The Agreement between Feline Pancreatic Lipase Immunoreactivity and DGGR-Lipase Assay in Cats—Preliminary Results

Abstract

The colorimetric catalytic assay based on the use of 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6′-methylresorufin) (DGGR) ester as a substrate for pancreatic lipase activity is commonly used for the diagnosis of pancreatitis in dogs and cats. Even though the assay has generally been shown to yield consistent results with feline pancreatic lipase immunoreactivity (fPLI) assay, the agreement may vary between assays of different manufacturers. In this study, the chance-corrected agreement between a DGGR-lipase assay offered by one of the biggest providers of diagnostic solutions in Poland and fPLI assay was investigated. The study was carried out on 50 cats in which DGGR-lipase activity and fPLI were tested in the same blood sample. The chance-corrected agreement was determined using Gwet’s AC1 coefficient separately for the fPLI assay’s cut-off values of >3.5 μg/L and >5.3 μg/L. The DGGR-lipase activity significantly positively correlated with fPLI (Rs = 0.665; CI 95%: 0.451, 0.807, p < 0.001). The chance-corrected agreement between the fPLI assay and DGGR-lipase assay differed considerably depending on the cut-off values of the DGGR-lipase assay. When the cut-off value reported in the literature (>26 U/L) was used, it was poor to fair. It was moderate at the cut-off value recommended by the laboratory (>45 U/L), and good at the cut-off value recommended by the assay’s manufacturer (>60 U/L). The highest agreement was obtained between the fPLI assay at the cut-off value of 3.5 μg/L and the DGGR-lipase assay at the cut-off value of 55 U/L (AC1 = 0.725; CI 95%: 0.537, 0.914) and between the fPLI assay at the cut-off value of 5.3 μg/L and the DGGR-lipase assay at the cut-off value of 70 U/L (AC1 = 0.749; CI 95%: 0.577, 0.921). The study confirms that the chance-corrected agreement between the two assays is good. Prospective studies comparing both assays to a diagnostic gold standard are needed to determine which of them is more accurate.

Effects of prednisolone on 1,2‐O‐dilauryl‐rac‐glycero glutaric acid‐(60‐methylresorufin) ester‐lipase activity and pancreatic lipase immunoreactivity in healthy cats

“…[DGGR]-based lipase assays) 3 has thus largely replaced histopathology as a surrogate gold standard for the diagnosis of pancreatitis in cats. [4][5][6][7][8][9] Both tests correlate strongly. 6,8 When compared with a standardized pancreatic histopathologic examination of the entire pancreas, 2 or to a detailed pancreatic ultrasonographic examination, 8 the LIPC Roche lipase assay and the PLI assay have comparable diagnostic sensitivity and specificity.…”

“…Because clinical signs are often vague and nonspecific in cats with pancreatitis, and it can be difficult to ensure a complete ultrasonographic visualization of the entire pancreas, extra emphasis has been placed on lipase measurements in the last 15 years. Determination of serum lipase, either as a concentration (pancreatic lipase immunoreactivity [PLI]) or an activity (1,2‐o‐dilauryl‐rac‐glycero‐3‐glutaric acid‐(60‐methylresorufin) ester [DGGR]‐based lipase assays) 3 has thus largely replaced histopathology as a surrogate gold standard for the diagnosis of pancreatitis in cats 4‐9 . Both tests correlate strongly 6,8 .…”

Analytical validation of an ELISA for the measurement of feline pancreas‐specific lipase and re‐evaluation of the reference interval and decision threshold for diagnosing pancreatitis

“…Serum lipase activity, as measured by assays using 1,2-o-dilauryl-rac-gly cero-3-glutaric acid-(6′-methylresorufin) ester (DGGR) as a substrate, has been evaluated for its diagnostic utility in pancreatitis in cats and was shown to have a good agreement with the Spec fPL assay. 9,10,15 However, studies focused on agreement need to be interpreted cautiously for several reasons: (1) DGGR is not a specific substrate for hydrolysis by pancreatic lipase but is also broken down by other enzymes 16 and as a result, lipase of extra-pancreatic sources could impact the results of the DGGR lipase activity assay;…”

“…The variation of the sensitivity and specificity might partly be due to differences in study design. Serum lipase activity, as measured by assays using 1,2‐o‐dilauryl‐rac‐glycero‐3‐glutaric acid‐(6′‐methylresorufin) ester (DGGR) as a substrate, has been evaluated for its diagnostic utility in pancreatitis in cats and was shown to have a good agreement with the Spec fPL assay 9,10,15 . However, studies focused on agreement need to be interpreted cautiously for several reasons: (1) DGGR is not a specific substrate for hydrolysis by pancreatic lipase but is also broken down by other enzymes 16 and as a result, lipase of extra‐pancreatic sources could impact the results of the DGGR lipase activity assay; (2) agreement between different biomarkers is not equivalent to these biomarkers having the same sensitivity and specificity 17 and thus differentiation between health and disease; (3) agreement of a biomarker with a reference standard (eg, ultrasound results or histopathology) might be influenced by the imperfection of the selected reference standard (for example, the result of the reference standard might be affected by differences in disease severity, disease chronicity, and lesion distribution), as early pancreatitis might not be associated with evident morphologic changes 18 .…”