Abstract
BACKGROUND: Patient-facing displays of laboratory test results typically provide patients with one reference point (the "standard range"). OBJECTIVE: To test the effect of including an additional harm anchor reference point in visual displays of laboratory test results, which indicates how far outside of the standard range values would need to be in order to suggest substantial patient risk. METHODS: Using a demographically diverse, online sample, we compared the reactions of 1618 adults in the United States who viewed visual line displays that included both standard range and harm anchor reference points ("Many doctors are not concerned until here") to displays that included either (1) only a standard range, (2) standard range plus evaluative categories (eg, "borderline high"), or (3) a color gradient showing degree of deviation from the standard range. RESULTS: Providing the harm anchor reference point significantly reduced perceived urgency of close-to-normal alanine aminotransferase and creatinine results (P values <.001) but not generally for platelet count results. Notably, display type did not significantly alter perceptions of more extreme results in potentially harmful ranges. Harm anchors also substantially reduced the number of participants who wanted to contact their doctor urgently or go to the hospital about these test results. CONCLUSIONS: Presenting patients with evaluative cues regarding when test results become clinically concerning can reduce the perceived urgency of out-of-range results that do not require immediate clinical action.