# Table 3 Physicians' ability (c = 58) to correctly guess the diagnosis for different patients' factors (n = 626).

Mean physicians' predictive ability Odds Ratio adjusted for cluster effects Differences between GP
% (SD) ORCE (95% CI) p-value ρ*
Patients' age
<50 yrs (n = 257)    56.4% (1.8%)    1.4 (0.98 to 2.0) p = 0.066 ρ = 0.096
≥50 yrs (n = 369)    50.4% (1.3%)    -   -
Patients' gender
Men (n = 304)    50.7% (1.5%)    0.93 (0.67 to 1.3) p = 0.680 ρ = 0.089
Women (n = 322)    55.0% (1.5%)    -   -
Known patient
Yes (n = 569)    53.1% (0.9%)    1.3 (0.72 to 2.4) p = 0.386 ρ = 0.088
No (n = 57)    47.4% (4.9%)    -   -
New Complaint
Yes (n = 301)    48.5% (1.5%)    0.78 (0.56 to 1.1) p = 0.158 ρ = 0.088
No (n = 325)    54.2% (1.2%)    -   -
Patient feeling anxious
Yes (n = 348)    44.8% (1.3%)    0.46 (0.33 to 0.65) p < 0.0001 ρ = 0.090
No (n = 278)    62.9% (1.5%)    -   -
Life threatening
Yes (n = 104)    65.4% (3.5%)    1.8 (1.1 to 2.8) p = 0.015 ρ = 0.087
No (n = 522)    50.3% (0.1%)    -   -
1. * ρ is the intraclass correlation coefficient (ICC) which corresponds to the proportion of the total observed variance which is related to the lack of independence between measures taken from the same physician. A value of 0 indicates no differences between physicians whereas a value of 1 indicates that the associations are totally dependent on physicians.