Evaluation of Prevalence of False Negative Results of CRP Test Using Three Different Kit in Iran

Background: CRP is the main acute phase protein in humans and plays a key role in host defense against infections. This protein is increased in many infections, inflammatory arthritis, autoimmune diseases, neoplastic diseases, pregnancy and elderly

Materials and Methods: this study was done on 400 serum samples that CRP was checked with 3 different kits with slide agglutination method and with photometric method for each sample. Results were compared with quantitative results in photometric method.

Results: statistical results in evaluating 400 serum samples with Anisan, Kimia pajohan and Shim enzyme kits were like below: false negative results were detected in 21, 20 and 33 samples respectively. Sensitivities were 87.6%, 86.2% and 80.5% respectively. Specificities were 84%, 74.1% and 80% respectively. Positive predictive values were 80%, 65.4% and 74.7% respectively. Negative predictive values were 90.2%, 90.5% and 84.9% respectively.

Conclusion: Although Anisan kits have higher sensitivity, specificity and positive predictive values among these three Iranian kits with slide agglutination method, it is advised to use quantitative methods like ImmunoturbidImetry or photometry because of high frequency of false results in agglutination method.