An algorithm of three physician billing codes ( separated by at least @days ) in @years or one hospitalization had a sensitivity of @ % ( @ % confidence interval -LSB- CI -RSB- @-@ @ % ) , specificity of @ % ( @ % CI @-@ @ % ) , positive predictive value ( PPV ) of @ % ( @ % CI@-@ @ % ) , and negative predictive value ( NPV ) of @ % ( @ % CI@-@ @ % ) for identifying patients who had ever had epilepsy .