Validity of data in the Danish Colorectal Cancer Screening Database

Figures & data

Table 1 Categories of codes for diagnoses and procedures included in the validation of the DCCSD

Category	Code
Clean colon	AFX02C, AFX02D
Colorectal cancer	DC180, DC182, DC183, DC184, DC185, DC186, DC187, DC189, DC209
Polyps/benign tumors	DD120, DD122, DD123A, DD123, DD123B, DD124, DD125, DD126C, DD128
Colonoscopy performed	KUJF32, KUJF35
Overall completeness of colonoscopy	ZPY1A0, ZPY1A1, ZPY1A10, ZPY1A11, ZPY1A12, ZPY1A13, ZPY1A14, ZPY1A15, ZPY1A18
Incomplete colonoscopy	ZPY1A1, ZPY1A10, ZPY1A11, ZPY1A12, ZPY1A13, ZPY1A14, ZPY1A15, ZPY1A18
Polypectomy	KJFA15, KJFA55A, KJFA55B, KJGA05, KJGA52A, KJGA52B
Tumor tissue left behind	ZPY1B01, ZPY1B02
Number of polyps seen	ZPY1Cnn, ZPY1C99
Lost polyps	ZPY1D00, ZPY1Dnn, ZPY1D99
Risk group of polyps	ZPY1E01, ZPY1E02, ZPY1E03

Abbreviation: DCCSD, Danish Colorectal Cancer Screening Database.

Table 2 Validity of categories of colorectal cancer screening codes in the DCCSD compared with hospital records, n=136

Categories	Agreement, % (95% CI); a/n	Sensitivity, % (95% CI); tp/(tp+fn)	Specificity, % (95% CI); tn/(tn+fp)	PPV, % (95% CI); tp/(tp+fp)	NPV, % (95% CI); tn/(tn+fn)
Clean colon	82.4 (74.9–88.4); 112/136	69.0 (56.9–79.5); 49/(49+22)	96.9 (89.3–99.6); 63/(63+2)	96.1 (86.5–99.5); 49/(49+2)	74.1 (63.5–83.0); 63/(63+22)
Colorectal cancer	97.1 (92.6–99.2); 132/136	72.7 (39.0–94.0); 8/(8+3)	99.2 (95.6–100.0); 124/(124/1)	88.9 (51.8–99.7); 8/(8+1)	97.6 (93.3–99.5); 124/(124+3)
Polyps/benign tumors	90.4 (84.2–94.8); 123/136	84.7 (73.0–92.8); 50/(50+9)	94.8 (87.2–98.6); 73/(73+4)	92.6 (82.1–97.9); 50/(50+4)	89.0 (80.2–94.9); 73/(73+9)
Colonoscopy performed	96.3 (91.6–98.8); 131/136	98.5 (94.6–99.8); 130/(130+2)	25.0 (0.6–80.6); 1/(1+3)	97.7 (93.5–99.5); 130/(130+3)	33.3 (0.8–90.6); 1/(1+2)
Overall completeness of colonoscopy	92.6 (86.9–96.4); 126/136	93.9 (88.4–97.3); 124/(124+8)	50.0 (6.8–93.2); 2/(2+2)	98.4 (94.4–99.8); 124/(124+2)	20.0 (2.5–55.6); 2/(2+8)
Incomplete colonoscopy	96.3 (91.6–98.8); 131/136	60.0 (26.2–87.8); 6/(6+4)	99.2 (95.7–100.0); 125/(125+1)	85.7 (42.1–99.6); 6/(6+1)	96.9 (92.3–99.1); 125/(125+4)
Polypectomy	95.6 (90.6–98.4); 130/136	92.1 (82.4–97.4); 58/(58+5)	98.6 (92.6–100.0); 72/(72+1)	98.3 (90.9–100.0); 58/(58+1)	93.5 (85.5–97.9); 72/(72+5)
Tumor tissue left behind	87.5 (80.7–92.5); 119/136	75.0 (63.0–84.7); 51/(51+17)	100.0 (94.7–100.0); 68/(68+0)	100.0 (93.0–100.0); 51/(51+0)	80.0 (69.9–87.9); 68/(68+17)
Number of polyps seen	93.4 (87.8–96.9); 127/136	89.4 (79.4–95.6); 59/(59+7)	97.1 (90.1–99.7); 68/(68+2)	96.7 (88.7–99.6); 59/(59+2)	90.7 (81.7–96.2); 68/(68+7)
Lost polyps	88.2 (81.6–93.1); 120/136	81.5 (68.6–90.7); 44/(44+10)	92.7 (84.8–97.3); 76/(76+6)	88.0 (75.7–95.5); 44/(44+6)	88.4 (79.7–94.3); 76/(76+10)
Risk group of polyps	83.8 (76.5–89.6); 114/136	69.6 (55.9–81.2); 39/(39+17)	93.8 (86.0–97.9); 75/(75+5)	88.6 (75.4–96.2); 39/(39+5)	81.5 (72.1–88.9); 75/(75+17)

