Validation of Irma Cgea/crenk One Method of Evaluation of the Vitamin D at the Regional Center of Nuclear Study Laboratory of Kinshasa

Abstract

The aim of the present study was to validate the method IRMA CGEA/CRENK for the evaluation of the vitamin D status by comparison to the commercial method DIASORIN. A blood sample was obtained from 30 volunteers with a good health state in general population (11 women and 19 men) to determine serum 25(OH) D, concentrations by all those methods. Using local laboratory cutoffs, vitamin D insufficiency and deficiency was defined as 25(OH) D values of 4-14 ng/ml and ˂ 4 ng/ml, respectively; vitamin D sufficiency as ≥15ng/ml [23]. Statistical analyses were performed using Excel 12.0 and SPSS 21 statistical software’s. Mean and standard deviation (SD), were used to evaluate the mean of vitamin D of the two methods. Student t TEST was used to compare mean of the two methods.  P value ≤ 0.05 defined the level of statistical significance. PEARSON correlation coefficient (r) was performed to evaluate the correlation between the two methods.  An r=0 means the missing of correlation: r<0 means a negative correlation; r=1 means a positive and perfect correlation; 0, 75<r<1 means a positive and strong correlation.  The concordance between IRMA CGEA/CRENK and the commercial method DIASORIN has been definite as the missing of statistic difference between the means of vitamin D with the two methods and a positive correlation between the levels of vitamin D of the two methods. The coefficient kappa was calculated for avoiding the rate of random in the concordance. The variations of the coefficient Kappa is ±1.  K= -1 means total discordance.  K=+1 means an absolute concordance. K near 0 means a mean concordance explain by random. K>0, 8 (80%) is the limit of the better concordance. No statistic difference was observed between the means of vitamin D of the method IRMA CGEA/CRENK and the commercial method DIASORIN (p=0,330).  The coefficient of correlation was: r = 0, 96. The equation of correlation was: y =1,429 + 1, 02 x (y= IRMA CGEA/CRENK, x= DIASORIN Commercial).  The coefficient kappa = 0, 85.