologic dysfunction) or often pentad (triad plus fever and renal dysfunction) of clinical findi n g ~ . ” ~ ~However, @ ~ ~ ~no~ documented ) specific degree of renal impairment is cited as a criterion for the diagnosis of HUS in an adult. George and Aster stated that HUS is similar to lTP, “but differing from it in that renal failure is more p r ~ m i n e n t . ” ’ ~ ( P ’ ~Rather ~~) than viewing patients with diagnostic features of TTP and prominent renal involvement as having a different disease, we consider it more likely that they are at one end of a spectrum of renal involvement that is part of l T P. Overall, oliguria sufficiently severe to preclude treatment with plasma infusion was present in 24 (18%)of the 135 patients considered for entry into our randomized clinical trial comparing plasma infusion and PE in TTP. Thus, for many patients, PE is the only treatment that will allow them to receive plasma. In most reported series of patients with TTP,lo the patients received a variety of treatments, and it is difficult to assess the likelihood that any one treatment produced a successful outcome. All 24 patients reported in the present article were treated in a standardized fashion with acetylsalicylic acid, dipyridamole, and PE. Fifteen of the 24 patients had a complete or partial response within 7 days. Five other patients eventually responded, all with continued PE. Thus, the treatment used produced an early or an eventually successful outcome in 20 (83%)of 24 patients. This success rate was very similar to that found in our randomized study, in which patients receiving PE had response rates of 47 percent at the end of the first treatment cycle and 78 percent at 6 months.’ Thus, even in patients with what could be considered a more severe form of disease, PE appears to be of benefit in the treatment of TTP. In this series of patients with ‘ITP, there was great heterogeneity in the levels of factors thought to be implicated in the pathogenesis of lTP. There was no correlation among disease severity at presentation, the level of any putative pathogenic factor, and the final outcome. Most of the patients tested (16/19) had IgG on the surface of their platelets, which is consistent with the presence of either antibody or immune complexes on the platelets. This finding is in keeping with previous reports of platelet antibodies or immune complexes in TTP.13J4 In the present study, immune complexes were detectable in every patient by at least one of three methods used. However, the presence of immune complexes was not always associated with the presence of platelet antibody as measured by the direct immunoradiometric assay. The relationship between the immune complexes and platelet
714
ROCK ET AL.
antibodies is not yet clear but is the subject of continuing investigation.Is The only consistent laboratory abnormality was the finding, in every one of the 11 patients in whom it was measured, of increased vWF:Ag. However, the quantity of the HMW FVIII multimers was normal. Previous work has implicated these HMW multimers in the pathogenesis of disease, which suggests that the presence of HMW forms is related to enhanced platelet aggregati~n.'~ PAF, another factor thought to be associated with the presence of platelet clumps in T"P,'6 was not found in 40 percent of the patients and, even when present, did not appear to predict outcome or the level of any other biochemical marker. The present study indicates that the combination of PE and anti-platelet drugs is often effective treatment of 'ITP even when the disease has produced significant renal impairment. The study also indicates that, as yet, there is no consistent biochemical marker or markers that can be correlated with disease severity or that can predict outcome. Although the levels of vWF were elevated in most if not all patients, perhaps as a reflection of endothelial cell trauma, the heterogeneity of the multimeric patterns makes it impossible to determine the specific role, if any, of vWF in this disease.
Acknowledgments The authors gratefully acknowledge the assistance of Pauline Tittley and Doug Palmer, Canadian Red Cross Blood Transfusion Service; Dr. Jack Gauldie and Jan Santos, McMaster University; and Carole Hubert and the apheresis nurses at the Canadian Apheresis Study Group centers.
References 1 . Rock GA, Shumak KH, Buskard NA, et al. Comparison of plasma
2. 3.
4. 5.
6. 7.
