Discussion:
In this retrospective study, vertebral fragility fractures were detected
in 56.4% (n=114) of the patients. Forty-six (40.3%) patients with VF
had normal DEXA. Osteoporosis and osteopenia were observed in 20% and
35.6% of the whole study group. Diabetic patients had lower BMD levels
and Z scores both in the femoral neck and lumbar spine.
Age and BMI, which have already known as predictive factors of
osteoporosis in the general population, were found as the factors
associated with femoral neck BMD scores in renal transplant recipients
in our study. Techawathanawanna et al. also stated that the decreasing
BMI and increasing age were correlated with osteoporosis of the hip
region [3].
The standardized incidence ratio of vertebral fractures was 23.1% in
Vautour et al.’s study [24]. Vertebral fractures were detected in
1.8% of patients in the O’Shaughnessy et al. study [25]. On the
other hand, in Nam et al., Durieux et al., Vautour et al., Schreiber et
al., Patel et al., and Pichette et al. study the prevalence of VF was
38.5%, 28.8%, 15.1%, 14.3%, 9.1%, and 5.7%, respectively [4, 17,
18, 23, 24, 27]. While Nam et al. [23] and Patel et al. [18]
evaluated VF respectively with X-ray morphometric criteria and
semiautomated method, the rest of the studies used a semiquantitative
method. This wide distribution rate among studies on vertebral fracture
frequency can be attributed to different definition criteria in the
fracture decision.
Increased fracture risk was associated with diabetes mellitus in
previous reports [25, 28]. In Vautour et al. study [24],
increasing age and diabetes as the cause of end-stage renal disease were
found as independent predictors of overall fracture risk. While the
standardized incidence ratio of vertebral fracture was 33.5% in the
diabetic patient, it was 21.2% in the non-diabetic group [24].
While the presence of diabetes was not associated with vertebral
fractures in our study, diabetic patients had lower BMD levels both in
the femoral neck and lumbar spine.
Low BMD in the femoral neck and lumbar spine was associated with an
increased risk of vertebral fractures [23]. In our study, femoral
neck Z scores were found to be associated with vertebral fractures.
In a study with 238 kidney transplant recipients, patients with
osteoporosis were found to have a 3.5-fold increased risk of fracture
than patients with normal BMD [5]. Contrary to Nam et al. study
[23], BMD levels showed no significant differences between patients
with VF and without VF in our study. In the Marcel et al. study,
vertebral fractures were primarily observed in osteoporotic patients,
but 43% of patients with VF had normal lumbar BMD [6]. In our
study, the VF ratio in patients with normal BMD was 40.3%. Although our
osteopenia and osteoporosis rate is lower than most previous reports,
lower prevalences have been reported [5, 17]. This difference
between studies may be attributed to false signals from extra‐osseous
calcifications or falsely high values obtained from unrecognized
mechanical bone deformation or pre‐existing renal osteodystrophy.
Lumbar BMD losses have been reported as 3–10% in the first six months
following kidney transplantation [9]. Although there are no
well-established therapeutic approaches to prevent early
post-transplantation bone loss, the most recommended manners to provide
bone anabolic effects in renal transplant recipients are; minimizing the
dose of corticosteroids and using vitamin D supplements, active vitamin
D (calcitriol or alfacalcidol), or bisphosphonates [29-31]. In
addition, determining the high-risk group for fractures with routine
vertebral radiological imaging can be helpful to decide giving treatment
to renal transplant recipients in the early period.
The major limitation of this study is that the evaluation of vertebral
fractures was made using a semiquantitative method. Secondly, we
evaluated retrospectively, limiting our ability to determine the exact
timing of the occurrence of VF, whether it had occurred before
transplantation. To determine the occurrence time of VF, prospective
studies with long-term follow-up with a routine evaluation of spine
X-rays at regular intervals before and after transplantation are needed.
In this study, a high vertebral fracture prevalence was found regardless
of osteoporosis and CRF duration. Vertebral fractures were observed more
frequently in patients with normal BMD. Besides the BMD evaluation,
vertebral fracture evaluation may help a proper therapy decision for
metabolic bone disease in kidney transplant recipients.
Funding: This study did not receive any specific grants from
any funding agencies in the public, commercial, or not-for-profit
sector.
Conflict of interest: Dilek Gogas Yavuz, Kadriye Aydin, Tugce
Apaydın, Arzu Velioglu, Meral Mert, Zafer Pekkolay, Ergun Parmaksiz,
Meral Mese, Ayse Esen Pazir, Emre Aydın, Onur Bugdayci, Serhan Tuglular
declare that they have no conflict of interest.