Key words glucocorticoid-induced osteoporosis - bisphosphonate - teriparatide - bone mineral
density - bone fracture
Introduction
Osteoporosis (OP) is characterized as decreased bone mineral density (BMD) and
deteriorated micro-architecture, resulting in increased risk of bone fracture [1 ]. Osteoporosis results in 1.5 million
fractures per year in the United States, leading to poor quality of life and
increased mortality risk [2 ]. Most of them are
menopausal or age-dependent osteoporosis. However, secondary osteoporosis due to
hypercortisolism, hyperparathyroidism, rheumatic disorders, malnutrition, diabetes
mellitus, and multiple myeloma also account for a certain proportion. The
persistently excess glucocorticoid, including both endogenous hypercortisolism such
as Cushing’s syndrome and the exogenous steroid medicine intake, leads to
glucocorticoid-induced osteoporosis (GIOP). The clinical characteristic of GIOP is
rapidly decreased BMD, and increased bone fracture risk [3 ].
The anti-osteoporosis intervention for GIOP is based on the fracture risk.
Computer-based fracture risk-assessment tool (FRAX) provides the probability of bone
fracture for individuals using glucocorticoid. The anti-osteoporosis agents are
classified into anti-resorptive agents, and anabolic agents and those affect both
bone formation and resorption. Current therapeutic strategies for GIOP are similar
to menopausal osteoporosis, including bisphosphonates, parathyroid hormone (PTH)
analogues {recombinant human parathyroid hormone [rhPTH(1–34),
teriparatide]}, a monoclonal antibody of RANKL (Denosumab), and selective estrogen
receptor modulators (SERMs). Bisphosphonates, the classic anti-resorptive agents,
are considered as the most common therapeutic option for GIOP [4 ]. A Cochrane review involving 12 RCTs and
1343 participants suggested that bisphosphonates had a 43% lower risk of new
vertebral fractures than calcium and vitamin D supplementation [5 ]. Teriparatide and abaloparatide (the
analogous of PTH receptor) are anabolic agents to promote bone formation. PTH
stimulates Wnt/beta-catenin signaling pathway, increases osteoblast
differentiation and maturation, enhances BMD, and reduces bone fracture risk [6 ]. According to the pathophysiology of GIOP
and mechanism of bisphosphonate and teriparatide action, they could be considered
as
effective therapeutic strategy for GIOP patients with high fracture risk.
Previously, several published meta-analyses compared anti-osteoporotic agents,
nevertheless, some disadvantages existed in those studies [7 ]
[8 ]
[9 ]
[10 ]. Most of them studied on primary OP, mainly
due to menopausal osteoporosis and aging. However, the physiopathologic mechanism
of
GIOP differs from primary OP, the former occurs due to the persistent excessive
glucocorticoid. In this study, we focused on the comparison between bisphosphonate
and teriparatide on the efficiency and safety and discuss the possible affecting
factors of BMD and fracture rate, to help make decisions on pharmacotherapy for GIOP
patients.
Materials and Methods
Search strategy
We performed this systematic review and meta-analysis based on the prespecified
protocol and report our methods and results in accordance with the Preferred
Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines
[11 ].
We searched databases including PubMed, Embase, and the Cochrane Library until
January 1st, 2023, to identify random clinical trials (RCT)s that reported the
efficacy and/or safety of bisphosphonate vs teriparatide therapy for
GIOP patients. Two reviewers (Dong B and Zhou Y) independently screened titles
and abstracts of all records and full texts of potentially eligible studies. We
searched using medical subject heading (MeSH) associated with terms relevant to
“glucocorticoid-induced osteoporosis”, “steroid-induced
osteoporosis”, “bisphosphonate”,
“teriparatide” together with “randomized controlled
trial”. Any disagreements were resolved by consensus with a third
reviewer (Wang J).
Study inclusion and exclusion criteria
Studies included in this meta-analysis were required to meet the following
inclusion criteria: (1) study design: RCT of GIOP with a comparison between
bisphoshonate and teriparatide with a duration of at least 18 months; (2) study
subjects: adult patients diagnosed with osteoporosis
(T-score<–2.5) or osteopenia (T-score between –1.0 and
–2.5) with or without prior fracture. Subjects also had received GC
therapy at a dose of>5 mg/day prednisone or its
equivalent for at least three months; (3) study intervention: subjects received
teriparatide 20 μg/d subcutaneously, or bisphosphonate
treatment including oral aldendronate 10 mg/d or risedronate
35 mg/week for at least 18 months; and (4) the change of BMD
could be measured by dual-energy X-ray absorptiometry (DXA) at the lumbar spine,
total hip, or femoral neck. Trials were excluded if (1) malignant tumor exists
with bone metastasis, metabolic osteopathy, or primary osteoporosis patients;
(2) the same RCT was re-analyzed; (3) BMD were not evaluated by DXA; and (4)
studies published as abstracts, reviews, editorials, and letters without
available full texts.