8.
exchange with plasma infusion in the treatment of thrombotic thrombocytopenic purpura. Canadian Apheresis Study Group. N Engl J Mcd 1991;325:393-7. Rayner AA, Steele G Jr, Rodrick ML, et al. Application of polyethylene glycol turbidity assay to detection of circulating immune complexes in cancer patients. Am J Surg 1981;141:460-4. Zubler RH, Lange G, Lambert PH, Micscher PA. Detection of immune complexes in unheated sera by modified l'I-Clq binding test. Effect of heating on the binding of Clq by immune complexes and application of the test to systemic lupus erythematosus. J lmmunol 1976;116:232-5. Williams RC Jr. Immune complexes in clinical and experimental medicine. Cambridge, MA: Harvard University Press, 1980. Blachman MA, Senyi AF, Hirsh J, Surya Y. Buchanan M, Mustard JF. Shortening of the bleeding time in rabbits by hydrocortisone caused by inhibition of prostacyclin generation by the vessel wall. J Clin Invest 1979;63:1026-35. Kelton JG, Moore J, Santos A, Sheridan D. The detection of a platelet-agglutinating factor in thrombotic thrombocytopenic purpura. Ann Intern Med 1984;101:589-93. Kelton JG, Powers PJ, Carter CJ. A prospective study of the usefulness of the measurement of platelet-associated IgG for the diagnosis of idiopathic thrombocytopenic purpura. Blood 1982;60: 1050-3. Laurell CB. Quantitative estimation of proteins by electrophoresis
9.
10. 11.
12.
13. 14.
15. 16.
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in agarose gel containing antibodies. Anal Biochcm 1966;15:4552. Ruggcri ZM, Mannucci PM, Lombardi R, Fcderici AB. Zimmerman TS. Multimeric composition of factor VIIl/von Willebrand factor following administration of DDAVP: implications for pathophysiology and therapy of von Willebrand's disease subtypes. Blood 1982;59:1272-8. Ridolfi RL, Bell WR. Thrombotic thrombocytopcnic purpura. Rcport of 25 cases and review of the literature. Medicine (Baltimore) 1981;60:4 13-28. Karmali MA, Petric M, Lim C, Fleming PC, Arbus G S , Lier H. The association between idiopathic hemolytic uremic syndrome and infection by verotoxin-producing Escherichia coli. J Infect Dis 1985;151:775-82. George IN, Aster RH. Thrombocytopenia due to enhanced platelet destruction by nonimmunologic mechanisms. In: Williams WJ, ed. Hematology. 4th ed. New York: McGraw-Hill, 1990:135169. Morrison J, McMillan R. Elevated platelet-associated IgG in thrombotic thrombocytopenic purpura. JAMA 1977;238: 1944-5. Zimmerman SE, Smith FP, Phillips TM, Coffey RJ, Schein PS. Gastric carcinoma and thrombotic thrombocytopenic purpura: association with plasma immune complex concentrations. Br Med J (Clin Res Ed) 1982;284:1432-4. Tandon NN, Jamieson GA, Rock GA. Identification of antibodies against GPIV (CD36) in the sera of TTP patients. Blood 1991;78:Suppl:186A. Kelton JG, Moore JC, Murphy WG. Studies investigating platelet aggregation and release initiated by sera from patients with thrombotic thrombocytopenic purpura. Blood 1987;69:924-8.
Gail A. Rock, PhD, MD, Associate Professor, Departments of Medicine, Pathology, and Biochemistry, University of Ottawa, Ottawa, Ontario, Canada; 206-435 St. Laurent Blvd, Ottawa, ON K1K 228, Canada. [Reprint requests] Kenneth H. Shumak, MD, Professor, Department of Medicine, University of Toronto, Toronto, ON. Canada. John G. Kelton, MD, Professor, Departments of Medicine and Pathology, McMaster University, Hamilton, ON, Canada. Victor S. Blanchette, MD, Associate Professor, Department of Pediatrics, University of Toronto. Noel A. Buskard, MD, Professor, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada. Rama C. Nair, PhD, Professor, Department of Epidemiology, University of Ottawa. Robert A. Spasoff, MD, Professor, Department of Epidemiology, University of Ottawa. Members of the Canadian Apheresis Study Group include: B John's: Grenfell B. Adams, MD Vancouver: Barrett W. Benny, MD; Noel A. Buskard, MD Saskafoon: Robert T. Card, MD London: William F. Clark, MD Kingston: Peter M. Ford, MD Edmonton: Philip A. Gordon, MD Montrial: Max Katz, MD Calgary: John Klassen, MD Quibec: Pierre F. Leblond, MD Sherbrooke: Marriette Lepine-Martin, MD Hamilton: John A. McBride, MD; Marion S. Stcrnbach, MD Ottawa: W. Philip Mickelson, MD; Rama C. Nair, PhD; Gail A. Rock, PhD, MD; Robert A. Spasoff, MD Victoria: Harry L. Rayner, MD Toronto: Kenneth H. Shumak, MD; David M.C. Sutton, MD
%
Abbrevlations: C l q = l W C l q Immune complex test; FVlll = factor VIII; HMW = hlgh molecular weight; HUS = hemolytlc uremic syndrome; PAF = piatelet-agglutlnatlng factor; PE = plasma exchange; :TTP = thrombotic thrombocytopenlc purpura; vWF:Ag = von Willebrand factor antlgen.
