Background
Methods
Study design
Outcome and predictors
Sample size
Statistical analysis
Imputation
Derivation
Validation
Results
Imputation
Model development
Derivation
Characteristics | Non-appendicitis
n = 155 | Appendicitis
n = 241 | OR (95% CI) |
p value |
---|---|---|---|---|
Demographic | ||||
Age (year), mean (SD) | 33.8 (11.9) | 37.9 (15.9) | < 0.001 | |
Age group | ||||
< 40 | 99 (63.9) | 140 (58.1) | 1 | 0.251 |
≥ 40 | 56 (36.1) | 101 (41.9) | 1.3(0.8–1.9) | |
Sex, number, (%) | ||||
Male | 39 (25.2) | 93 (38.6) | 1.9(1.2–2.9) | < 0.001 |
Female | 116 (74.8) | 148 (61.4) | 1 | |
BMI, mean (SD) | 22.4 (3.9) | 22.95 (4.7) | 0.230 | |
Symptoms | ||||
First location of pain | ||||
Epigastrium | 40 (25.8) | 102 (42.3) | 2.2(1.4–3.4) | < 0.001 |
Periumbilical | 24 (15.5) | 31 (12.9) | 1.1(0.6–1.9) | |
Other | 91 (58.7) | 108 (44.8) | 1 | |
Type of pain | ||||
Dull aching, constant | 49 (31.6) | 82 (34.0) | 1.1(0.7–1.7) | 0.620 |
Colicky | 106 (68.4) | 159 (65.9) | 1 | |
Migration of pain | ||||
Absence | 108 (69.7) | 111 (46.1) | 1 | < 0.001 |
Presence | 47 (30.3) | 130 (53.9) | 2.7(1.8–4.1) | |
Onset | ||||
Insidious | 120 (77.4) | 146 (60.6) | 1 | < 0.001 |
Sudden | 35 (22.6) | 95 (39.4) | 2.2(1.4–3.5) | |
Progression of pain | ||||
Yes | 113 (72.9) | 223 (92.5) | 4.6(2.5–8.4) | |
No | 42 (27.1) | 18 (7.5) | 1 | < 0.001 |
Right lower quadrant pain at presentation | ||||
Yes | 140 (90.3) | 239 (99.2) | 12.8(2.9–56.8) | |
No | 15 (9.7) | 2 (0.8) | 1 | < 0.001 |
Time of pain before presentation (hours) | ||||
≤ 48 | 126 (81.3) | 204 (84.7) | 1.3(0.7–2.2) | 0.382 |
> 48 | 29 (18.7) | 37 (15.4) | 1 | |
Time of right lower quadrant pain before presentation (hours) | ||||
≤ 12 | 67 (43.2) | 107 (44.4) | 1.1(0.7–1.6) | 0.820 |
> 12 | 88 (56.8) | 134 (55.6) | 1 | |
Nausea or vomiting | ||||
Yes | 64 (41.3) | 141 (58.5) | 2.0(1.3–3.0) | |
No | 91 (58.7) | 100 (41.5) | 1 | < 0.001 |
Aggravation of pain by cough or movement | ||||
Yes | 88 (56.8) | 199 (82.6) | 3.6(2.3–5.7) | |
No | 67 (43.2) | 42 (17.4) | 1 | < 0.001 |
Anorexia | ||||
Yes | 118 (76.1) | 164 (68.1) | 0.7(0.4–1.1) | 0.083 |
No | 37 (23.9) | 77 (31.9) | 1 | |
Fever | ||||
Yes | 135 (87.1) | 154 (63.9) | 0.3(0.2–0.5) | < 0.001 |
No | 20 (12.9) | 87 (36.1) | ||
Bowel sound | ||||
Increase | 20 (12.9) | 37 (15.4) | 1.4(0.8–2.5) | 0.044 |
Decrease | 16 (10.3) | 45 (18.7) | 2.1(1 .1–3.9) | |
Normal | 119 (76.8) | 159 (65.9) | 1 | |
Body temperature (°C) | ||||
< 37.8 | 146 (94.2) | 176 (73.0) | 1 | < 0.001 |
≥ 37.8 | 9 (5.8) | 65 (26.9) | 5.9 (2.8–12.4) | |
Tenderness at right lower quadrant | ||||
Yes | 137 (88.4) | 240 (99.6) | 31.5 (4.2–238.8) | < 0.001 |
No | 18 (11.6) | 1 (0.4) | 1 | |
