21 Sep 07
Can procalcitonin guide therapy in newly admitted critically ill patients?
By JAH van Oers, JE Tulleken, JJM Ligtenberg, JHJM Meertens, JG Zijlstra
Neth J Crit Care 2007;11:81-86
Can plasma procalcitonin differentiate sepsis from systemic inflammatory response? Is plasma procalcitonin level a measure of severity of illness and can it be a prognostic factor in sepsis patients in an intensive care unit (ICU)?
Search strategy
Review of medical literature. Prospective studies published in the MEDLINE database that evaluated plasma procalcitonin as marker of sepsis in the intensive care unit were included. Positive and negative likelihood ratios were constructed for each study if possible.
Summary of findings
From the search of the MEDLINE database 11 prospective studies that evaluated plasma procalcitonin as a diagnostic marker in sepsis and systemic inflammatory response patients in the ICU were included. A further four articles were found by searching the bibliographies. Sepsis and systemic inflammatory response populations differed between studies. The total number sepsis patients was 688 and total number of systemic inflammatory response patients 507. PCT values were reported as mean +/- sd in sepsis and systemic inflammatory response patients in five studies, and as median with interquartile range in sepsis and SIRS in 10 studies. Cut-off points were established by using area under the curve in receiver operating characteristics curves. Median cut-off point 1.1 ng/ml; interquartile range 1.0-2.42. area under the curve in the receiver operating characteristics was between 0.66 and 0.97. Sensitivity was between 63% and 100% and for specificity 54% to 94%. Positive likelihood ratios (LR+) and negative likelihood ratios (LR-) could be calculated in 11 studies. The median LR+ was 3.31, interquartile range 2.17-6 and the median LR- was 0.11, interquartile range 0.06-0.16. Pre-test probability ranged from 32% to 83% and was modified by positive negative likelihood ratios to a range of 55%-96% and by negative likelihood ratios – to a range of 0-68%. Severity indexes (SOFA score, SAPS II score and APACHE II score) were used in 11 of the 14 studies. Correlation between plasma procalcitoninlevel and severity index was sporadically reported. In four studies plasma procalcitonin levels in survivors and non-survivors of the sepsis group were measured. Only in the surgical patients of one study there was no significant difference.
Conclusion
Although area under the curve , sensitivity and specificity are fairly good for a diagnostic test to differentiate sepsis from systemic inflammatory response , there is serious doubt whether this influences the decision to treat. The pre-test probability is too high to withhold antibiotics and perform diagnostics procedures. Positive test results will not lead to more prescription and negative test results will not lead to stopping of antibiotics. There are not enough data to draw conclusions about the power of plasma procalcitonin as a measure of severity or prognostic factor.