Table 6.

Validity of variables registered in the nonmelanoma skin cancer database. Verified in medical records

	NMSC database:	Medical record		Total	Missing	PPV % (95% CI)	NPV % (95% CI)	Sensitivity % (95% CI)	Specificity % (95% CI)
		Yes	No
First skin cancer ever (incident case)	Yes	31	1	32		31/32 = 97 (85–100)		31/33 = 97 (85–100)
	No	2	32	34			32/34 = 94 (80–99)		32/34 = 94 (80–99)
	Unknown		1
	Total	33	34
Tumor registered is a new primary tumor	Yes	67	1	68	1	67/68 = 99 (92–100)		67/67 = 100 (95–100)
	No	0	9	9			9/9 = 100 (66–100)		9/10 = 90 (55–100)
	Total	67	10
Localization of tumor		75*	3*	78		75/78 = 96 (89–99)
Size		29*	5*	34	44	29/34 = 85 (69–95)
Treatment date		71*	7*	78		71/78 = 91 (82–96)
Treatment modality overall	Total	73*	4*	77		73/77 = 95 (87–99)
	missing				1
Curettage ± cautery	Yes	62	3	65		62/65 = 95 (87–99)		62/63 = 98 (91–100)
	No	1	11	12			11/12 = 92 (62–100)		11/14 = 79 (49–95)
	Total	63	14
Other treatments incl. excision, photodynamic therapy, imiquimod creme	Yes	2	1	3		2/3 = 67 (9–99)		2/4 = 50 (7–93)
	No	2	72	74			72/74 = 97 (91–100)		72/73 = 99 (93–100)
	Total	4	73
Referred to hospital treatment	Yes	9	0	9		9/9 = 100 (66–100)		9/9 = 100 (66–100)
	No	0	68	68			68/68 = 100 (95–100)		68/68 = 100 (95–100)
	Total	9	68
Recurrence at 1st or 2nd follow-up visit	Yes	3	0	3		3/3 = 100 (29–100)		3/4 = 75 (19–99)
	No	1	43	44			43/44 = 98 (88–99)		43/43 = 100 (92–100)
	Total	4	43		3
	missing	4	11
Complications in relation to treatment	Yes	2	0	2		2/2 = 100 (16–10)		2/3 = 67 (9–99)
	No	1	51	52			51/52 = 98 (90–100)		51/51 = 100 (93–100)
	Total	3	51
	missing	0	8		3

Notes: Confirmed in medical record (yes/no).

Abbreviations: CI, confidence interval; NPV, Negative predictive value; PPV, Positive predictive value.