How turnaround time can become an issue in laboratory diagnostic testing 

If you’ve ever had a blood test or a biopsy and questioned the time it takes to receive the results, the answer could be because the process involved can be more complex than you’d imagine, especially when a sample requires testing not once, but up to four times. Even though the range of diagnostic tests now available has increased significantly, and the analytical processes have seen immense technical breakthroughs in the new era of precision or personalized medicine, this is no guarantee of a speedy result.

The complete testing process from start to finish, from when a patient gets a diagnostic test until they get the results back, is called ‘turnaround time’ (TAT). This can be measured in two ways. Laboratory TAT is measured from the time the sample arrives at the molecular pathology laboratory until the result is reported, while total TAT is measured from the time the sample is taken from the patient until the result is reported. The length of both types of TAT can vary not only according to the complexity of the test but the logistics involved. These are some of the reasons why:

  • TAT can vary by methodology
    Different tests can be examined using different platforms and methodologies. A testing platform like Idylla, for example, which is a PCR-based molecular diagnostics system, can analyse and report on a sample in under three hours. It can be used when speed is a priority for physicians, but Next Generation Sequencing (NGS) might have to be used if multiple genes need to be analysed, and that takes longer.
  • NGS will have a much longer TAT
    NGS is perhaps the most complex testing methodology and takes longer to perform. It is not available in all labs and is more likely to be undertaken in academic institutions or commercial laboratories. Diaceutics’ research found that in the US, KRAS testing in NSCLC using NGS has an average laboratory turnaround time of 13 days compared with Sanger sequencing with an average of nine days.
  • TAT can vary by region
    Laboratories located in a certain region may have longer average TAT if NGS is their primary methodology but it can also be influenced by infrastructure issues and the logistics of transporting samples in some areas.
  • TAT can vary with the use of sample batching
    Some labs operate sample batching – the process of waiting for a number of samples to arrive at the lab so that they can be tested together rather than individually. The lab will try to collect samples over the course of seven to ten days and then run a single test batch for all samples. For the laboratory it is a question of trying to balance efficiencies by running tests together with minimizing the time it takes to report the result.

Precision medicine is such a fast-moving space that new platforms and even digital imaging of pathology samples are likely to speed the interpretation and reporting aspects of TAT but there will always be fundamental issues to address. These include the logistics involved in getting a sample to and from the lab, tight budgets for new equipment and the cost to train staff to run novel tests and use new technology. We appreciate the vital role laboratories play in ensuring patients are tested at an early stage but also understand the importance of identifying where the lab process can be improved to prevent patients from missing out on the targeted therapies they urgently need.

On December 5, 2017, Diaceutics is hosting a webinar discussing Why 50% of patients could be missing out on the right targeted therapy, which will go into more details about maximizing the number of patients being tested. To register for the webinar please click here.

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