plasma infusion and PE therapy in 7TP, the Canadian Apheresis Study Group undertook a multi-center, randomized, prospective trial of these treatments from 1983 through 1989. All patients with 'ITP at 16 participating centers across Canada were considered for the study. The study showed that PE i s more effective than plasma infusion in the treatment of TTP.' The eligibility criteria for patients to be included i n this trial were a platelet count of less than 100 x lo9 per L, microangiopathic hemolytic anemia, and no other cause for thrombocytopenia or microangiopathic hemolytic anemia. Because these patients might be randomly assigned to receive plasma infusion, an additional criterion for eligibility was that a patient be considered able to tolerate the fluid load of plasma infusion. Patients with congestive heart failure or severe oliguria were
CURRENT TREATMENT OF PATIENTS with thrombotic usually includes plasma thrombocytopenic purpura (") therapy, either as infusion of fresh-frozen plasma or as plasma exchange (PE) using fresh-frozen plasma as the replacement fluid. In addition, anti-platelet drugs are commonly employed. To compare the effectiveness of From the Departments of Medicine, Pathology, Epidemiology, and Biochemistry, University of Ottawa, Ottawa, Ontario; the Departments of Medicine and Pediatrics, University of Toronto, Toronto, Ontario; the Department of Pathology, McMaster University, Hamilton, Ontario; and the Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada. Supported in part by the Canadian National Health Research Dcvelopment Program, National Health & Welfare, Canada Grant No. 6613-1158 (JK). Rcceived for publication September 5, 1991; revision received March 17, 1992, and accepted April 2, 1992.
710
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1992-Vol. 32. No. 8
Table 1.
Features at presentation and response to treatment in 24 patients with 77P* and oliguria At presentation
Platelet countt Hb* BUNS Creatinines ( x loe/L) (gL)(pmolR) (pmol/L)
Fever7 (OC)
FNA"
Patient ID Code
1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18 19 20 21 22 23 24
20 10 35 120 33 70 13 27 14 56 20 51 21 19 34 10 29 13 88 42 61 11 16 17
104 92 84 76 106 94 102 81 90 92 69 NT
73 118 119 81 90 92 74 94 101 103 108 71
27.8 22.8 42.0 7.9 34.8 26.7 42.1 28.2 29.4 37.4 38.2 16.8 9.7 8.8 29.3 26.5 13.3 11.1 51.6 21.6 15.1 17.2 24.0 18.6
203 156 398 168 690 187 884 371 591 138 946 245 124 149 424 333 206 195 815 199 278 128 378 145
-
+ -38.7 -
-
-
+ (38.5) + (38.5) + (38.7) -
-
-
+ + + + +
+
+ -
+
-
+ (38.5) + + + (38.5) +
Thrombotic thrombocytopenlc purpura.
*Q
+ + + + +
t Normal range, 150400 x 100 per L. Hemoglobin; normal range, 120-175 g per L Blood urea nitrosen; normal range, 1.8-8.2m o l per L. II Normal range, 46-110 pmol per 11 Normal, 37.0"C; - = condition not present; + = condition present. ** Focal neurologic abnormalities; normal, - .
