Each week, we will be publishing layman’s abstracts of new articles from our prestigious portfolio of journals in statistics. The aim is to highlight the latest research to a broader audience in an accessible format.

The article featured today is from Statistics in Medicine, with the full article now published in Volume 40, Issue 5 and available to read here.

Westerberg, M, Larsson, R, Holmberg, L, Stattin, P, Garmo, H. Simulation model of disease incidence driven by diagnostic activity. Statistics in Medicine. 2021; 40: 1172– 1188. https://doi.org/10.1002/sim.8833

A recently published study in the journal Statistics in Medicine examined the relationship between diagnostic activity and the risk of prostate cancer using data from Prostate Cancer data Base Sweden (PCBaSe).

Since the early 1990’s, the diagnostic activity in Sweden has increased, mainly due to increased use of PSA testing in asymptomatic men. The increase has varied greatly over both calendar time, and between age groups and regions. For example, in some regions uptake of PSA testing was very early while in other regions uptake was slower. Previous research on the link between diagnostic activity and prostate cancer has mainly focused on the effects of formal screening by use of PSA testing. In contrast, his study focused on the effects of the opportunistic PSA-testing that has been conducted in Sweden for a long time.

Although comprehensive data on PSA-testing and biopsies are now collected, it was not available for most part of the study period. Therefore, the authors used a new method that does not require such data, but is based on the fact that there have been large differences in incidence between the regions over time and between age groups. This method was used to predict incidence and mortality of prostate cancer until 2060. Under the scenario, there would be (A) stable moderate diagnostic activity or (B) a decrease in diagnostic activity comparable with the early 90’s. The results point to a clear effect on the incidence, where a higher diagnostic activity as in A, compared to B, leads to fewer diagnosis of  metastatic prostate cancer, and fewer deaths, but also to significantly more diagnoses of  lower-risk tumor.

It is exciting that with high-quality national data we can capture and describe the effects of the diagnostic activity on a very long time scale, says Marcus Westerberg, doctoral student at the Department of Mathematics at Uppsala University. The results are in line with previous screening studies, albeit somewhat more moderate, and indicate that it takes up to 30 years, from the time a change is diagnostic activity is introduced until the full effects on mortality can be observed.

The authors plan several works based on their new method that aim to increase understanding of the effects of the diagnostic activity on incidence, treatment patterns, side effects, and mortality.