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Enhancing feedback on performance measures: the difference in outlier detection using a binary versus continuous

Laurien Kuhrij1, Erik van Zwet2, Renske van den Berg-Vos1,3

  • 1Department of Neurology, Amsterdam University Medical Centres, Amsterdam, The Netherlands.

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Summary

Funnel plots comparing continuous vs. binary outcomes identify different outlier hospitals. Continuous data provides a more comprehensive view for performance feedback and targeted improvement initiatives in healthcare.

Keywords:
audit and feedbackperformance measuresquality improvement

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Area of Science:

  • Health Services Research
  • Medical Informatics
  • Quality Improvement

Background:

  • Hospitals use funnel plots for performance feedback, often dichotomizing continuous variables.
  • Binary outcomes in funnel plots lose information and are less sensitive to distributional changes.
  • This limits the ability to identify all underperforming hospitals.

Purpose of the Study:

  • To investigate if continuous and binary funnel plots identify different outlier hospitals.
  • To determine the impact of outcome type on hospital performance feedback.
  • To inform targeted improvement initiatives for hospitals with suboptimal performance.

Main Methods:

  • Examined door-to-needle time (DNT) for 6080 acute ischemic stroke patients across 65 hospitals.
  • Compared outlier hospitals using median DNT versus proportion of patients with substantially delayed DNT (above 90th percentile).
  • Conducted sensitivity analyses using proportion above median and a continuous P90 funnel plot.

Main Results:

  • Median DNT was 24 min; 90th percentile (P90) was 50 min.
  • Binary funnel plot (proportion above P90) showed 58 hospitals with average performance.
  • Continuous funnel plot (median DNT) identified 14 of these hospitals with significantly higher median DNT (24%).

Conclusions:

  • Continuous and binary funnel plots identify different outlier hospitals.
  • Continuous outcomes provide richer data for hospital feedback.
  • This can enhance targeted improvement initiatives for better patient care.