Notes: a, number in agreement; n, number in total.

Abbreviations: CI, confidence interval; fn, false negatives; fp, false positives; NPV, negative predictive value; PPV, positive predictive value; tn, true negatives; tp, true positives.

Table 3 Validity of specific colorectal cancer screening codes in the DCCSD compared with hospital records, n=136

	DCCSD code	Agreement, % (95% CI); a/n	Specificity, % (95% CI); tn/(tn+fp)	NPV, % (95% CI); tn/(tn+fn)
Clean colon at colonoscopy	AFX02C	83.8 (76.5–89.6); 114/136	97.1 (89.9–99.6); 67/(67+2)	77.0 (66.8–85.4); 67/(67+20)
Clean colon at CT colonography	AFX02D	97.8 (93.7–99.5); 133/136	100.0 (97.2–100.0); 131/(131+0)	97.8 (93.6–99.5); 131/(131+3)
Cancer in cecum	DC180	100.0 (97.3–100.0); 136/136	100.0 (97.3–100.0); 135/(135+0)	100.0 (97.3–100.0); 135/(135+0)
Cancer in ascending colon	DC182	99.3 (96.0–100.0); 135/136	100.0 (97.3–100.0); 135/(135+0)	99.3 (96.0–100.0); 135/(135+1)
Cancer in transverse colon	DC184	99.3 (96.0–100.0); 135/136	100.0 (97.3–100.0); 134/(134+0)	99.3 (95.9–100.0); 134/(134+1)
Cancer in sigmoid colon	DC187	98.5 (94.8–99.8); 134/136	99.2 (95.9–100.0); 131/(131+1)	99.2 (95.9–100.0); 131/(131+1)
Colorectal cancer unspecified	DC189	98.5 (94.8–99.8); 134/136	98.5 (94.8–99.8); 134/(134+2)	100.0 (97.3–100.0); 134/(134+0)
Rectal cancer	DC209	99.3 (96.0–100.0); 135/136	100.0 (97.3–100.0); 133/(133+0)	99.3 (95.9–100.0); 133/(133+1)
Benign tumor in cecum	DD120	96.3 (91.6–98.8); 131/136	99.2 (95.8–100.0); 128/(128+1)	97.0 (92.4–99.2); 128/(128+4)
Benign tumor in ascending colon	DD122	97.1 (92.6–99.2); 132/136	99.2 (95.8–100.0); 130/(130+1)	97.7 (93.5–99.5); 130/(130+3)
Benign tumor in right colic flexure	DD123A	98.5 (94.8–99.8); 134/136	99.2 (95.9–100.0); 132/(132+1)	99.2 (95.9–100.0); 132/(132+1)
Benign tumor in transverse colon	DD123	98.5 (94.8–99.8); 134/136	99.2 (95.8–100.0); 129/(129+1)	99.2 (95.8–100.0); 129/(129+1)
Benign tumor in left colic flexure	DD123B	97.8 (93.7–99.5); 133/136	98.5 (94.7–99.8); 131/(131+2)	99.2 (95.9–100.0); 131/(131+1)
Benign tumor in descending colon	DD124	100.0 (97.3–100.0); 136/136	100.0 (97.3–100.0); 133/(133+0)	100.0 (97.3–100.0); 133/(133+0)
Benign tumor in sigmoid colon	DD125	93.4 (87.8–96.9); 127/136	97.9 (92.5–99.7); 92/(92+2)	92.9 (86.0–97.1); 92/(92+7)
