Validating surgical procedure codes for inflammatory bowel disease in the Swedish National Patient Register

Table 3 Positive predictive value and sensitivity of IBD-related surgical procedure codes in the Swedish National Patient Register stratified by type of surgery and year

Codes	Abdominal	Perianal	Other IBD	1966–1996	1997–2014	Total
Code in chart	67	40	57	85	79	164
Code in chart but missing in NPR	2	4	3	8	1	9
Code in NPR	68	36	54	78	80	158
Code in NPR but missing in chart	3	0	0	1	2	3
Code in chart and NPR	65	36	54	77	78	155
Correct code in chart and NPR	64	36	53	76	77	153
Correct code in chart but false in NPR	1	0	1	1	1	2
PPV (95%CI)	94.1 (88.7–98.6) 64/68	100 (100–100) 36/36	98.1 (93.1–100) 53/54	97.4 (92.7–100) 76/78	96.2 (92.9–100) 77/80
Sensitivity (95%CI)	97.0 (91.9–100) 65/67	90.0 (81.8–100) 36/40	94.7 (88.9–100) 54/57	90.6 (84.6–100) 77/85	98.7 (95.0–100) 78/79

CI Confidence interval, IBD Inflammatory bowel disease, NPR National patient register, PPV Positive predictive value Codes in the patient charts but missing in the NPR registered in 1996 or earlier consisted of six perianal procedure codes (KVÅ, 4999 - Other operation on anus or perianal tissue) and two abdominal procedure codes (KVÅ, 4642 - Ileocaecal resection; KVÅ, 4611 - Laparatomy and closure of a fistula to the bowel wall). One code registered in 1997 or later was missing (NOMESCO, JFH20 - Proctocolectomy with ileostomy)

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