L.
therefore considered ineligible. A total of 102 patients were recruited into the trial, but, in addition, data were collected on 33 other patients who were not randomly assigned. Of these 33, 24 did not meet the eligibility criteria because of renal dysfunction. This group of patients with renal dysfunction represents a category separate from those in our randomized trial.' The renal involvement could lead some to diagnose these patients as having hemolytic uremic syndrome (HUS); certainly, if considered to have TI", these patients could be said to have a more aggressive form of the disease than those with normal renal function. The present report describes the clinical and laboratory presentation and the outcome in these 24 patients with 'ITP and shows that, even in a severe form of disease, PE can be an effective treatment. Materials and Methods Patients considered for eligibility for entry into the randomized trial were first identified by the treating physician as having TIT. The randomization center was then contacted and the center verified that the patient had thrombocytopenia (a platelet
After treatment History RBC of T T P t t fragments**
NT NT NT -
-
-
-
Platelet Reticulocyte count count§§ Outcome11 II ( x lO'/L)
+ + + + + + + + + + + + + + + + + + + + + + +
tt Normal, -. Red cell fragments; normal,
**§I
Elev Elev Elev Elev Elev Elev Norm Elev Elev Elev NT Elev Elev Norm Norm Elev NT Elev Elev Elev Elev Elev Elev Norm
R PR F
R R R R R R F PR F F R D R F F R R
R PR F F
200 94 45 208 186 195 374 195 254 71 139 20 10 265 D
269 30 20 334 21 1 202 142 20 15
+.
Elev = elevated; Norm = normal; NT = not tested. 11 11 Assessed on Day 7 of treatment on the basis of the platelet count: R = response; PR = partial response; F = treatment failure: D = death.
count < 100 x 109/L) with microangiopathic hemolytic anemia. Any other identifiable cause for these findings led to ineligibility, as did any history of congestive heart failure or anuria that, in the opinion of the attending physician, would render the patient unable to tolerate plasma infusion. Patients considered ineligible for the randomized trial because of oliguria are the subject of the present report. Blood counts were measured by the method of choice at each participating hospital. All other tests were done centrally on appropriate samples; the specimens for platelet-specific antibody were sent by courier for testing within 24 hours of collection. Patients were treated with daily PE (1.5 X plasma volume) for the first 3 days and then single-volume PE to a total of seven exchanges within 9 days of starting treatment. Patients were also given dipyridamole (400 mg/day) and acetylsalicylic acid (325 mglday) orally. Fresh-frozen plasma was used for replacement in all cases. We assessed patients after seven procedures (between Days 7 and 9) and classified them as having responded fully, having responded partially, or having failed to respond. Outcome was determined according to the absolute platelet count, the platelet increment, and the neurologic status of the patient. We defined a complete response as an improvement in the platelet count to greater than 150 x lo9 per L on at least two consecutive days and no new neurologic events.
712
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ROCK ET AL. Table 2.
Patlent
ID code
vWF:Agt
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
NT NT NT NT NT NT NT NT
Putative pathogenic factors in 24 patients with 77P* and oliguria
Factor Vlll multimers*
Raji cell
(titer)§
NT NT NT NT NT NT NT NT NT NT NT NT Decr NT NT Norm Norm Norm Norm Norm NT NT NT NT
525 248 352 300 264 183
NT 300 1390 420 360 520
NT NT NT NT
64 -
-
32 32 128 128 -
-
32 64 64 32
NT NT NT NT
* Thrombotic thrombocytopenic purpura.
t Von Willebrand factor:antigen; normal, 40-150; NT
* Norm normal: Decr Normal, negative =
=
decreased.
=
not tested.
Immune complexes PEG (pt.lNpool)ll
Platelet antibody
c1qll
DIRMAii
(fglplt)
PAFtt
1.98 4.64 0.82 0.59 1.10 1.07 2.77 3.28 2.66 2.39 0.89 2.90 0.89 0.78 2.11 9.66 1.09 1.74 1.46 8.29
0.9 1.2 0.6 1.4 1.1 0 1.1 1.1 4.8 0 0 13.2 10.4 26.0
6.7 27.6
-
NT
NT
NT
NT
7.2 2.4 3.9 0 1.1
14.6 7.1 10.4
NT NT
NT NT NT NT
0.50
NT
(“w
-
6.2 13.0 2.3 16.0 4.7 7.9 3.9 8.0 7.0
NT
NT
-
13.1
NT 6.0 72.2 26.2
NT 23.2
-
+ + + + + +
NT NT
+ + +
NT NT NT NT NT
7 lZ5l= Clq assay: normal, 0. i i Direct immunoradiometric assay; normal, 5.5 fg per platelet. tt Platelet-aggutinating factor: normal, negative (-).
(-).
