Table 4.

Absolute numbers of true positives, false negatives, true negatives, false positives, and test positives in an imaginary population of 1000 patients with an 11% prevalence of CHD

Test strategyTrue positives (95% CI)False negatives (95% CI)True negatives (95% CI)False positives (95% CI)Test positives (95% CI)
Unaided clinical judgement91 (80 to 99)19 (30 to 11)543 (505 to 580)347 (385 to 310)443 (403 to 484)
Marburg Heart Score101 (91 to 106)9 (19 to 4)539 (501 to 577)351 (389 to 313)457 (417 to 498)
Triage90 (78 to 98)20 (32 to 12)646 (611 to 679)244 (279 to 211)339 (302 to 379)
Aided clinical judgement100 (79 to 107)10 (31 to 3)595 (538 to 646)295 (352 to 244)382 (324 to 443)
  • CHD = coronary heart disease. For each test strategy the absolute numbers of the true positives among the 110 patients who have CHD, the absolute numbers of true negatives among the 890 patients who do not have CHD, and the absolute numbers of test positives including the respective CIs were calculated using the fractions of true positives, true negatives, test positives, and the respective CIs as obtained in this study. The absolute numbers of false negatives and false positives including the boundaries were calculated by completing the respective 2by2 tables. Please note that by using this approach the number of test positives is similar, but not identical to, the sum of true positives and false positives.