Table 1

Diagnostic accuracy characteristics of case definitions based on 284 chart reviewed cases and 100 controls

Definition testedTrue positiveFalse positiveFalse negativeTrue negativeDiagnostic accuracy
95% CI
SensitivitySpecificityPositive predictive value
≥2 555.x codes19688010077
73 to 81
100 (by definition)53
46 to 60
69
63 to 74
≥3 555.x codes18966712281
77 to 85
96
93 to 99
65
58 to 72
74
68 to 79
≥2 555.x codes and ≥1 CD hospitalisation832511316364
59 to 69
42
35 to 50
87
81 to 91
77
68 to 84
≥2 555.x codes and ≥2 CD hospitalisations39715718157
52 to 62
20
15 to 26
96
92 to 98
85
71 to 94
≥2 555.x codes with ≥1 recorded by a gastroenterologist148364815278
74 to 82
76
69 to 82
81
74 to 86
80
74 to 86
≥2 555.x codes with ≥2 recorded by a gastroenterologist140255616379
74 to 83
71
65 to 88
87
81 to 91
85
78 to 90
≥3 555.x codes with ≥2 recorded by a gastroenterologist135256116378
73 to 82
69
62 to 75
87
81 to 91
84
78 to 90
≥2 555.x codes with ≥1 recorded by a gastroenterologist or general surgeon149364715278
74 to 83
76
69 to 82
81
75 to 86
81
74 to 86
2+555.x codes with ≥2 recorded by a gastroenterologist or general surgeon141255516379
75 to 83
72
66 to 78
87
82 to 92
85
80 to 90
2+555.x codes with ≥1 colonoscopy at same time as a 555.x code962210016668
63 to 73
49
42 to 56
88
83 to 93
81
73 to 88
  • True positive: met inclusion criteria and chart confirmed a case.

  • False positive: met inclusion criteria but not chart confirmed a case.

  • Diagnostic accuracy, Sensitivity, Specificity and Positive predictive value are in percent.

  • CD, Crohn's disease.