Early Versus Late Therapeutic Plasma Exchange for Thrombotic Microangiopathy –Comparison of Hospitalization Outcomes in United States
Authors: Guru Murthy Guru Subramanian , Venkitachalam Raji , Dhakal Ishwori , Mehta Paulette 
Published: October 2019

Abstract

Background:
Therapeutic plasma exchange (TPE) is used in the treatment of thrombotic microangiopathy (TMA). For several reasons, the timing of initiation of TPE in patients with TMA admitted to the hospital varies greatly. In this study, we have aimed to retrospectively compare the short term outcomes, costs and in-hospital mortality of early versus late TPE in patients with TMA admitted to US hospitals.
Methods:
Using Nationwide Inpatient Sample database, we identified all hospital discharges related to TMA as the primary diagnosis and TPE as the primary procedure from 2007 through 2011. ICD 9 codes were used to identify the diagnosis and procedure related information. Data on patient demographics, day of initiation of TPE, length of stay (LOS), cost of hospitalization and deaths were obtained. Patients were divided into early TPE (day 0 or day 1 of hospital admission) and late TPE groups (beyond day 1 of admission). Comparison of outcomes was also made for patients who were initiated on TPE at day 0 versus day 1 of admission. Outcomes were described using descriptive statistics and analyzed using Mann Whitney U test and Chi -square test. Multivariate logistic regression method was used to determine the factors associated with mortality.
Results:
Based on sample weights, an estimated 3823 patient discharges were identified nationwide between 2007-2011 with TMA as the primary diagnosis and TPE as the primary procedure. Patients had a median age of 46 years in early TPE and 47 years in late TPE group. Baseline characteristics of the study group are summarized in Table 1. Mean LOS was 11.69±0.17 days in the early TPE group versus 15.97±0.37 days in the late TPE group (p=0.01). Mean cost of hospitalization was $ 128226.51±2482.66 in the early TPE group versus $ 170909.05±6638.03 in late TPE group (p < 0.01). In-hospital mortality was 4.2% (n=124) in the early TPE group versus 7.2% (n=60) in the late TPE group (p =0.01). On comparing the outcomes between initiation of TPE on day 0 versus day 1 of hospitalization, no significant differences were noted in mean LOS (11.76±0.25 days in TPE day 0 group vs 11.62±0.23 days in TPE day 1 group, p=0.44), cost ($129865.23±3799.70 in TPE day 0 group vs $126442.55±3127.68 in TPE day 1, p=0.36), and mortality (TPE day 0 = 4% vs TPE day 1 = 4.3%, p=0.82). On multivariate analysis, initiation of TPE on day 0 or day 1 was associated with reduced mortality (OR 0.55, CI 0.40-0.76, p <0.01) as compared to TPE initiated after day 1, whereas age > 50 years (OR 4.37, CI 3.13-6.08, p<0.01) was associated with higher mortality.
Conclusions:
Early TPE for TMA significantly reduces the in-hospital mortality, hospitalization cost and LOS as compared to those who received late TPE. However, these outcomes did not differ significantly when comparing TPE initiation on day 0 versus day 1 of hospital admission. Hence, undue delays in initiation of TPE should be avoided in patients with TMA in order to improve their outcome.
Table 1: Baseline study characteristics Variable Early TPE (n=2995) Late TPE (n=828) P value Median Age in years (range) 46 (10-90) 47 (9-85) 0.03* Sex Males Females Missing 989 1995 11 254 574 0 0.20 Race Whites Blacks Others Missing 1248 1058 400 289 325 367 76 60 0.01* Insurance status Medicare Medicaid Private Others Missing 584 616 1335 441 19 216 155 325 127 5 0.01* Admission day Weekend Weekday 616 2379 169 659 0.96
*p <0.05-significant

Disclosures
No relevant conflicts of interest to declare.