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Weve done multiple columns on the weekend effect and the after hours effect, in which patient outcomes tend to be worse than for those during normal daytime hours. But beyond time of day or day of the week, there is variation in performance by time during a working shift.
In our May 3, 2011 Patient Safety Tip of the Week Its All in the Timing we noted that detection rates for polyps or adenomas during colonoscopy fell off during colonoscopies done later in a shift. And in our June 2019 What's New in the Patient Safety World column More on the Time of Day we noted your chance of getting an influenza vaccination or one of several preventive screening procedures also falls off when you are seen late in the day.
The phenomenon is seen in radiologists, too. In our August 25, 2020 Patient Safety Tip of the Week we noted a study which looked at the performance of radiology fellows who have completed full radiology residencies (all of whom successfully completed the American Board of Radiology board certification following their fellowship year), comparing CT scan reading error rates during daytime or night shifts (Patel 2020). Nighttime studies had error rates of 3%, compared to 2% for daytime studies, and 69% of the radiology fellows had higher error rates for night cases. But, while the focus of the study was on nighttime vs. daytime error rates, there were significantly more errors during the last half of night assignments (3.7%) compared with the first half (2.5%). Diagnostic error rates were also lower in the first half of the day assignment from 7:00 AM to 11:59 AM compared with the second half from 12:00 PM to 5:59 PM (1.1% vs. 2.6%), but that difference was not statistically significant.
A new study (Bernstein 2022) showed that patients were more likely to be recalled when their screening digital breast tomosynthesis images were interpreted later in the day by less-experienced radiologists. Thr researchers looked at recall and false-positive (FP) rates in radiologists interpretation of digital breast tomosynthesis (DBT) images digital mammography (DM) images (the authors note that digital breast tomosynthesis image interpretation might be more cognitively demanding than interpretation of digital mammography images). But they also looked at the impact of time of day on these rates.
Overall, for every additional hour of reading time, the odds of recall increased by 6.6% for DBT, a sharper increase than that for DM. Similarly, for every additional hour in reading time, the odds of an falso positive finding increased by 6.8%, whereas the increase for DM was 3.9%. For every additional hour in reading time, the odds of a true positive finding increased by 3.4% for DBT and by 2.2% for DM. But results were significantly impacted by experience of the radiologist. For radiologists with 5 or fewer posttraining years of experience, odds of recall increased 11.5% with every hour when using DBT, but this was not found for DM. For radiologists with more than 5 posttraining years of experience, no evidence of increase in recall was observed for DBT or DM.
Physicians, nurses, and really all healthcare workers tend to have drop-offs in performance when fatigued. There are, of course, multiple studies demonstrating the impact of fatigue on on radiologists. Krupinski et al. (Krupinski 2010) found that, after a day of clinical reading, radiologists have reduced ability to focus, increased symptoms of fatigue and oculomotor strain, and reduced ability to detect fractures. In our April 2018 What's New in the Patient Safety World column Radiologists Get Fatigued, Too we highlighted a study looking at the effect of overnight shifts on performance of radiologists (Hanna 2018). The researchers used a tool for measuring fatigue and advance eye tracking technology to assess the performance of radiologists (both attendings and residents). Not surprisingly, participants demonstrated worse diagnostic performance in the fatigued versus not-fatigued state. Viewing time per case was significantly prolonged when the radiologists were fatigued. Mean total fixations generated during the search increased by 60% during fatigued sessions. Mean time to first fixate on bone fractures increased by 34% during fatigued sessions. Moreover, dwell times associated with true- and false-positive decisions increased, whereas those with false negatives decreased. Effects of fatigue were more pronounced in residents, in keeping with the findings of Bernstein et al. regarding the impact of experience.
Hanna et al. concluded that further research is needed to address and reverse the impact of such fatigue-related changes. They speculate that environmental changes (eg. lighting) and activity changes (eg. periodic breaks, moving around, etc.) might help mitigate the adverse effects of fatigue on performance.
Some of our other columns on the impact of time of day on patient outcomes:
May 3, 2011 Its All in the Timing
June 2019 More on the Time of Day
August 25, 2020
Some of our other columns on the role of fatigue in Patient Safety:
November 9, 2010 12-Hour Nursing Shifts and Patient Safety
April 26, 2011 Sleeping Air Traffic Controllers: What About Healthcare?
February 2011 Update on 12-hour Nursing Shifts
September 2011 Shiftwork and Patient Safety
November 2011 Restricted Housestaff Work Hours and Patient Handoffs
January 3, 2012 Unintended Consequences of Restricted Housestaff Hours
June 2012 June 2012 Surgeon Fatigue
November 2012 The Mid-Day Nap
November 13, 2012 The 12-Hour Nursing Shift: More Downsides
July 29, 2014 The 12-Hour Nursing Shift: Debate Continues
October 2014 Another Rap on the 12-Hour Nursing Shift
December 2, 2014 ANA Position Statement on Nurse Fatigue
August 2015 Surgical Resident Duty Reform and Postoperative Outcomes
September 2015 Surgery Previous Night Does Not Impact Attending Surgeon Next Day
September 29, 2015 More on the 12-Hour Nursing Shift
September 6, 2016 Napping Debate Rekindled
April 18, 2017 Alarm Response and Nurse Shift Duration
July 11, 2017 The 12-Hour Shift Takes More Hits
February 13, 2018 Interruptions in the ED
April 2018 Radiologists Get Fatigued, Too
August 2018 Burnout and Medical Errors
September 4, 2018 The 12-Hour Nursing Shift: Another Nail in the Coffin
August 2020 New Twist on Resident Work Hours and Patient Safety
August 25, 2020 The Off-Hours Effect in Radiology
September 2020 Daylight Savings Time Impacts Patient Safety?
January 19, 2021 Technology to Identify Fatigue?
October 12, 2021 FDA Approval of Concussion Tool Why Not a Fatigue Detection Tool?
Patel AG, Pizzitola VJ, Johnson CD, et al. Radiologists Make More Errors Interpreting Off-Hours Body CT Studies during Overnight Assignments as Compared with Daytime Assignments. Radiology 2020; 297(2): 374-379 Published Online: Aug 18 2020
Bernstein MH, Baird GL, Lourenco AP. Digital Breast Tomosynthesis and Digital Mammography Recall and False-Positive Rates by Time of Day and Reader Experience
Radiology 2022; Publlished online January 11, 2022
Krupinski EA, Berbaum KS, Caldwell RT, Schartz KM, Kim J. Long radiology workdays reduce detection and accommodation accuracy. JAm Coll Radiol 2010; 7(9): 698-704
Hanna TN, Zygmont ME, Peterson R, et al. The effects of fatigue from overnight
shifts on radiology search patterns and diagnostic performance. J Am Coll Radiol 2018; 15(12): 1709-1716
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