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Screening strip validated to test for spontaneous bacterial peritonitis

The PeriScreen strip provides an efficient, affordable way to diagnose spontaneous bacterial peritonitis in patients with cirrhosis, according to research published in The American Journal of Gastroenterology.

“[The current test of] manual microscopic polymorphonuclear leukocyte count in ascitic fluid is a time-consuming procedure which may delay the initiation of spontaneous bacterial peritonitis treatment,” Thierry Thévenot, MD, PhD, of Hôpital Jean Minjoz, in France, told Healio.com/Hepatology. “There is clearly a need for a simple and rapid bedside diagnostic test.”

Thierry Thévenot

The PeriScreen strip (Serim Research Corporation) — initially intended for locating infections in peritoneal dialysate — changes from light yellow to purple when it is submerged in ascitic fluid, with the colors corresponding to “negative”, “trace”, “small” or “large” amounts of ascitic fluid in a patient.

Researchers studied 1,402 ascetic fluid samples from 649 patients — 315 of them outpatients — with cirrhosis. Spontaneous bacterial peritonitis (SBP) was found in 6% (2.1% of outpatients vs. 11.2% of inpatients; P <.001) and in 7.2% of patients with symptoms suggestive of SBP (3% of outpatients vs. 11.3% of inpatients; P <.001).

At the “small” threshold, negative predictive value (NPV) was 98.7%, positive predictive value (PPV) was 25.9%, specificity was 85.9% and sensitivity was 81%. When the “trace” threshold was used, the K value for inter-reader agreement was 0.81 (95% CI, 0.77-0.84). At that same “trace” interval, NPV was 99.1%, PPV was 12%, specificity was 57.1% and sensitivity was 91.7%. NPV and sensitivity were both 100% in outpatients; comparable numbers were 97.9% and 89.5% in inpatients.

When using the “trace” threshold,  researchers reported 565 false positive results. In a multivariable analysis, they attributed these to:

• bilirubin level (OR = 5.67, 95%CI, 2.67-12.03);
• creatinine level (OR = 2.92, 95%CI, 1.53-5.58);
• leukocyte count (OR = 2.07, 95%CI, 1.07-4.02); and
• presence of systemic inflammatory response syndrome (OR = 3.18, 95%CI, 1.62-6.26).

A different model that included MELD score — but not creatinine and bilirubin — generated false positive results. According to researchers, these were due to:

• MELD score (OR = 4.03, 95%CI, 1.90-8.55); and
• presence of systemic inflammatory response syndrome (OR = 3.73, 95%CI, 2.01-3.73).

Researchers witnessed similar impact of these factors for false positives using the “small” threshold. They also reported several false negative reports within the inpatients (n = 7).

“Considering these impressive results, clinicians can confidently use this strip for their cirrhotic outpatients with ascites to exclude SBP,” Thévenot told Healio.com/Hepatology. “Using the PeriScreen strip as the first-line option in outpatients could also generate substantial cost savings. … And for outpatients the rapid diagnosis of SBP, could allow them to be discharged in a timely manner with no risk of undiagnosed SBP.” – by Janel Miller

Disclosure: The researchers report no relevant financial disclosures.