Table 3

Factors influencing the likelihood of postoperative visual acuity being 0.5 or better

STD errorConfidence interval 95% CI for exp (b)
VariableCoefficient bSE (b)p ValueOdds ratio exp(b)LowerUpper
Final statistical model derived by backwards stepwise logistic regression.
Variables entered initially: age, sex, diagnosis, lens status, type of procedure, preoperative visual acuity, astigmatism, rejection, other complications, other pathology, and clinic.
Odds ratios >1 (OR>1) indicate increased likelihood that VA≥0.5.
OR<1 indicate reduced likelihood that VA≥0.5.
For categorical variables, the likelihood associated with each factor is compared with a baseline factor (OR=1.00); for example, the influence of diagnosis is relative to keratoconus.
For continuous variables, such as astigmatism, OR>1 indicates increased likelihood that VA≥0.5 with increasing values of the variable. Conversely, OR<1 indicates decreased likelihood that VA≥0.5 with increasing values of the variable.
Procedure
    PKP1.00
    Triple−1.540.560.0070.220.070.65
    Other−0.600.770.430.550.122.46
Preoperative visual acuity0.990.360.0062.671.335.44
Astigmatism−1.410.420.0010.240.110.55
Other pathology
    No1.00
    Yes−4.630.65<0.0010.010.0030.04
    Not known−2.860.79<0.0010.060.010.27
Clinic
    A1.00
    B0.660.800.411.940.419.24
    C−0.440.970.650.650.104.32
    D3.040.72<0.00120.802.0885.16
    E3.390.75<0.00129.526.83127.61
Constant4.851.37