Dear colleagues

I need some help in interpreting some STATA output which is quoting AIC/BIC.  Effectively, I am using MIDAS to pool some sensitivity and specificity values for different cutoffs on a diagnostic test.  Alas sensitivity and specificity may vary not only dependent on the cutoff but also due to variation in the background vaccination rate for a related condition.

I have generated the following output from midas, which quotes BIC and AIC for the contribution of the variable 'vaccrate'.  Could anyone help me interpret whether this could be considered as a significant contribution or not?




 
 
Estimating Covariate Effect Of:  vaccrate
 


Sensitivity and Specificity



Joint Model



SUMMARY DATA AND PERFORMANCE ESTIMATES

 
Number of studies =  18
 
Reference-positive Units = 6185
 
Reference-negative Units =  625
 
Pretest Prob of Disease = 0.91
 

Deviance = 263.5
 
AIC = 273.5
 
BIC = 281.4


BICdiff = 657.1
 
 
Correlation (Mixed Model)= -0.90
 
Proportion of heterogeneity likely due to threshold effect = 0.80


Interstudy variation in Sensitivity: ICC_SEN =  0.17, 95% CI = [ 0.05- 0.29]



Interstudy variation in Sensitivity: MED_SEN =  0.68, 95% CI = [ 0.62- 0.77]

 
Interstudy variation in Specificity: ICC_SPE =  0.20, 95% CI = [ 0.09- 0.31]

 
 
Interstudy variation in Specificity: MED_SPE =  0.70, 95% CI = [ 0.65- 0.77]

 
 
ROC Area, AUROC = 0.84 [0.80 - 0.87]


Heterogeneity (Chi-square): LRT_Q = 246.886, df =2.00, LRT_p =0.000

Inconsistency (I-square): LRT_I2 =  99, 95% CI = [ 99-100]



Parameter                   Estimate          95% CI

Sensitivity                     0.69 [    0.59,    0.78]

Specificity                     0.84 [    0.77,    0.89]

Positive Likelihood Ratio        4.3 [     3.3,     5.7]

Negative Likelihood Ratio       0.37 [    0.29,    0.47]

Diagnostic Odds Ratio             12 [       9,      16]


Thanks to all

Neville
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