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Entries » Blog » Risk in perspective: A rare heart surgery infection explained with data

Risk in perspective: A rare heart surgery infection explained with data

Created Jan 08 2018, 11:59 AM
  • Heart Disease
  • Health care data
  • Bacterial Infection

Darshak Sanghavi, MD; Samantha Noderer, MA

Rondi remembers the day she got the letter in the mail from her hospital in central Massachusetts. It was addressed to her, but was about her teenaged son, Cole, who was born with a heart defect and underwent cardiac surgery a few months earlier. Like Rondi, thousands of other patients and families across the country were opening similar letters from their doctors in the fall of 2015.


We are notifying patients who have had open-heart surgery, about a potential infection risk related to this surgery. We are contacting you today, as you or a member of your family have been identified in clinical records as a patient who might be affected...


Rondi had many questions.

“It was definitely nerve-racking,” said Rondi. “I was glad to know about the issue but my biggest concern was: How bad is it? Is this letter telling me everything?”

Rondi was just one of thousands of people who received this letter because of a spike in reported infections connected to a device used in heart surgeries. But should Rondi have been concerned? Was there a real imminent threat to her son’s health? 

In this blog post, we will look at how data can provide important context on health risks, assisting us in determining when and how to communicate to patients. 

A rare bacterial infection sourced from a commonly used device

The risk of infection was linked to bacteria that contaminated heater-cooler devices used during open chest surgeries. According to tests, contamination may have occurred during manufacturing of the equipment. More than 250,000 heart bypass procedures are performed each year in the U.S. with the help of these heater-cooler devices that regulate body temperatures. This could have been a major public health crisis.

Graphic representation of heater-cooler circuits tested for transmission of mycobacterium chimaera.

The suspect was a type of bacteria known as nontuberculous mycobacterium (NTM). While most people exposed to these bacteria never get an infection, a spike in reports of infections in patients linked to contaminated heater-cooler devices concerned public health officials at the Centers for Disease Control and Prevention (CDC). They asked providers to inform patients of the infection risk, which resulted in the letter Rondi received.

“The letter explained that the signs of an infection could take several months or years to show. And the list of potential symptoms was very broad, such as night sweats, muscle aches, weight loss, fatigue and unexplained fever,” said Rondi. “I was most nervous to tell Cole about the letter without more information. It wasn’t until we spoke with our cardiologist and he clearly explained the small risk and how it relates to my son specifically, that we felt more at ease.”

Based on a few published studies, the CDC estimated that the risk of a patient getting an infection was between about 1 in 100 and 1 in 1,000. This is a large range, which can be stressful for patients when the risks are not put into proper perspective.

We asked ourselves whether it was possible to find a more precise estimate of risk. Knowing the precise risk could better inform public health communications and keep families like Rondi’s at ease in the event of future outbreaks.

To answer this question, OptumLabs queried our data set of commercial and Medicare Advantage claims for more than 127 million people over 20 years.

Demonstrating real-world risks with real-world data

We explored the risk of mycobacterial infection among a group of patients who had claims for open heart bypass surgery between July 1, 2007 and June 30, 2015 and compared it to the risk of infection among patients who had claims for angioplasty —  a non-open heart cardiac procedure that does not involve a heater-cooler device — during the same time period. Both groups of patients had very similar health conditions. Because the only major difference between them was the type of surgery they had, we were able to isolate the impact of the heater-cooler device used in open heart surgery. Infection was defined by looking at ICD-9 diagnosis codes for treatment with rifabutin, a common antibiotic used to fight the infection.

Looking at patients enrolled in the health plan for four years in a row, the small rate of infection among patients who had bypass surgery with a heater-cooler device was not statistically higher than the rate of infection among patients who had angioplasty without a heater-cooler device. In short, it appears that the actual risks to patients were quite low.

Chart showing difference in risk between those with or without bypass surgery is not significant

This initial analysis isn't definitive by any means, but shows how health care data can help point us in the right direction to guide patients, and support doctors when communicating the risks of one treatment or procedure over another to patients. 

Looking at these results, should a letter have been sent to Rondi? We would argue that the letter should have been written with more precision, informed by data, and ready to answer patients’ second and third questions. Ideally, patient communications should provide relevant information that can help them put complicated risks into perspective. It can reduce confusion and prevent unnecessary worry.

When it comes to our health or the health of a loved one, it’s often the questions left unanswered that can cause more distress than even the worst news. With the help of data, we can work to get the right answers to the right people to guide important real world decisions and positive outcomes.

 

About the authors:  

*Darshak Sanghavi, MD, is chief medical officer at OptumLabs

*Samantha Noderer, MA, is communications & translation manager at OptumLabs