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Table 4 Influence of pretest expectations on interpretation, posttest probability estimates and management after abnormal results.

From: Pretest expectations strongly influence interpretation of abnormal laboratory results and further management

  Test interpretation Posttest probability Management
  = normal = no disease = no action§
  odds ratio (95% CI) odds ratio (95% CI) odds ratio (95% CI)
Reason for ordering lab tests p = 0.067 p = 0.52 p = 0.06
   exclude disease 1 1 1
   reassure patient 1.1 (0.63-1.83) 1.46 (0.67-3.17) 2.25 (1.08-4.66)
   confirm diagnosis 0.59 (0.37-0.93) 0.82 (0.42-1.59) 0.80 (0.46-1.40)
Pretest probability estimate p < 0.001 p < 0.001 p = 0.19
   definitely no disease 1 1 1
   probably no disease 1.13 (0.56-2.26) 0.35 (0.11-1.08) 1.67 (0.64-4.32)
   maybe 0.49 (0.24-1.03) 0.20 (0.06-0.63) 1.11 (0.41-3.00)
   probably disease 0.33 (0.15-0.73) 0.07 (0.02-0.23) 1.75 (0.59-5.17)
   definitely disease 0.18 (0.07-0.52) 0.04 (0.01-0.23) 2.88 (0.79-10.59)
Test interpretation N/A* p < 0.001 p < 0.001
   normal   1 1
   possibly abnormal   0.09 (0.06-0.15) 0.20 (0.10-0.40)
   abnormal   0.01 (0.005-0.02) 0.43 (0.25-0.72)
Posttest probability estimate N/A* N/A* p < 0.001
   definitely no disease    1
   probably no disease    0.48 (0.26-0.89)
   maybe    0.14 (0.07-0.32)
   probably disease    0.07 (0.03-0.16)
   definitely disease    0.09 (0.04-0.23)
  1. N = 742
  2. *N/A not applicable
  3. Goodness-of-fit: Chi-square = 5.29, p = 0.73, Chi-square = 7.12, p = 0.52, § Chi-square = 5.70, p = 0.68