Rebound tenderness | ||||
Yes | 37 (23.9) | 155 (64.3) | 5.8(3.7–9.1) | < 0.001 |
No | 118 (76.1) | 86 (35.7) | 1 | |
Guarding | ||||
Yes | 26 (16.8) | 82 (34.0) | 2.6(1.6–4.2) | < 0.001 |
No | 129 (83.2) | 159 (65.9) | 1 | |
Laboratory results | ||||
WBC (cell/mm3) | ||||
≤ 10,000 | 55 (35.5) | 26 (10.8) | 1 | < 0.001 |
> 10,000 cell/mm3
| 100 (64.5) | 215 (89.2) | 4.6(2.7–7.7) | |
Neutrophil (%) | ||||
≤ 75% | 80 (51.6) | 54 (22.4) | 1 | < 0.001 |
> 75% | 75 (48.4) | 187 (77.6) | 3.7(2.4–5.8) |
Domain | Parameters | Coefficient | SE |
p value | OR(95%CI) | Scoring |
---|---|---|---|---|---|---|
Symptoms | Progression of pain | 1.04 | 0.4 | 0.007 | 2.8 (1.3–5.9) | 1.04 |
Aggravation of pain by cough or movement | 0.78 | 0.3 | 0.009 | 2.2 (1.2–3.8) | 0.78 | |
Migration of pain | 0.80 | 0.3 | 0.004 | 2.6 (1.3–3.7) | 0.77 | |
Signs | Body temperature ≥ 37.8 °C | 1.64 | 0.5 | < 0.001 | 5.1 (2.1–12.1) | 1.64 |
Rebound tenderness | 1.53 | 0.3 | < 0.001 | 4.6 (2.7–7.7) | 1.53 | |
Lab results | WBC > 10,000 cell/mm3
| 0.91 | 0.3 | 0.005 | 2.6 (1.3–5.0) | 0.91 |
Neutrophil > 75% | 0.69 | 0.3 | 0.010 | 2.3 (1.2–4.1) | 0.69 | |
Constant | − 3.37 | |||||
Total | 3.99 |
Model performance
Score | Risk groups | Score development for derivative phase | ||||||
---|---|---|---|---|---|---|---|---|
Outcome | % sensitivity (95% CI) | % specificity (95% CI) | LR+ (95% CI) | LR- (95% CI) | Post-positive test odds (%) | |||
AP | Non-AP | |||||||
<− 0.64 | Very low | 25 | 85 | 100.00 | 0 | 1.00 | 0 | 61.80 |
− 0.64 to 0.84 | Low risk | 61 | 51 | 89.75 (85.25–93.26) | 54.97 (46.67–63.06) | 1.98 (1.65–2.37) | 0.19 (0.13–0.28) | 76.00 (73.00–79.00) |
0.85 to 1.74 | Moderate | 64 | 12 | 64.08 (57.73–70.09) | 88.08 (81.82–92.78) | 5.25 (3.39–8.13) | 0.41 (0.34–0.49) | 89.00 (85.00–93.00) |
> 1.74 | High | 91 | 7 | 37.96 (31.86–44.36) | 95.36 (90.68–98.12) | 8.36 (3.96–18.00) | 0.65 (0.59–0.72) | 93.00 (86.00–97.00) |
Validation
Internal validation
External validation
Characteristics | RA (n = 396) | TS (n = 152) | CP (n = 178) |
---|---|---|---|
Mean age (SD), years | 36.3(14.6) | 35.6(16 .9) | 42.9(16.8) |
Men | 132 (35.8%) | 40 (26.4%) | 71 (39.9%) |
Symptoms | |||
Progression of pain | 336 (84.8%) | 98 (64.5%) | 147 (82.6%) |
Aggravation of pain | 287 (72.5%) | 78 (51.4%) | 104 (58.4%) |
Migration of pain | 177 (44.7%) | 73 (48.0%) | 125 (70.2%) |
Signs | |||
Body temperature ≥ 37.8 °C | 74 (18.7%) | 30 (19.7%) | 67 (37.6%) |
Rebound tenderness | 192 (48.5%) | 65 (42.8%) | 127 (71.3%) |
Laboratory | |||
WBC | 315 (79.6%) | 125 (82.2%) | 141 (79.2%) |
Neutrophil | 262 (66.2%) | 115 (75.7%) | 124 (69.7%) |
Prevalence of appendicitis | 245/396 (61.8%) | 74/152 (48.7%) | 137/178 (76.9%) |