Statistical Process Control Charts in Healthcare: A Rising Tide of Improvement

In the world of healthcare quality improvement, how we present data can make all the difference. For example, time-series charts are able to highlight changes, but can not show data that is outside expected variation. Recently, there’s been a growing interest in using Statistical Process Control (SPC) charts to help hospitals better understand and improve their performance. But it is not clear how effective the efforts to train healthcare professionals in using these charts are. A new study published in in BMJ Quality & Safety by researchers from our Research Methodology theme sheds light on this question, with some surprising results.

What are SPC charts, and why do they matter?

SPC charts are special graphs that help distinguish between normal variations in data and significant changes that might need attention. Unlike simple before-and-after comparisons, SPC charts give a clearer picture of whether changes in performance are due to real improvements or just random fluctuations.

Testing a training programme

Researchers wanted to see if a training programme called “Making Data Count” could increase the use of SPC charts in English hospitals. Sixteen English NHS hospitals were randomly divided into two groups: staff either received the training (the intervention group), or were put on a waiting list to receive it at a later date (the control group).

The surprise finding: Everyone improved

It was expected that the results would show a significant difference between the hospitals where training was received and those where it wasn’t. But, instead, both groups showed significant increases in their use of SPC charts compared to the start of the study.

In the trained (intervention) group, the use of SPC charts increased by an average of 30 percentage points, while in the untrained (control) group, there was a similar increase of 29 percentage points. This unexpected result suggests that something bigger was happening across the entire healthcare system.

A rising tide of improvement

This phenomenon can be described as a “rising tide” effect (see Chen, et al. 2016). It seems that the push to adopt SPC charts was so strong across the entire NHS that even hospitals not directly involved in the training programme were picking up on the trend.

This spread of knowledge can have happened in various ways:

• Hospitals may have been looking at each other’s publicly available board papers and adopting best practices.
• Word-of-mouth from previously trained professionals might have spread the techniques.
• The broader national initiative to promote SPC charts may have created a culture of change across the entire system.

What does this mean for healthcare improvement?

While the training programme itself didn’t stand out as the sole cause of improvement, the study reveals something perhaps even more important: a system-wide shift towards better data presentation and analysis in healthcare. As SPC charts become a new standard of reporting for NHS hospital trusts, this will reduce the potential for any room for further improvements to be seen in trials.

As an aside, the feedback from those who did receive the training was overwhelmingly positive. Participants reported learning new skills, intending to change their behaviour, and believing the training would positively impact their hospitals’ performance.

This study shows that improving healthcare isn’t always about isolated interventions. Sometimes, it’s about creating a culture of change that spreads across an entire system. As more hospitals adopt SPC charts, the next important step will be to understand how this improved data presentation actually impacts patient care and outcomes.

For those working in healthcare communication and quality improvement, this study is a reminder of the power of system-wide initiatives and the importance of clear, meaningful data presentation in driving positive change.