What is it about?
This expository case study demonstrates the critical utility of Statistical Process Control (SPC) charts—specifically the conventional and Laney modified U-charts—as quality control tools for monitoring the yearly rate of Surgical Site Infections (SSI). The analysis utilized World Health Organization (WHO) data for three countries in the European region: Armenia (ARM), Bulgaria (BGR), and Germany (DEU). The methodology employed the Laney chart after a diagnostic check on the data dispersion to proactively prevent an elevated false alarm rate. The trending charts revealed that Bulgaria initially had the highest SSI percentage but showed a gradual decline interrupted by a single freakish rise, Armenia maintained a relatively lower rate with a steeper decline, and Germany demonstrated the most stable but lowest trend, though its rate slightly tended to increase over time. Throughout the charts, red dots were used to flag years with unusual SSI rates, where points above the control limit signal high-risk periods, and points below the limit indicate opportunities for improvement.
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Why is it important?
The study's importance lies in advocating for the implementation of Statistical Process Control (SPC) in the health-care industry, particularly for monitoring SSI, which is an important quality attribute essential for compliance with good operation practices and patient safety. Shewhart charts are deemed an indispensable tool because they provide a measurable way to assess the current SSI state, deliver early warnings of any process deviations, and allow for the quantitative evaluation of changes and improvements in surgical operations. Crucially, the case study validates the necessity of using the Laney-modified attribute chart when data dispersion (like over-dispersion) is detected, as it prevents the elevated false alarm rates that standard charts would produce, thus ensuring the reliability of the control limits and fostering confidence in the surveillance program. Ultimately, the systematic use of this SPC methodology enables medical staff to spot, investigate, and contain any SSI excursions in a timely manner, safeguarding patient health.
Perspectives
The article adopts a strong quality control perspective, asserting that regular trending and monitoring of SSI must be a mandatory process overseen by personnel well-trained in statistics and control charts. From a practical viewpoint, the use of statistical software programs facilitates the process, offering online visualization of the current SSI states and enabling the establishment of corrections before true out-of-control events fully emerge. Methodologically, the comparison between the three European countries highlights a key perspective: even processes with low rates (like Germany's) that are statistically "stable" may show an undesirable slight upward trend, indicating the need for continuous vigilance and process mean re-stabilization. Conversely, the unstable process variation seen in Bulgaria and Armenia, marked by sudden spikes, underscores the need for further investigation to allocate assignable causes of variability and isolate them from common process fluctuations, ensuring that any achieved lower SSI rates are maintained through a fully controlled system.
Independent Researcher & Consultant Mostafa Essam Eissa
Read the Original
This page is a summary of: Use of Control Charts as a Quality Control Tool for Monitoring of Microbiological Infection Risk during Surgery: An Expository Case, Clinical Journal of Surgery, January 2019, Asclepius Open LLC,
DOI: 10.33309/2639-9164.020102.
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