The Positive Predictive Value of Hip Fracture Diagnoses and Surgical Procedure Codes in the Danish Multidisciplinary Hip Fracture Registry and the Danish National Patient Registry

Figures & data

Figure 1 Flowchart showing the selection of the study population.

Table 1 Summary of Diagnosis Codes and Performed Procedures Coded in the Danish Multidisciplinary Hip Fracture Registry (DMHFR)

Procedure Coded in DMHFR	Diagnosis Coded in DMHFR
	DS720	DS721	DS722
KNFB* Primary prosthetic replacement of hip joint	159	6	3
KNFJ5* Internal fixation using intramedullary nail	11	86	179
KNFJ6* Internal fixation using plate and screws	21	67	22
KNFJ7* Internal fixation using screws alone	41	3	2
KNFJ 4*, 8*, 9* Internal fixation with all other or combined methods	18	88	44

Notes: *Indicates all possible digit(s) in the subgroups of the classification. E.g. KNFJ5* = KNFJ50, KNFJ51, KNFJ52, KNFJ53, KNFJ54 and KNFJ55.

Table 2 Positive Predictive Value (PPV) of Diagnoses and Procedures Coded in the Danish Multidisciplinary Hip Fracture Registry (DMHFR)

Diagnosis Coded in DMHFR	Total, n	Verified	PPV (95% CI)
DS720 Fracture of neck of femur	250	225	90 (86–93)
DS721 Trochanteric fracture	250	229	92 (87–95)
DS722 Subtrochanteric fracture	250	208	83 (78–88)
Lateral fracture (DS721 + DS722)	500	483	97 (95–98)
Procedure coded in DMHFR
KNFB* Primary prosthetic replacement of hip joint	168	168	100 (98–100)
KNFJ5* Internal fixation using intramedullary nail	276	275	100 (98–100)
KNFJ6* Internal fixation using plate and screws	110	100	91 (84–96)
KNFJ7* Internal fixation using screws alone	46	44	96 (85–99)
KNFJ 4*, 8*, 9* Internal fixation with other or combined methods	150	134	89 (83–94)

Notes: *Indicates all possible digit(s) in the subgroups of the classification. E.g. KNFJ5* = KNFJ50, KNFJ51, KNFJ52, KNFJ53, KNFJ54 and KNFJ55.

Abbreviation: CI, Confidence interval.

Table 3 Positive Predictive Value (PPV) of Diagnoses and Procedures, by Age Group, Coded in the Danish Multidisciplinary Hip Fracture Registry (DMHFR)

Diagnosis Coded in DMHFR	65–74 Years		75–84 Years		> 80 Years
	Total/Verified	PPV (95% CI)	Total/Verified	PPV (95% CI)	Total/Verified	PPV (95% CI)
DS720 Fracture of neck of femur	50/48	96 (86–100)	94/85	90 (83–96)	106/92	87 (79–93)
DS721 Trochanteric fracture	53/50	94 (84–99)	91/82	90 (82–95)	106/97	92 (84–96)
DS722 Subtrochanteric fracture	55/44	80 (67–90)	90/79	88 (79–94)	105/85	81 (72–88)
Lateral fracture (DS721 + DS722)	108/106	98 (93–1.00)	181/172	95 (91–98)	211/205	97 (94–99)
Procedure coded in DMHFR
KNFB* Primary prosthetic replacement of hip joint	31/31	100 (89–100)	68/68	100 (95–100)	69/69	100 (95–100)
KNFJ5* Internal fixation using intramedullary nail	58/57	98 (91–100)	101/101	100 (96–100)	117/117	100 (97–100)
KNFJ6* Internal fixation using plate and screws	27/25	93 (76–99)	39/38	97 (87–100)	44/37	84 (70–93)
KNFJ7* Internal fixation using screws alone	12/12	100 (74–100)	14/14	100 (77–100)	20/18	90 (68–99)
KNFJ 4*, 8*, 9* Internal fixation with other or combined methods	30/25	83 (65–94)	53/47	89 (77–96)	67/62	93 (83–98)

Notes: *Indicates all possible digit(s) in the subgroups of the classification. E.g. KNFJ5* = KNFJ50, KNFJ51, KNFJ52, KNFJ53, KNFJ54 and KNFJ55.

Abbreviation: CI, Confidence interval.