§
11 Polyethylene glycol test (patient platelets compared to normal pool): normal, 1 .
A partial response was defined as a platelet count between 50 and 150 x lo9 per L with a platelet increment of greater than 100 percent and no new neurologic events. We considered patients to have failed to respond 1) if the platelet count was less than 50 x lo9 per L, 2) if the platelet count was less than 100 x lo9 per L and the platelet increment was less than 100 percent, or 3) if there was deterioration in the neurologic status. Patients who responded were then treated with PE three times during the next week and twice during the subsequent week. Patients who responded partially were treated with PE five times over the next 7 days. Patients who did not respond started the protocol again. Blood samples were taken before the first PE (to establish pretreatment values), before each procedure, and at the end of the cycle (Days 7-9), and various analyses were carried out as follows. Immune complexes were determined centrally using three methods: polyethylene glyc01,~lZI-Clq (Clq)?and Raji cell assay.4 Measurement of 6keto-prostaglandin F,a was done by radioimmunoassay in which gammaglobulin and antiserum were added to the prostaglandin Flu.’ Platelet-agglutinating factor (PAF)was determined according to the method of Kelton et a1.6 by mixing serotoninlabeled platelets and a solution containing the large multimers of von Willebrand factor (vWF) with the patient’s serum and then observing for visible aggregates. The presence of plateletspecific antibody was determined by a direct immunoradiometric assay according to Kelton’s published method.’ Total vWF antigen (vWF:Ag) was measured by a modified Laurel1 technique with a polyclonal rabbit antibody against a standard reference plasma.s Factor VIII (FVIII) multimers were evaluated by a modification of the method of Ruggeri et aL9
and identified on the electroblot by an alkaline phosphatase immunochemical staining system. While early work involved the use of proteolytic inhibitors to protect against possible multimer degradation, we found this precaution to be unnecessary and to have no effect on the patterns. Therefore, subsequent samples were collected and rapidly frozen until assay.
Results Of the 33 patients ineligible for the randomized trial, 24 could not be entered into the cohort because of significant oliguria or problems related to fluid retention (cardiac congestion). A diagnosis of HUS was made initially for three of these oliguric patients who had only moderate thrombocytopenia. Nine patients did not enter the trial, on their own or their doctors’ refusal to consent. The group of patients with renal compromise included 12 men and 12 women. The mean age was 46.9 years (range, 15-77). The presenting features and the response to treatment of each patient are shown in Table 1. The mean hemoglobin was 91.9 g per L, and there was an elevated reticulocyte count in 18 of the 22 patients tested. The average platelet count at the time of presentation was 35.5 x lo9 per L, with 11 (46%) subjects having counts below 20 x lo9 per L. At presentation, only six patients had significant fever (temperatures in excess of 38.5”C), and 16 patients (67%) had a history of focal neurologic signs or symptoms. The creatinine level was elevated in 100 percent, the blood urea nitrogen was elevated in 92 percent, and the lactate dehydrogenase
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PLASMA EXCHANGE IN TTP
1992-Vol. 32, No. 8
in 100 percent. PE procedures were carried out an average of 13.2 times per patient. As shown in Table 2, at the time of presentation, platelet antibody measurements indicated the presence of increased levels of IgG on the platelets in 16 of 19 patients (5 were not tested). The 6-keto-prostaglandin F,a was abnormal in the majority of patients; however, it was increased in 6 and decreased in 5 of the 16 patients tested. In at least one of the three tests done, immune complexes were detected in the serum of all of the patients tested at the time of presentation: the Raji cell assay gave positive results in 9 of 20 tests, polyethylene glycol did so in 15 of 21 tests, and Clq did so in 15 of 19 tests. PAF was present in the serum of 9 of 15 patients tested. The total vWF:Ag was markedly increased (mean value, 438%) in all of the 12 patients assessed, but the multimeric pattern was multimeric forms variable. Very high-molecular-weight 0 of FVIII were not present in any of the seven patients from whom samples were available: normal patterns were seen in six of these patients, and one had reduced amounts of HMW material. A complete response to PE (as indicated by a rise in the platelet count to > 150 x lo9 per L 1 week after initiation of treatment and the absence of new neurologic signs and symptoms) was seen in 12 of the 24 patients. Although further PE was required in three of these patients because of recurrence of thrombocytopenia, all of these 12 patients survived and became free of any sign of TTP. All patients who survived regained normal renal function. A partial response to treatment (defined as an increase in the platelet count to at least twice the count before treatment but remaining below 150 x 109L) was seen in three additional patients. Of the remaining nine patients, one died and eight were judged to have experienced treatment failure at 1 week. Five patients who experienced treatment failure subsequently did respond to treatment. In our study protocol, patients who experienced treatment failure at the l-week evaluation time could be managed, at that point, at the discretion of the attending physician. For all of these eight patients, the choice was made to continue PE, and it was during the period of further exchange that the patients’ responses occurred. Of the total of 24 patients, one died during the initial week of PE therapy and three others died approximately 1 month after initiation of treatment, one while still receiving PE.
