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A primer on PDSA: executing plan–do–study–act cycles in practice, not just in name
  1. Jerome A Leis1,2,3,
  2. Kaveh G Shojania1,3
  1. 1Centre for Quality Improvement and Patient Safety, University of Toronto, Toronto, Ontario, Canada
  2. 2Divsion of Infectious Diseases, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
  3. 3Department of Medicine, University of Toronto, Toronto, Ontario, Canada
  1. Correspondence to Dr Jerome A Leis, Sunnybrook Health Sciences Centre, H463, 2075 Bayview Avenue, Toronto, Ontario, Canada M4N 3M5; jerome.leis{at}

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Plan-do–study–act (PDSA) cycles are the building blocks of iterative healthcare improvement.1 Although frequently regarded as separate from research,2 this quality improvement method remains rooted in the scientific method. The P in PDSA usually stands for ‘plan’ but could just as easily refer to ‘predict’. Each cycle combines prediction with a test of change (in effect, hypothesis testing), analysis and a conclusion regarding the best step forward—usually a prediction of what to do for the next PDSA cycle.3

Too often, however, improvement teams go through the motions of PDSA cycles without really embracing its spirit or applying its scientific method. For example, an improvement team might talk about having used PDSA when in reality the original change idea remained roughly unchanged throughout the project, with no refinements to the intervention or the plan to implement it. Quality improvement rarely works out so smoothly. Even among published studies, which presumably include better than average projects, the application of PDSA falls short, with less than half of studies meeting minimum characteristics of PDSA.4 Sometimes PDSA seems more like a quality improvement catch phrase than it does a recognisable scientific process.

In this paper, we review a recent improvement project5 to draw examples of real-world application of PDSA. This project was not chosen to place it on a pedestal in terms of the improvements achieved but rather to demonstrate PDSA methodology and highlight the benefits of putting it into practice.

Illustrative example: project to reduce unnecessary urinary catheters among patients on general medical wards

Urinary catheter overuse contributes to unnecessary patient harms including local trauma, decreased mobility, delirium and infection.6 As in many institutions, the practice at our tertiary care hospital in Toronto had been to leave decisions about insertion and removal of urinary catheters to the discretion of individual physicians without any systematic process to reassess them. Clinicians and infection control …

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  • Competing interests KGS is the Editor-in-Chief of BMJ Quality & Safety.

  • Provenance and peer review Commissioned; internally peer reviewed.

  • i A medical directive is an order given in advance by physicians (or others authorised to write orders) to enable a qualified health professional (typically a nurse) to decide to apply the order under specific conditions without a direct assessment by the physician at the time.8For instance, a medical directive might authorise for triage nurses in the ED to obtain an ECG on a patient with chest pain without waiting for a physician to enter a direct order.

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