, based on data from more than 97,000 screening mammograms.
Psychology literature has shown the impact of fatigue on performance in a range of settings, and previous studies have shown that radiologists’ performances are more accurate earlier in their shifts compared to later-shift performance, write Michael H. Bernstein, PhD, and colleagues at Brown University, Providence, R.I., in a study published online Jan. 11 in Radiology.
The effect of time of day on performance may be greater for more detailed imaging modalities that are more “cognitively taxing,” and the effect may be greater in less-experienced radiologists, but the impact of time and experience on overall patient recall and false-positive rates has not been well-studied, the researchers said.
In the retrospective review, the researchers identified 97,671 screening mammograms read by 18 radiologists at one of 12 community sites between Jan. 2018 and Dec. 2019. The researchers analyzed the results by type of image, either standard digital mammography (DM) or the more complex digital breast tomosynthesis (DBT). The researchers separated radiologists into two groups: those with at least 5 post-training years of experience and those with less than 5 post-training years of experience. A total of nine radiologists fell into each category.
Overall, the recall rates were significantly different and higher for DM versus DBT (10.2% vs. 9.0%; P = .006). The false-positive (FP) rate also differed significantly and was higher for DM versus DBT (9.8% vs. 8.6%; P = .004).
The odds of recall increased by 11.5% with each hour of reading time for radiologists with less than 5 post-training years of experience for both DBT (odds ratio, 1.12) and DM (OR, 1.09). For the more experienced radiologists, the odds of recall increased by 1.6% for each hour of reading time for DBT but decreased by 0.1% for DM, with no significant difference.
Similarly, the odds of an FP result increased by 12.1% for DBT and 9% for DM per hour of reading time for radiologists with less experience. For more experienced radiologists, the odds of an FP increased by 1.6% for DBT but decreased by 1.1% for DM per hour of reading time.
Cancer detection (defined as true-positive, or TP) was not higher for DM across time, the researchers note. However, “DBT achieved a higher TP rate than DM regardless of the time of day; this shows that for DBT to maintain a constant and superior TP rate relative to DM, radiologists’ FP rates had to go up as the day went on,” they write. “That is, although DBT achieves a superior TP rate, more junior radiologists appeared to compensate for their fatigue later in the day when using DBT by recalling a broader range of mammograms, more of which were FP findings.”
The researchers caution that their findings were limited by several factors, including the study’s retrospective design and the lack of randomization of the imaging technology, patients, and time of day, which prohibit conclusions regarding causality. Other limitations included the consideration of time of day without the ability to use hours since the start of a clinical shift and the use of a 5-year mark to indicate experience without accounting for work volume.
However, the stronger impact of a time-of-day effect for more junior radiologists agrees with findings from other studies, the researchers add. More empirical research is needed, and the researchers propose a longitudinal study of how time of day affects radiologists as they gain experience, as well as experimental studies to test strategies for mitigating the time-of-day effect observed in the current study.