To reduce UTIs, one lab takes a long, wide look

Karen Titus

June 2013—Lance Peterson, MD, wasn’t expecting to be surprised. But the numbers were dramatic enough to startle even him.

Dr. Peterson, an epidemiologist and director of microbiology and infectious diseases research at NorthShore University HealthSystem, in Chicago’s northern suburbs, was looking at figures from the interim analysis of a study he and his colleagues were doing to review presumed urinary tract infections at the four-hospital system. Were they truly UTIs? Or was the laboratory reporting urine culture results in a way that led physicians to treat UTIs that weren’t clinically significant, adding to inappropriate use of antibiotics?

Laboratories in general had been constructing their own Maginot Line of sorts over the years, using culture counts of more than 1,000 or 10,000 colony-forming units per milliliter in reporting diagnostic culture of a urine specimen. That didn’t sit right with Dr. Peterson. Like the famed line in France, the lower thresholds may have seemed like a good idea at one time, but were kaput as a one-size-fits-all reporting strategy.

Several years ago, Dr. Peterson says he spoke with Calvin Kunin, MD, whom Dr. Peterson calls the “grandfather” of urine cultures. He told Dr. Kunin of his suspicions that his lab was overreporting UTIs by using the 1,000 and 10,000 CFU/mL thresholds for inpatients. Dr. Kunin, he says, concurred, saying the thresholds should never drop that low for hospitalized patients. “That gave me a very, very senior person to confirm what I thought we might find” when NorthShore undertook its study, Dr. Peterson says.

Even with that imprimatur, however, Dr. Peterson was impressed by the dramatic change when the threshold shifted to 100,000 CFU/mL. The rate of appropriate detection went up some 73-fold.

When he spoke to his statistician on the project about the interim results, he asked how much longer to continue the study. At this point, the researchers had looked at about 170 cases. “He told us, ‘There’s no point in going any further. It’s just spending more time, and you aren’t going to be able to make the statistics any better,’ ” recalls Dr. Peterson. The study, which eventually looked at 185 cases total, was published last year (Kwon JH, et al. Am J Clin Pathol. 2012;137:778–784).

There was, for Dr. Peterson, one more surprise. Despite the dramatic results, it took a significant amount of time to address the problem once it had been confirmed. Dr. Peterson sounds like a homeowner embarking on a minor—supposedly—renovation project. “It’s not unheard of for me to think we can get it done quicker,” he says. Looking through past messages and interventions, however, Dr. Peterson says he was reminded that he and his colleagues had begun their efforts to lower UTIs 10 years earlier. “I underestimate the time things will take.”

On March 19, NorthShore changed how urine cultures are ordered and results interpreted. Again, the results have been dramatic. Neither legerdemain nor a balancing of the metaphorical ledgers have been involved, though among the steps the lab took, one can be seen, partially, as a type of accounting change. “What we’re doing, in a sense, is changing the threshold so we have fewer false-positives,” Dr. Peterson says.

Data from the first month were remarkable. In the five intensive care units at the four hospitals, there was only one urinary tract infection. “Absolutely amazing,” says Dr. Peterson. “Normally it would be in the eight to 10 range.”

In that period, says Dr. Peterson, there were about 8,000 urine cultures total, of which some 1,700 were inpatient specimens. Of those, a little more than 300 were inpatients who were hospitalized more than two days; 80 of them were affected by the new reporting. When the charts of those patients were reviewed, none of them had a UTI by clinical symptoms. “They did not get antibiotics, and they did fine,” Dr. Peterson says.

While these results are not statistically significant, the new approach should help the hospitals meet the system’s goal of reducing nosocomial UTIs, an infection that, not coincidentally, is now both publicly reportable in Illinois and nonreimbursed by the CMS.

