TABLE 4.

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
    No844
    Yes1,200
Acquisition11.130.0009
    Community acquired946
    Hospital acquired1,070
Admitting service5.31<0.0001
    Obstetrics and gynecology704
    General medicine907
    Urology866
    General Hematology/Oncology806
    Cardiology683
    Neurology845
    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
    Neurosurgery1,051
Polymicrobial4.130.0424
    No955
    Yes1,060
Charlson index score2.640.0325
    01,064
    11,036
    2936
    3, 4, 5958
    ≥61,044
  • 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.