Risk factors for fracture in adult kidney transplant recipients

Table 1 Characteristics of kidney transplant recipients classified by major fracture status¹n (%)

	No fracture (n = 2591)	Major Fracture (n = 132)	P-value
General risk factors
Age (yr)	50.5 (41-61)	56.5 (45-63)	0.01
Women	928 (35.8)	66 (48.5)	0.004
Race/ethnicity			0.40
White	1845 (71.2)	103 (78)
Asian	208 (8.0)	8 (6.1)
Black	198 (7.6)	7 (5.3)
Other2	340 (13.1)	14 (10.6)
Diabetes	673 (25.6)	40 (30.3)	0.27
Fall with hospitalization in the year prior to the transplant date	92 (3.6)	8 (6.1)	0.15
Major fracture prior to the transplant date3
Transplant specific risk factors
Length of time on dialysis prior to transplant (measured in years)4	2.8 (1.2-5.4)	2.7 (0.92-5.1)	0.56
Type of donor			0.47
Deceased (vs living)	1458 (56.3)	70 (53.0)
Cause of end-stage renal disease5			0.004
Glomerulonephritis	951 (36.7)	39 (29.6)
Cystic kidney disease	385 (14.9)	31 (23.5)
Diabetes	560 (21.6)	37 (28.0)
Other	695 (26.8)	25 (18.9)
Pre-transplant dialysis modality6			0.99
Peritoneal dialysis	701 (27.1)	35 (26.5)
Hemodialysis	1622 (62.6)	83 (62.9)
Pre-emptive	268 (10.3)	14 (11.6)
Donor characteristics
Type of donor			0.47
Deceased (vs living)	1458 (56.3)	70 (53.0)
Donor age (yr)	46 (36-54)	48 (41-55)	0.16
Donor sex			0.73
Women	1295 (50.0)	68 (51.5)

Data are median (interquartile range) or n (%). ¹Major fracture events were comprised of forearm (n = 81), hip (n = 22), proximal humerus (n = 18), and clinical vertebral fractures (n = 13);

²Other was defined as a composite of: Indian Sub-Continent, Pacific Islander, Aboriginal, Mid East/Arabian, Latin American, Other/Multiracial;

³Due to the small number of recipients with a prior major fracture this risk factor was not able to be assessed;

⁴Includes individuals who received a pre-emptive transplant where the time spent on dialysis was defined as 0 years;

⁵Due to the small number of recipients with a major fracture who had renal vascular disease as the cause of their ESRD this category was combined into the other category;

⁶We defined hemodialysis and peritoneal dialysis based on the modality the recipient first received. We defined pre-emptive transplant as no evidence of hemodialysis or peritoneal dialysis prior to transplant. ESRD: End-stage renal disease.

Table 2 Univariable and multivariable analysis of risk factors for major fracture in kidney transplant recipients

Risk factors	Univariable analysis	Multivariable analysis
	HR (95%CI)	HR (95%CI)
Age (per 5 yr increase)	1.13 (1.06-1.21)	1.11 (1.03-1.19)
Sex
Men	Reference
Women	1.65 (1.18-2.33)	1.81 (1.28-2.57)
Race/ethnicity
White	Reference
Asian	0.72 (0.35-1.47)
Black	0.65 (0.30-1.39)
Other1	0.78 (0.44-1.36)
Diabetes (vs none)	1.40 (0.96-2.02)
Fall with hospitalization in the year prior to the transplant date (vs none)	2.00 (0.98-4.09)	1.72 (0.84-3.50)
Major fracture prior to the transplant date2 (vs none)
Length of time on dialysis prior to transplant (measured in years)3	1.06 (0.61-1.84)
Type of donor
Living	0.99 (0.70-1.39)
Deceased	Reference
Cause of end-stage renal disease4
Glomerulonephritis	Reference	Reference
Cystic kidney disease	1.93 (1.20-3.08)	1.73 (1.08-2.78)
Diabetes	1.80 (1.15-2.82)	1.72 (1.09-2.72)
Other	0.92 (0.56-1.53)	0.88 (0.53-1.46)
Pre-transplant dialysis modality5
Hemodialysis	Reference
Peritoneal dialysis	0.99 (0.67-1.47)
Pre-emptive	0.96 (0.54-1.68)
Type of donor
Living	0.99 (0.70-1.39)
Deceased	Reference
Donor age (per 5 yr increase)	1.11 (1.04-1.18)	1.09 (1.02-1.17)
Donor sex
Men	Reference
Women	1.03 (0.73-1.44)

¹Other was defined as a composite of: Indian Sub-Continent, Pacific Islander, Aboriginal, Mid East/Arabian, Latin American, Other/Multiracial;

²Due to the small number of recipients with a prior major fracture this risk factor was not able to be assessed;

³Includes individuals who received a pre-emptive transplant where the time spent on dialysis was defined as 0 years;

⁴Due to the small number of recipients with a major fracture who had renal vascular disease as the cause of their ESRD this category was combined into the other category;

⁵We defined hemodialysis and peritoneal dialysis based on the modality the recipient first received. We defined pre-emptive transplant as no evidence of hemodialysis or peritoneal dialysis prior to transplant. ESRD: End-stage renal disease; HR: Hazard ratio.

