Implementing Novel Predictive Parameters in Apheresis

Background:

Reducing the time a patient is present in the apheresis facility for autologous collection can help transplant centers better utilize staff.  Waiting for CD34+ cell count results can delay start of apheresis for an hour or more.  An alternative test for prediction of stem cell mobilization using HPC count to provide a quickly resulted (<5 minutes) proxy for CD34+ results was explored.  The HPC parameter is measured using the Sysmex XE analyzer and is a less mature cell with a 0.7 correlation with CD34+ cell count. We implemented this test in combination with CD34+ testing to identify patients who could start apheresis without waiting for the CD34+ results.  The goal was to reduce patient wait time and deliver the product to the processing lab earlier, with better utilization of technicians.

Methods:

Using previously collected data, our center decided to collect immediately any autologous patient not mobilized with AMD who had an HPC value of over 30.  The cutoff was set high to minimize false positives, patients who were run who ultimately had low counts.  Based on the guideline we established, we allocated patients to two subsets: move to apheresis without waiting for CD34+ results or hold for CD34+ results. Patients who were held pending CD34+ results were subsequently assessed according to Institute standards.  We collected baseline and post-implementation data to assess how much time patients were spending in apheresis and the time that elapsed before delivery to the processing lab pre- and post-implementation.

Results:

Of the eligible patients, 62% could begin apheresis upon HPC resulting and 38% were categorized as needing to wait for CD34+ results.  In the first 3 months post-implementation, patients who initiated collection based on the HPC parameter were found to begin collecting 40 minutes earlier than historic averages, and over an hour earlier than those patients who were held pending the CD34 results.  However, it was observed that the lab receipt time for these patients was equivalent to our baseline. Using the HPC parameter and a cutoff of 30, mobilization was adequately predicted 86.4% of the time. For Table 1 n=66.

Table 1

	HPC > 30	HPC < 30
CD34+ > 10	56.1%	6.1%
CD34+ < 5	7.6%	30.3%

Conclusion:

Based on these findings, it was determined that this approach for evaluating patient readiness for collection provides an opportunity to reduce time from arrival in the donor room to start of collection.  However, further adjustments in communication and scheduling the delivery of the product to the processing laboratory is required to take advantage of the earlier availability of the product.   Upon further investigation, the earlier arrival of products coincided with times that had been historically underutilized and had been repurposed for lab meetings and other tasks.  This approach does provide an opportunity to reduce downtime in the overall process and better control utilization of resources.