Clinical validation of immunoglobulin A nephropathy diagnosis in Swedish biopsy registers

Figures & data

Figure 1 Definition of confirmed and likely IgAN.

Abbreviation: IgAN, IgA nephropathy.

Table 1 Characteristics of unique individuals at first IgAN+ renal biopsy (in 127 of 150 randomly selected cases, patient charts were available; 113 of them had a confirmed clinical diagnosis of IgAN)

	All individuals	Confirmed IgAN	Unavailable patient charts
n	127	116	23
Age, years (median, range)	39 (4–79)	39 (4–79)	27 (9–69)
Children <16 years, n (%)	7 (6)	7 (6)	6 (26)
Females, n (%)	33 (26)	30 (26)	5 (22)
Year of first renal biopsy (median, upper range)	2001 (1978–2010)	2001 (1978–2010)	1991 (1980–2010)

Abbreviation: IgAN, IgA nephropathy.

Table 2 Clinical characteristics and laboratory data at the time of first IgAN+ renal biopsy (n=127)

Cause of consultation	n (%)
Infection-related macroscopic hematuria	27 (21)
Macroscopic hematuria (without mention of infection)	10 (8)
Purpura	14 (11)
Malignant hypertension	5 (4)
Nephrotic syndrome	4 (3)
Renal failure	5 (4)
Screening	33 (26)
Joint pain	3 (2)
Flank pain	8 (6)
Other	5 (4)
Family history
Family history of renal disease	20 (16)
Family history of ESRD	9 (7)
Family history of IgAN	8 (6)
Laboratory data
Creatinine (μmol/L; n=110; median [range])	104 (26–986)
GFR (mL/min/1.73m^2; n=114; median [range])	75 (5–173)
CKD 1–2 GFR ≥60 (n; %)	75 (59)
CKD 3 GFR ≥30 and <60 (n; %)	20 (16)
CKD 4 GFR <30 (n; %)	21 (17)
Systolic BP (mmHg; n=102; mean ± SD)	138±22
Diastolic BP (mmHg; n=102; mean ± SD)	83±15
Hypertension (BP >140/80 mmHg) or on antihypertensive treatment (n; %)	59 (46)
Antinuclear antibodies (n=68) (n; %)	6 (5)
Viral hepatitis (n=51) (n; %)	3 (2)
Antineutrophilic cytoplasmic antibodies (n; %)	5 (4)
Microscopic or macroscopic hematuria (n=119)	116 (91)
Significant proteinuria (dU-albumin >1 g/24 h, dU-protein >1.5 g/24 h, U-albumin >1 g/L or U-albumin/creatinine ratio >100 g/mole) (n=98)	56 (44)

Abbreviations: IgAN, IgA nephropathy; ESRD, end-stage renal disease; GFR, glomerular filtration rate; CKD, chronic kidney disease; BP, blood pressure; SD, standard deviation.

Table 3 Renal biopsy findings

Biopsy findings	All individuals	Confirmed IgAN
n	127	116
IgA deposits: moderate or rich amount or moderate or strong fluorescence, n (%)	107 (84)	105 (91)
Mesangial hypercellularity, n (%)	96 (76)	92 (79)
C3 deposits, n (%)	113 (89)	104 (90)
C1q deposits, n (%)	15 (12)	14 (12)

Abbreviation: IgAN, IgA nephropathy.