Table 3 Characteristics of kidney transplant recipients classified by other fractures status³n (%)

	No fracture (n = 2582)	Other fracture (n = 141)	P-value
General risk factors
Age (yr)	52 (42-61)	54 (44-61)	0.18
Women	944 (36.6)	48 (34.0)	0.55
Race/ethnicity			0.33
White	1838 (71.2)	110 (78.0)
Asian	208 (8.1)	8 (5.7)
Black	198 (7.8)	7 (5.0)
Other1	338 (13.1)	16 (11.4)
Diabetes	656 (25.4)	57 (40.4)	< 0.001
Fall with hospitalization in the year prior to the transplant index	90 (3.5)	10 (7.1)	0.03
Major fracture prior to the transplant date5	69 (2.7)	13 (9.2)	< 0.001
Transplant specific risk factors
Length of time on dialysis prior to transplant (measured in years)2	2.7 (1.1-5.4)	3.0 (1.7-5.3)	0.068
Type of donor
Deceased	1439 (55.7)	89 (63.1)	0.09
Cause of end-stage renal disease			0.003
Glomerulonephritis	958 (37.1)	32 (22.7)
Cystic kidney disease	397 (15.4)	19 (13.5)
Diabetes	555 (21.5)	42 (29.8)
Renal vascular disease	294 (11.4)	23 (16.3)
Other	378 (14.6)	25 (17.7)
Pre-transplant dialysis modality4			0.09
Peritoneal dialysis	694 (26.7)	42 (29.8)
Hemodialysis	1613 (62.5)	92 (65.3)
Pre-emptive	275 (10.7)	7 (5.0)
Donor characteristics
Type of donor
Deceased	1439 (55.7)	89 (63.1)	0.09
Donor age (yr)	46 (36-54)	48 (40-54)	0.13
Donor sex
Women	1298 (50.3)	65 (46.1)	0.33

Data are median (interquartile range) or n (%).

¹Other was defined as a composite of: Indian Sub-Continent, Pacific Islander, Aboriginal, Mid East/Arabian, Latin American, Other/Multiracial;

²Includes individuals who received a pre-emptive transplant where the time spent on dialysis was defined as 0 years; ³Other fracture events were comprised of pelvis (n = 15), ankle (n = 37), patella (n = 8), tibia/fibula (n = 37), rib/sternum (n = 34), and other (femoral shaft, scapula, clavicle; n = 16);

⁴We defined hemodialysis and peritoneal dialysis based on the modality the recipient first received. We defined pre-emptive transplant as no evidence of hemodialysis or peritoneal dialysis prior to transplant;

⁵Prior major fracture had to occur from 1991 to cohort entry (date of transplant).

Table 4 Univariable and multivariable analysis of risk factors for other fracture in kidney transplant recipients

Risk factor	Univariable analysis	Multivariable analysis
	HR (95%CI)	HR (95%CI)
Age (per 5 yr increase)	1.09 (1.02-1.17)	1.03 (0.96-1.10)
Sex
Men	Reference
Women	0.99 (0.63-1.26)	0.97 (0.68-1.39)
Race/ethnicity
White	Reference
Asian	0.67 (0.33-1.37)	0.67 (0.32-1.39)
Black	0.59 (0.27-1.26)	0.47 (0.21-1.02)
Other1	0.82 (0.49-1.39)	0.73 (0.43-1.26)
Diabetes (vs none)	2.2 (1.57-3.08)	2.19 (1.38-3.49)
Fall with hospitalization in the year prior to the transplant date (vs none)	2.37 (1.25-4.52)	2.05 (1.07-3.93)
Length of time on dialysis prior to transplant (measured in years)2	1.06 (1.00-1.12)	1.07 (1.01-1.14)
Type of donor
Living	Reference
Deceased	0.67 (0.47-0.92)
Cause of end-stage renal disease
Glomerulonephritis	Reference	Reference
Cystic kidney disease	1.4 (0.8-2.47)	1.35 (0.76-2.39)
Diabetes	2.47 (1.56-3.91)	1.40 (0.78-2.49)
Renal vascular disease	2.40 (1.41-4.10)	2.11 (1.22-3.65)
Other	2.04 (1.21-3.44)	2.03 (1.20-3.45)
Pre-transplant dialysis modality3
Hemodialysis	Reference
Peritoneal dialysis	1.06 (0.74-1.53)
Pre-emptive	0.43 (0.2-0.92)
Donor age (per 5 yr increase)	1.07 (1.01-1.14)	1.06 (0.99-1.12)
Donor sex
Men	Reference
Women	0.83 (0.6-1.16)

¹Other was defined as a composite of: Indian Sub-Continent, Pacific Islander, Aboriginal, Mid East/Arabian, Latin American, Other/Multiracial;

²Includes individuals who received a pre-emptive transplant where the time spent on dialysis was defined as 0 years;

³We defined hemodialysis and peritoneal dialysis based on the modality they first received. We defined pre-emptive transplant as no evidence of hemodialysis or peritoneal dialysis prior to transplant.