Multiple benign tumors in the colon	DD126C	99.3 (96.0–100.0); 135/136	100.0 (97.3–100.0); 133/(133+0)	99.3 (95.9–100.0); 133/(133+1)
Benign tumor in the rectum	DD128	94.9 (89.7–97.9); 129/136	97.5 (92.9–99.5); 118/(118+3)	96.7 (91.8–99.1) 118/(118+4)
Colonoscopy	KUJF32	87.5 (80.7–92.5); 119/136	75.0 (47.6–92.7); 12/(12+4)	48.0 (27.8–68.7); 12/(12+13)
Colonoscopy with biopsy	KUJF35	89.7 (83.3–94.3); 122/136	90.3 (83.7–94.9); 112/(112+12)	98.2 (93.8–99.8); 112/(112+2)
Complete colonoscopy	ZPY1A0	91.9 (86.0–95.9); 125/136	71.4 (41.9–91.6); 10/(10+4)	58.8 (32.9–81.6); 10/(10+7)
Not complete colonoscopy	ZPY1A1	98.5 (94.8–99.8); 134/136	100.0 (97.3–100.0); 133/(133+0)	98.5 (94.8–99.8); 133/(133+2)
Endoscopic polypectomy, large intestine	KJFA15	95.6 (90.6–98.4); 130/136	96.3 (89.6–99.2); 78/(78+3)	96.3 (89.6–99.2); 78/(78+3)
Endoscopic mucosal resection, large intestine	KJFA55A	98.5 (94.8–99.8); 134/136	99.3 (95.9–100.0); 133/(133+1)	99.3 (95.9–100.0); 133/(133+1)
Rectoscopic polypectomy, rectum	KJGA05	94.9 (89.7–97.9); 129/136	98.4 (94.3–99.8); 123/(123+2)	96.1 (91.1–98.7); 123/(123+5)
Tumor tissue left behind	ZPY1B01	94.9 (89.7–97.9); 129/136	99.2 (95.8–100.0); 128/(128+1)	95.5 (90.5–98.3); 128/(128+6)
No tumor tissue left behind	ZPY1B02	89.7 (83.3–94.3); 122/136	98.7 (92.8–100.0); 74/(74+1)	87.1 (78.0–93.4); 74/(74+11)
Number (nn) polyps seen	ZPY1Cnn	90.4 (84.2–94.8); 123/136	97.1 (90.1–99.7); 68/(68+2)	86.1 (76.5–92.8); 68/(68+11)
No lost polyps	ZPY1D00	87.5 (80.7–92.5); 119/136	94.3 (87.2–98.1); 83/(83+5)	87.4 (79.0–93.3); 83/(83+12)
Largest polyp lost, size in mm	ZPY1Dnn	96.3 (91.6–98.8); 131/136	96.9 (92.3–99.2); 126/(126+4)	99.2 (95.7–100.0); 126/(126+1)
High-risk polyps removed	ZPY1E01	92.6 (86.9–96.4); 126/136	97.5 (93.0–99.5); 119/(119+3)	94.4 (88.9–97.7); 119/(119+7)
Medium-risk polyps removed	ZPY1E02	91.2 (85.1–95.4); 124/136	97.4 (92.7–99.5); 114/(114+3)	92.7 (86.6–96.6); 114/(114+9)
Low-risk polyps removed	ZPY1E03	88.2 (81.6–93.1); 120/136	93.8 (87.5–97.5); 105/(105+7)	92.1 (85.5–96.3); 105/(105+9)

Notes: a, number in agreement; n, number in total.

Abbreviations: CI, confidence interval; CT, computed tomography; fn, false negatives; fp, false positives; NPV, negative predictive value; tn, true negatives; tp, true positives.

Figure 1 Flowchart of hospital records.