Administrative coding for non-alcoholic fatty liver disease is accurate in Swedish patients

Figures & data

Figure 1. – Flowchart for patient inclusion.

Table 1. Patient characteristics stratified on NAFLD status upon medical chart review.

	All patients (n = 147)	True NAFLD (n = 121)	All False NAFLD (n = 26)	p-value^a	False NAFLD subgroup^§ (n = 12)	p-value^b
Age (yrs) – median (IQR)	55 (39–65)	52 (37–64)	60 (48–70)	0.07^e	67 (48–74)	0.02^e
Male (%)	88 (60)	75 (62)	13 (50)	0.26^f	5 (42)	0.17^f
ALT – median (IQR), u/L	62 (34–95)	64 (41–97)	47 (25–84)	0.13^e	44 (25–69)	0.10^e
AST – median (IQR), u/L	44 (29–66)	44 (29-59)	58 (28–76)	0.27^e	40 (19–71)	0.64^e
Platelet count – mean (SD), x10^9/L	237 (±76)	243 (±78)	212 (±65)	0.08^g	232 (±74)	0.66^g
Creatinine – mean µmol/L (SD)	71 (±16)	70 (±16)	74 (±16)	0.28^g	76 (±15)	0.29^g
FIB-4 – median (IQR)	1.4 (0.8–2.3)	1.3 (0.8-1.9)	2.2 (1.3–2.9)	<0.001^e	1.9 (1.0–2.9)	0.16^e
BMI – mean (range) (SD), kg/m^2	31.9 (±6.0)	32.0 (±5.8)	31.3 (±7.0)	0.59^g	31.8 (±7.6)	0.93^g
BMI ≥30 kg/m^2 (%)	92 (64)	78 (69)	14 (54)	0.22^f	5 (42)	0.09^f
Obesity coding^c (%)	69 (47)	62 (51)	7 (27)	0.02^f	3 (25)	0.10^f
T2D^d (%)	47 (32)	43 (36)	4 (15)	0.03^f	2 (17)	0.046^f

ALT: alanine transaminase; AST: aspartate transaminase; BMI: body mass index; CI: confidence interval; FIB-4: fibrosis 4 score; SD: standard deviation; T2D: type 2 diabetes; NAFLD: non-alcoholic fatty liver disease. ^aComparing patients with true NAFLD and all false NAFLD. ^bComparing patients with true NAFLD and false NAFLD after exclusions for other liver- and alcohol-related coding. ^cE65-66. ^dE11. ^eMann-Whitney U-test, ^fChi-squared test, ^gStudent’s t-test. ^§Patients with coding for NAFLD, alcohol overconsumption on medical chart review, but no coding for alcohol overconsumption.

Table 2. Positive predictive values for the ICD-10 code K76.0 and different associated subgroups.

ICD-10 Codes	Patients, n	PPV	(95% CI)
NAFLD (K76.0)	147	0.82 (121/147)	(0.76–0.89)
NAFLD (K76.0) excluding coding for other liver diseases	136	0.89 (121/136)	(0.84–0.94)
NAFLD (K76.0) excluding coding for other liver diseases and alcohol-related coding	133	0.91 (121/133)	(0.87–0.96)
Validity of the K76.0 code in patients with relevant comorbidities^a
NAFLD (K76.0) and T2D (E11)	47	0.96 (45/47)	(0.89–1.00)
NAFLD (K76.0) and obesity (E65-E66)	69	0.95 (62/65)	(0.90–1.00)
Validity of the K76.0 code at specific hospital departments^a
NAFLD diagnosis at gastroenterology or hepatology departments	117	0.92 (95/103)	(0.87–0.97)
NAFLD diagnosis at other departments^b	30	0.87 (26/30)	(0.74–1.00)

ICD-10: International Classification of Disease 10^th revision; NAFLD: non-alcoholic fatty liver disease; T2D: type 2 diabetes; PPV: positive predictive value; CI: confidence interval. ^aFor the subgroups based on comorbidities and clinic of first K76.0 diagnosis, exclusions for other liver-related coding and alcohol-related coding were made before final calculations. ^bEmergency care unit, Pediatric unit, Internal medicine unit, or Surgical unit.