# A Retrospective Analysis of ADAMTS13 Enzymatic Activity Results in a Population With Thrombotic Thrombocytopenic Purpura Disease in the Arabian Gulf and Colombia (APOLO Study)

## TL;DR

This study analyzed ADAMTS13 enzyme activity in TTP patients from the Arabian Gulf and Colombia, finding significant regional differences in result turnaround times.

## Contribution

The study provides new insights into ADAMTS13 activity levels and diagnostic delays in TTP patients from two distinct geographic regions.

## Key findings

- Severe ADAMTS13 deficiency (<10%) was found in 23.3% of samples, indicating TTP.
- Turnaround time for results was significantly longer in the Arabian Gulf compared to Colombia.
- The median age of TTP patients in the study was 39 years, consistent with global reports.

## Abstract

Little is known about the thrombospondin type-1 motif, member 13 (ADAMTS-13) enzymatic activity in subjects with suspected/confirmed thrombotic thrombocytopenic purpura (TTP) in the Arabian Gulf and Colombia. The retrospective analysis of ADAMTS13 enzymatic activity results in a population with thrombotic thrombocytopenic purpura disease in the Arabian Gulf and Colombia (APOLO study) aimed to report on ADAMTS-13 enzymatic activity, subject demographics, and the turnaround time for results. This study used laboratory analyses of ADAMTS-13 enzymatic activity in blood samples from subjects with suspected/confirmed TTP in the Arabian Gulf (N=235) and in Colombia (N=155). The primary objective was to report ADAMTS-13 enzymatic activity levels and distribution in categories: severe deficiency <10% (TTP diagnosis), borderline activity 10-20%, and no deficiency >20%. Descriptive statistics were performed using SAS 9.4 (SAS Institute Inc., North Carolina, USA). Among the 390 samples, the average ADAMTS-13 activity level was 42.8%±31.1. Severe deficiency (ADAMTS-13 activity <10%, 1.7%±1.9, indicative of TTP) was found in 91 samples (23.3%) and borderline ADAMTS-13 activity (15.4%±3.0) in 17 (4.4%) samples. The median age among subjects with TTP was 39 years. The average turnaround time for results was 4.4±5.9 days, with a median of 2.0 days. The average turnaround time was significantly longer for samples from the Arabian Gulf (6.5±6.9 days) compared to those from Colombia (1.2±0.8 days, Wilcoxon/Mann-Whitney W-value=18507.5, P<0.001). In conclusion, the median age of subjects with TTP in this study matched the age reported in the literature. The turnaround time is a global concern, as it can lead to delayed confirmatory results and potentially life-saving treatment. In Colombia, the turnaround time considerably benefits TTP management, underscoring the necessity to determine reasons behind occasional result turnaround delays in the Arabian Gulf.