Table 4 Positive Predictive Value (PPV) of Diagnoses and Procedures, by Gender and Hospital Type, Coded in the Danish Multidisciplinary Hip Fracture Registry (DMHFR)

Diagnosis Coded in DMHFR	Male		Female		University Hospital		Regional Hospital
	Total/Verified	PPV (95% CI)	Total/Verified	PPV (95% CI)	Total/Verified	PPV (95% CI)	Total/Verified	PPV (95% CI)
DS720 Fracture of neck of femur	72/67	93 (85–98)	178/158	89 (83–93)	100/87	87 (79–93)	150/138	92 (86–96)
DS721 Trochanteric fracture	84/79	94 (87–98)	166/150	90 (85–94)	100/93	93 (86–97)	150/136	91 (85–95)
DS722 Subtrochanteric fracture	80/66	82 (72–90)	170/142	84 (77–89)	100/75	75 (65–83)	150/133	89 (82–93)
Lateral fracture (DS721 + DS722)	164/161	98 (95–100)	336/322	96 (93–98)	200/196	98 (95–99)	300/287	96 (93–98)
Procedure coded in DMHFR
KNFB* Primary prosthetic replacement of hip joint	44/44	100 (92–100)	124/124	100 (97–100)	65/65	100 (94–100)	103/103	100 (96–100)
KNFJ5* Internal fixation using intramedullary nail	85/85	100 (96–100)	191/190	99 (97–100)	131/131	100 (97–100)	145/144	99 (96–100)
KNFJ6* Internal fixation using plate and screws	38/34	89 (75–97)	72/66	92 (83–97)	26/26	100 (87–100)	84/74	88 (79–94)
KNFJ7* Internal fixation using screws alone	15/15	100 (78–100)	31/29	94 (79–99)	14/13	93 (66–100)	32/31	97 (84–100)
KNFJ 4*, 8*, 9* Internal fixation with other or combined methods	54/46	85 (73–93)	96/88	92 (84–96)	64/58	91 (81–96)	86/76	88 (80–94)

Notes: *Indicates all possible digit(s) in the subgroups of the classification. E.g. KNFJ5* = KNFJ50, KNFJ51, KNFJ52, KNFJ53, KNFJ54 and KNFJ55.

Abbreviation: CI, Confidence interval.

Table 5 Positive Predictive Value (PPV) of Diagnoses Procedures, by Calendar Year, Coded in the Danish Multidisciplinary Hip Fracture Registry (DMHFR)

Diagnosis Coded in DMHFR	2014		2015		2016		2017
	Total/Verified	PPV (95% CI)	Total/Verified	PPV (95% CI)	Total/Verified	PPV (95% CI)	Total/Verified	PPV (95% CI)
DS720 Fracture of neck of femur	59/51	86 (75–94)	60/56	93 (84–98)	69/62	90 (80–96)	62/56	90 (80–96)
DS721 Trochanteric fracture	61/56	92 (82–97)	60/56	93 (84–98)	50/44	88 (76–95)	79/73	92 (84–97)
DS722 Subtrochanteric fracture	62/54	87 (76–94)	56/44	79 (66–88)	59/49	83 (71–92)	73/61	84 (73–91)
Lateral fracture (DS721 + DS722)	123/119	97 (92–99)	116/114	98 (94–100)	109/102	94 (87–97)	152/148	97 (93–99)
Procedure coded in DMHFR
KNFB* Primary prosthetic replacement of hip joint	35/35	100 (90–100)	38/38	100 (91–100)	48/48	100 (93–100)	47/47	100 (92–100)
KNFJ5* Internal fixation using intramedullary nail	66/66	100 (95–100)	59/59	100 (94–100)	58/57	98 (91–100)	93/93	100 (96–100)
KNFJ6* Internal fixation using plate and screws	29/28	97 (82–100)	29/27	93 (77–099)	27/22	81 (62–94)	25/23	92 (74–99)
KNFJ7* Internal fixation using screws alone	9/8	89 (52–100)	13/12	92 (64–100)	13/13	100 (75–100)	11/11	100 (72–100)
KNFJ 4*, 8*, 9* Internal fixation with other or combined methods	43/40	93 (81–99)	37/34	92 (78–98)	32/30	94 (79–99)	38/30	79 (63–90)

Notes: *Indicates all possible digit(s) in the subgroups of the classification. E.g. KNFJ5* = KNFJ50, KNFJ51, KNFJ52, KNFJ53, KNFJ54 and KNFJ55.

Abbreviation: CI, Confidence interval.