Turnaround time on Covid-19 testing
On Friday 26th June I wrote this on LinkedIn: There are just two things to measure to improve operations - throughput time and variability of throughput time.
How does this apply to testing for Covid-19? You’ll agree, no doubt, the answer is obvious: quick throughput or turnaround time (TAT) is crucial to contact tracing; reliability of TAT is crucial to synchronising receipt of the result with treatment of the patient.
Testing is a process. It can be observed and documented. Delay points, bottlenecks and sources of variation and unreliability can be identified. Laboratories and laboratory networks around the world have been doing just that. For a fascinating view of the process see this US article from 31st March.
So, how have we been doing in SA? I couldn’t find any recent articles but here is some of what I found:
9th March: A private laboratory company offers a ‘private testing’ TAT of 48 hours ‘but is dependent on where the sample is coming from.’ At a ‘cash price of R1400.’
25th March, NHLS press release, with no indication of TAT:
‘With all the five sites functional, the NHLS has the capacity to process 5000 samples in 24 hours. This number will increase to 15,000 in 24 hours in April. At the end of April, the NHLS will be able to process approximately 36 000 test in 24 hours.’
- “The current turnaround time for COVID-19 tests in Gauteng is around 7 days for outpatients and 3-4 days for in-patients,” says an Infectious Diseases specialist at Helen Joseph Hospital.
- Over the last week the NHLS plus private sector labs have together done between 10 000 and 15 000 tests a day - a substantial increase from much lower levels two weeks ago. (Note: no TAT stated.)
Where TAT is stated, one might infer it is from the time the swab is taken or the laboratory receives the sample to the time the result is read by the right clinician. Surely what is important is from the time a person is identified as needing to be tested to the result being read by the right clinician? The latter definition would include queuing (where most of the variability will be happening), transporting, batching, communicating, etc.
I’d be interested if anyone could tell me the average TAT in various hospitals or provinces, along with the variability of TAT.
We should not confuse capacity with TAT. The former is a measure of the rate of processing at the bottleneck. The latter is the ‘journey time’ from start to finish. As an example, in the automotive industry, a car comes off the line every minute, giving a capacity of 60 per hour. But each car probably spends 4 days in the process. The point is that capacity does not tell us the throughput time.
Despite the paucity of current reporting, it is clear that public and private laboratories have increased capacity enormously. A quick check on the published figures shows the number of tests on two consecutive days near the end of June as 38 000 and 30 000 (numbers rounded). Sourced on 30th June from https://www.covid19sa.org
I hope those working to improve the process, are focusing on both the full TAT and the reliability of the TAT. How about setting a target condition of TAT 6 hours with range of 4 to 6 hours? And when that is achieved, to set a more challenging target condition, and so on?
I have no doubt that all of us working in process improvement are willing to offer a helping hand to reduce TATs and reliability of TATs in the testing processes across South Africa. And of course we salute those who have contributed to the improvements evident from recent capacity increases.
As I said, there are just two things to measure to improve operations - throughput time and variability of throughput time….