In mid-November, the State of Michigan began reporting testing turnaround data for all labs conducting tests in the state. The data provided is a 14 day average that is updated weekly. It includes the overall statewide testing turnaround and transportation time with breakdowns by lab type and emergency preparedness region, and by lab name. The lab testing data is based on reporting from individual labs to the Michigan Department of Health and Human Services (MDHHS), which can take longer than availability to patients/providers due to a number of factors. This means the reported turnaround time is not an indication of how quickly an individual receives their test results.
According to the website, the turnaround time is calculated by subtracting the date and time of the test being conducted from the time of reported results. It is reported in days where one tenth of a day is about 2.5 hours. The data also includes transportation time, which is used to identify the time between the test being conducted and the lab specimen arriving at the lab for analysis.
Since the first data reported on November 11, 2020, the state turnaround time has averaged between 2.37 days (January 6, 2021) and 3.36 days (December 9) While the shortest turnaround time occurred on the same day as the lowest number of tests (January 6, 2021), there is not a clear connection between lower volumes of testing and faster turnaround. The slowest average turnaround time came with the December 9 report, which is around the midpoint in testing volume. Overall, commercial labs complete around two thirds of total testing statewide. Hospitals are responsible for another 30% and public health labs complete roughly 1%.
Since the data began to be reported, testing rates have declined from nearly 900,000 tests every 14 days (right around the Thanksgiving holiday) to just over 500,000. However, for the past four reporting periods, testing capacity has remained fairly consistent, while transportation times and overall turnaround time have decreased. Commercial and hospital labs both contributed to the state’s fastest overall turnaround time reported in the January 20th data (the most recent available at the time of writing). These faster times indicate that there may be improvements happening in testing infrastructure in the private sector (hospitals and commercial labs).
Overall, commercial labs and public health labs generally have slower turnaround times than hospital labs. However, as you can see below from the most recent data on January 20th, commercial labs are processing the largest proportion of tests, which means the longer turnaround time in public health labs has a smaller impact on the state’s overall turnaround data. It does indicate that there might be additional efficiencies in commercial and hospital, especially since public health labs have shorter transportation times than commercial labs. It’s important to remember that patients might obtain their test results before MDHHS receives the results, so this data can’t be used to prioritize getting a diagnostic test at commercial labs. However, it does reflect potential differences in commercial, hospital, and public health labs such as: electronic versus manual data files, reporting specifications (standard versus non-standard templates), and MDHHS capacity processing dataset at time of submission.
Statewide transportation time has remained fairly stable as well, with a small decline to around half a day, which accounts for about a quarter of the total turnaround time for testing results being reported to MHDHHS. Transportation time for commercial labs is the longest, averaging close to one full day for most reporting periods, which makes their quick turnaround time something to explore more closely for those who understand lab processes in-depth.
The state is divided into eight Emergency Preparedness Regions and testing data is reported for each preparedness region as well, so we can get a better understanding of geographical differences in testing data. As of January 20th, the Metro Detroit region (Regions 2N and 2S) accounted for 39% of total statewide tests in the previous 14 days. This share remains fairly consistent over time. Overall, lab volume doesn’t seem to change significantly over time in different regions. However, there are differences in who processes labs by region, which has some impact on turnaround and transportation time.
The Metro Detroit regions (2N and 2S) are the only regions where more than 1% of testing is processed in public health labs. These public health labs have significantly slower turnaround times than commercial and hospital labs.
Transportation time in Metro Detroit as of 1/20 are 0.37 and 0.36 days in Region 2N and 2S respectively. The slower transportation times are found in Regions 6 and 8, accounting for the Grand Rapids region and Upper Peninsula. These regions account for about 18% of the overall testing capacity in the state and the higher transportation times probably reflect the more rural nature of the communities in these regions. However, transportation times in Region 7, which is the northern part of the Lower Peninsula, are below the state’s average transportation time. There are potential lessons to be learned from Region 7’s swifter transportation times despite being a mostly rural region.
Lengthy transportation times don’t necessarily mean a region has slower overall turnaround times, as the transportation time can account for anywhere from 16.8% to 28% of the overall turnaround time. Region 6, which has the second longest transportation time has an overall turnaround time below the state average. However, region 8, representing the Upper Peninsula has the slowest turnaround time and the longest transportation time. As discussed this is most likely due to the rural nature of the region. Metro Detroit (Regions 2N and 2S) performs slightly slower than most other regions, except for Regions 7 and 8. Further investigation by public health professionals, testing labs, and other experts in this field might be able to optimize processing times in the regions with slower overall test reporting, especially in regions where the transportation is quick but overall reporting lags or where transportation contributes to a large portion of the overall turnaround time.
Regions with faster overall turnaround times seem to have a higher percentage of tests being conducted by hospital labs as of January 20th. For example, Region 1 has the fastest turnaround time and almost half of its tests were performed by hospitals, compared to the state average of 32%. In the slowest regions, Regions 7 and 8, hospital labs conducted a more similar proportion of tests to the state average.
Overall, the testing turnaround data show that the state’s testing capacity remains stable and the processes seem to be improving since turnaround times are declining. While this doesn’t reflect the clinical experience of patients, since patients can receive results before they’re processed by MDHHS, the data is encouraging as we enter into the second year of dealing with the pandemic. It also indicates the state might have the capacity to meet increased demand as new, more contagious strains of coronavirus begin to emerge. Furthermore, the laboratories with faster turnaround times could be used as case studies for others to review and review policies that could contribute to even faster testing results being reported to MDHHS, which would improve pandemic response coordination.