Discussion In this series of patients with hemolytic anemia, thrombocytopenia, and renal involvement, the classic features of TTP were not seen consistently: fever was present in only 25 percent of the patients, but 67 percent had a history of focal neurologic signs or symptoms. A similar heterogeneity of presentation was seen in the 102 patients with ‘ITP and minimal or no renal involvement who were entered into our randomized study.’ These findings raise the question of whether fever should continue to be included as a typical feature of TTP. As the frequency of neurologic signs or symptoms was also lower than that in other reported series, it is possible that the earlier detection of the disorder in our study prevented the evolution to a more complete clinical presentation, The heterogeneity of presentation of our patients reflects that reported in the literature.l0
713
Although, in children, HUS is probably a distinct syndrome related to infection by verotoxin-producing organisms,” it is rare in adults. ?Tp is defined as having “a triad (thrombocytopenia, microangiopathic hemolytic anemia, and neurologic dysfunction) or often pentad (triad plus fever and renal dysfunction) of clinical findi n g ~ . ” ~ ~However, @ ~ ~ ~no~ documented ) specific degree of renal impairment is cited as a criterion for the diagnosis of HUS in an adult. George and Aster stated that HUS is similar to lTP, “but differing from it in that renal failure is more p r ~ m i n e n t . ” ’ ~ ( P ’ ~Rather ~~) than viewing patients with diagnostic features of TTP and prominent renal involvement as having a different disease, we consider it more likely that they are at one end of a spectrum of renal involvement that is part of l T P. Overall, oliguria sufficiently severe to preclude treatment with plasma infusion was present in 24 (18%)of the 135 patients considered for entry into our randomized clinical trial comparing plasma infusion and PE in TTP. Thus, for many patients, PE is the only treatment that will allow them to receive plasma. In most reported series of patients with TTP,lo the patients received a variety of treatments, and it is difficult to assess the likelihood that any one treatment produced a successful outcome. All 24 patients reported in the present article were treated in a standardized fashion with acetylsalicylic acid, dipyridamole, and PE. Fifteen of the 24 patients had a complete or partial response within 7 days. Five other patients eventually responded, all with continued PE. Thus, the treatment used produced an early or an eventually successful outcome in 20 (83%)of 24 patients. This success rate was very similar to that found in our randomized study, in which patients receiving PE had response rates of 47 percent at the end of the first treatment cycle and 78 percent at 6 months.’ Thus, even in patients with what could be considered a more severe form of disease, PE appears to be of benefit in the treatment of TTP. In this series of patients with ‘ITP, there was great heterogeneity in the levels of factors thought to be implicated in the pathogenesis of lTP. There was no correlation among disease severity at presentation, the level of any putative pathogenic factor, and the final outcome. Most of the patients tested (16/19) had IgG on the surface of their platelets, which is consistent with the presence of either antibody or immune complexes on the platelets. This finding is in keeping with previous reports of platelet antibodies or immune complexes in TTP.13J4 In the present study, immune complexes were detectable in every patient by at least one of three methods used. However, the presence of immune complexes was not always associated with the presence of platelet antibody as measured by the direct immunoradiometric assay. The relationship between the immune complexes and platelet
714
ROCK ET AL.
antibodies is not yet clear but is the subject of continuing investigation.Is The only consistent laboratory abnormality was the finding, in every one of the 11 patients in whom it was measured, of increased vWF:Ag. However, the quantity of the HMW FVIII multimers was normal. Previous work has implicated these HMW multimers in the pathogenesis of disease, which suggests that the presence of HMW forms is related to enhanced platelet aggregati~n.'~ PAF, another factor thought to be associated with the presence of platelet clumps in T"P,'6 was not found in 40 percent of the patients and, even when present, did not appear to predict outcome or the level of any other biochemical marker. The present study indicates that the combination of PE and anti-platelet drugs is often effective treatment of 'ITP even when the disease has produced significant renal impairment. The study also indicates that, as yet, there is no consistent biochemical marker or markers that can be correlated with disease severity or that can predict outcome. Although the levels of vWF were elevated in most if not all patients, perhaps as a reflection of endothelial cell trauma, the heterogeneity of the multimeric patterns makes it impossible to determine the specific role, if any, of vWF in this disease.