The specter of unwanted publicity, coupled with financial strictures, brought a renewed burst of energy to longstanding laboratory efforts to rein in nosocomial UTIs. In fact, that helped launch the aforementioned study, says Tom Thomson, PhD, director of the microbiology laboratory and division head of clinical pathology. The lab wanted to know how many there were, and what types of patients they occurred in. The conclusion from this project was clear: Half of the so-called nosocomial UTIs that the system would soon be penalized for were not nosocomial UTIs. They weren’t infections at all. Instead, says Dr. Thomson, they were contaminated urines or samples from patients who had asymptomatic bacteriuria. These cases were not associated with symptoms, “and in almost every case would not be treated.”

Getting hospital leaders to make the project a priority was fairly easy. No one wanted the nosocomial UTI rate to be reported as double the actual rate. “The administration said, ‘This is not going to happen,’ ” Dr. Thomson recalls.

After getting administrative support, the lab met with other key players, pitching the proposal and asking for feedback. “And then running for cover,” Dr. Thomson says with a laugh. “It takes time, persistence, and a lot of friends calling in favors.”

The laboratory had its own problems to tackle, including the logistics of figuring out when organisms in urine should be identified and reported. It redid its urine test codes to differentiate the types of urine samples and patients. When physicians place an order for a urine test, they now choose from several types of culture, including:

• culture, bacterial, urine—inpatient (non-straight cath)
• culture, bacterial, urine—outpatient or Emergency Department (non-straight cath)
• culture, bacterial, urine—straight cath or bladder aspirate.

Urologists have their own urine culture test code as well, which enables them to order the testing needed for cystoscopy and other invasive procedures.

Dr. Thomson sums up the laboratory changes in two parts. First, the lab is taking information that’s been there all along, but packaging it differently, so to speak, by redoing the urine codes to help the lab more easily apply standard criteria. The second step was to create a new category of patient—inpatient with a possible urinary tract infection—and apply a new count.

In a related step, Dr. Thomson says, the lab also did away with the highly popular—among clinicians, anyway—reflex urine test. When a physician ordered the test, the lab would do a urinalysis. If the result was normal, no culture was performed. If the result was positive, the urine would be reflexed to microbiology for a culture setup.

The lab wasn’t a fan of this. Most labs aren’t, Dr. Thomson says. “But they’re sort of forced into it by their clinical colleagues,” who consider it a cost-effective way to identify UTIs.

“In truth, it’s not,” says Dr. Thomson. “It misses many positives.”

So the lab asked clinicians why they defended the reflex test so ardently. The clinicians replied: We’re screening for urinary tract infections. “So we showed them the literature, which indicated their beloved approach actually missed 15 percent of UTIs,” says Dr. Thomson. The clinicians countered with, We want it to screen patients before they go to surgery, to see if they have asymptomatic bacteriuria. The lab responded with additional evidence, showing the test missed 50 percent of those patients. The screening, furthermore, is no longer required for many surgeries, Dr. Thomson says. “And the downside of treating them is that they’re going to get C. diff disease.”

After plenty of discussion, the plan moved forward. For Dr. Thomson, there’s an obvious lesson to be learned from this thrust and parry. “You can’t take your opinion and make it a new requirement. You’ve got to take your opinion, round off the corners, support it with medical and scientific evidence.”

It can take time, however, for behavior to catch up to new evidence.

“It’s embarrassing,” says Dr. Thomson. “I’ve been doing this a long time. We’ve been trying to get people to wash their hands, and we’ve been trying to get people to screen for Staph aureus—many things.” Not until the CMS imposed its financial and public reporting penalty were the problems solved. “They were fixed in two years. Embarrassing, but that’s what happened.”

The 100,000 CFU/mL has its roots in clinical research done in the 1950s, says Dr. Thomson. “The good news was the 100,000 figure was a really useful term and differentiated people who were infected from those who were not infected, who had disease from those who did not have disease,” he says.

“The bad news is the research was done on one type of patient: those with pyelonephritis,” he continues. Most of the patients sampled now don’t have that disease; rather, they tend to have prostatitis or bladder infection, he says. “We’ve learned over the decades since the 1950s that 100,000 does not pertain to every single patient who has a urinary tract infection.”