Multiple linear regression analysis of independent predictors of microbiology laboratory chargesa

FactorF valueP valueCost ratioLeast squares mean of charges (dollars)b
Total no. of blood cultures drawn
    Linear term329.47<0.00011.21
    Quadratic term90.34<0.00010.99
Length of stay100.62<0.00011.01
Presence of endotracheal tube at T049.70
    Community acquired946
    Hospital acquired1,070
Admitting service5.31<0.0001
    Obstetrics and gynecology704
    General medicine907
    General Hematology/Oncology806
    Other (including psychiatry)927
    Vascular surgery1,299
    Solid organ transplant1,270
    Burn unit1,838
    General surgery961
    Bone marrow transplant1,062
    Cardiovascular surgery1,098
    Orthopedic surgery1,288
Charlson index score2.640.0325
    3, 4, 5958
  • a R = 0.75.

  • b Adjusted for mean values of covariables, i.e., length of stay = 19.7 days and no. of blood cultures drawn = 5.25.