Acknowledgments The authors gratefully acknowledge the assistance of Pauline Tittley and Doug Palmer, Canadian Red Cross Blood Transfusion Service; Dr. Jack Gauldie and Jan Santos, McMaster University; and Carole Hubert and the apheresis nurses at the Canadian Apheresis Study Group centers.
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in agarose gel containing antibodies. Anal Biochcm 1966;15:4552. Ruggcri ZM, Mannucci PM, Lombardi R, Fcderici AB. Zimmerman TS. Multimeric composition of factor VIIl/von Willebrand factor following administration of DDAVP: implications for pathophysiology and therapy of von Willebrand's disease subtypes. Blood 1982;59:1272-8. Ridolfi RL, Bell WR. Thrombotic thrombocytopcnic purpura. Rcport of 25 cases and review of the literature. Medicine (Baltimore) 1981;60:4 13-28. Karmali MA, Petric M, Lim C, Fleming PC, Arbus G S , Lier H. The association between idiopathic hemolytic uremic syndrome and infection by verotoxin-producing Escherichia coli. J Infect Dis 1985;151:775-82. George IN, Aster RH. Thrombocytopenia due to enhanced platelet destruction by nonimmunologic mechanisms. In: Williams WJ, ed. Hematology. 4th ed. New York: McGraw-Hill, 1990:135169. Morrison J, McMillan R. Elevated platelet-associated IgG in thrombotic thrombocytopenic purpura. JAMA 1977;238: 1944-5. Zimmerman SE, Smith FP, Phillips TM, Coffey RJ, Schein PS. Gastric carcinoma and thrombotic thrombocytopenic purpura: association with plasma immune complex concentrations. Br Med J (Clin Res Ed) 1982;284:1432-4. Tandon NN, Jamieson GA, Rock GA. Identification of antibodies against GPIV (CD36) in the sera of TTP patients. Blood 1991;78:Suppl:186A. Kelton JG, Moore JC, Murphy WG. Studies investigating platelet aggregation and release initiated by sera from patients with thrombotic thrombocytopenic purpura. Blood 1987;69:924-8.
Gail A. Rock, PhD, MD, Associate Professor, Departments of Medicine, Pathology, and Biochemistry, University of Ottawa, Ottawa, Ontario, Canada; 206-435 St. Laurent Blvd, Ottawa, ON K1K 228, Canada. [Reprint requests] Kenneth H. Shumak, MD, Professor, Department of Medicine, University of Toronto, Toronto, ON. Canada. John G. Kelton, MD, Professor, Departments of Medicine and Pathology, McMaster University, Hamilton, ON, Canada. Victor S. Blanchette, MD, Associate Professor, Department of Pediatrics, University of Toronto. Noel A. Buskard, MD, Professor, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada. Rama C. Nair, PhD, Professor, Department of Epidemiology, University of Ottawa. Robert A. Spasoff, MD, Professor, Department of Epidemiology, University of Ottawa. Members of the Canadian Apheresis Study Group include: B John's: Grenfell B. Adams, MD Vancouver: Barrett W. Benny, MD; Noel A. Buskard, MD Saskafoon: Robert T. Card, MD London: William F. Clark, MD Kingston: Peter M. Ford, MD Edmonton: Philip A. Gordon, MD Montrial: Max Katz, MD Calgary: John Klassen, MD Quibec: Pierre F. Leblond, MD Sherbrooke: Marriette Lepine-Martin, MD Hamilton: John A. McBride, MD; Marion S. Stcrnbach, MD Ottawa: W. Philip Mickelson, MD; Rama C. Nair, PhD; Gail A. Rock, PhD, MD; Robert A. Spasoff, MD Victoria: Harry L. Rayner, MD Toronto: Kenneth H. Shumak, MD; David M.C. Sutton, MD
