Anchoring – Does Information from Triage Bias Our Workup?
September 29, 2023
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Written by Seth Walsh-Blackmore
Spoon Feed
Veterans Affairs (VA) patients with known congestive heart failure (CHF) presenting for shortness of breath as a chief complaint were less likely to receive testing for venous thromboembolism (VTE) when triage reported CHF.
Throw the anchors away!
Maintaining a broad differential, especially for high-risk conditions, is a critical function of EPs. Anchoring bias, when providers prioritize particular (usually initial) information in their differential, is thought to be common, but scant evidence exists.
This was a VA database review of patients with a CHF history presenting for shortness of breath from 2011-2018. It included 108,019 patients, 4,392 with CHF noted in the reason for visit section by triage who were compared to the remainder for VTE testing (a composite endpoint of D-dimer, CT chest with contrast, perfusion scan, or DVT ultrasound) and pulmonary embolism (PE) diagnosis in the ED or within 30 days.
A smaller proportion of patients were tested for VTE: 8.2% vs. 13.4%, difference -5.2% (95%CI -6.2 to -4.2) when CHF was noted by triage. The same was true of VTE diagnosis in the ED despite no significant difference in 30-day diagnosis. Patients with CHF history also received more BNP testing (81.4% vs 71.4%).
However, a greater proportion of those who did not have CHF listed by triage were tachycardic (21.2% vs 13.7%), had recent malignancy (16.0 vs. 12.8%), had recent PE/DVT (12.6 vs 11.1%), and were less likely to have prior admissions for CHF exacerbation (25.5% vs 43.6%). These were statistically significant differences. The composite PE testing outcome includes tests not exclusive to a PE workup. Why CHF was listed in triage for particular patients is unknown and not likely random.
How will this change my practice?
This draws attention to an essential consideration in our teaching and training. The issue is not triage providing the information but how we respond.
Another Spoonful
Are you biased towards VA database studies of bias? The authors also studied the availability heuristic in PE testing. Framing Bias was previously covered on JournalFeed.
Source
Evidence for Anchoring Bias During Physician Decision-Making. JAMA Intern Med. 2023 Aug 1;183(8):818-823. doi: 10.1001/jamainternmed.2023.2366.