Data collection process and quality assessment
Two independent reviewers (Dong B and Zhou Y) extracted data from the eligible
studies, using predefined forms containing information on trial characteristics
(first author, publication year, sample size, dose and varieties of agents, and
treatment duration), participants’ baseline characteristics (age,
gender, menopause state, previous fracture, base anti-osteoporotic treatment),
and outcomes of interest mentioned above. Any resulting disagreements were
judged by discussion with a third author (Wang J).
The quality of the involved study was assessed using the Cochrane
Collaboration’s risk-of-bias assessment tool, which included random
sequence generation (selection bias), allocation concealment (selection bias),
blinding of participants, and personal (performance bias), blinding of outcome
assessment (detection bias), incomplete outcome data (attrition bias), selective
reporting (reporting bias), and other potential sources of bias. The judgment
for each entry involves answering a question, with low risk of bias, high risk
of bias, and unclear indicating lack of information or uncertainty about the
possibility of bias. Disagreements between authors were resolved with
consensus.
Outcomes of measurements
The primary outcomes were the mean changes of BMD percentage from baseline at the
lumbar spine, total hip, and femoral neck at 18 months. The secondary outcomes
included: (1) overall incidence of vertebral and non-vertebral fractures; (2)
the percentage changes of bone formation marker propeptide of type I procollagen
(PINP) and bone resorption marker C-terminal telopeptide (beta-CTX) at 6 and 18
months; and (3) adverse events (Aes), severe adverse events (SAEs), and withdraw
due to intolerance to AEs were also compared.
Data synthesis and statistical analysis
For each outcome measure of interest, the mean difference (MD) and its
95% CI were applied for continuous variables (percentage changes of BMD
at lumbar spine, total hip and femoral neck), while risk ratio (RR) and its
95% CI were used for dichotomous outcomes (risk for fracture and adverse
events). Considering the differences in baseline participants’
characteristics and drug administration, a random effects model was selected for
analyses. A p-value<0.05 for any test or model was considered
statistically significant. The degree of between-study variability attributable
to heterogeneity beyond chance was calculated using the I2 statistic
and Q statistic. Outcomes with I2 levels from 0% to
40% were considered minimally heterogeneous, while I2
>50% was considered an indication of statistically significant
heterogeneity among included studies.
We conducted perspective meta-regression by study characteristics to address the
clinical heterogeneity of included studies. We analyzed factors including age,
sex, menopausal status, the ethnic difference (Caucasian percentage), previous
bisphosphonate usage, steroid dosage, steroid duration, underlying diseases,
previous vertebral or non-vertebral bone fracture, previous spinal or hip or
femoral BMD (T-score).
Risk of bias assessment were performed by the Review Manager statistical software
package (Version 5.3). The meta-analyses and regression-analyses were performed
by the STATA statistical software package (Version 12.0).
Results
Search results
A total of 130 studies were screened from the Pubmed, EMBASE, and Cochrane
databases. After reviewing the titles and abstracts, 98 were reviews or not
relevant studies. Five duplicates were removed, and 6 articles were not RCTs.
Three articles were excluded because the type or the duration of medication were
not meeting the requirements. Five other articles were excluded because of the
inclusion criteria, not comparing the efficiency of bisphosphonate and
teriparatide, one article was excluded for not elevating the BMD or bone
fracture, one for re-analysis of the same trial, and one article was published
in abstract form. Ten RCTs [12 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ]
[18 ]
[19 ]
[20 ]
[21 ] were finally involved
in this meta-analysis ([Fig. 1 ]).
Fig. 1 Flow diagram of study selection.
Characteristics of the included trials
A total of 1960 subjects with GIOP received >5 mg equivalent PSL
for at least 3 months, including postmenopausal, premenopausal women, and men in
this meta-analysis. Those studies were intervened with bisphosphonate (eight
studies with alendronate and two studies with risedronate) or teriparatide for
at least 18 months, evaluated lumbar spinal, total hip and femoral neck BMD,
vertebral and non-vertebral bone fracture incidence, bone formation marker and
bone resorption marker, and adverse effects.
The mean age range was from 55.4–58.4 years old, 80% of the
subjects were women, 72.3% were menopause women with osteoporosis, and
two studies involved only men. The underlying disorders requiring glucocorticoid
treatment included rheumatic disorders (rheumatoid arthritis, systemic lupus
erythematosus, polymyalgia rheumatic, vasculitis), respiratory disorders, and
inflammatory bowel diseases. The mean glucocorticoid dose ranged from
7.5–10 mg/d equivalent PSL, and the mean usage duration ranged
from 1.3–6.4 years. A sum of 41.92% of patients had previous
bone fractures, and 12.1% had prior anti-osteoporosis therapy with
bisphosphonates. All patients received daily 1000 mg calcium and
800–1000 IU vitamin D supplement.
Risk of bias assessment
The risk of bias was assessed with the Cochrane risk-of-bias tool. There was a
low risk of reporting bias in all the trials except for one study that had an
unclear risk of selective reporting ([Fig.
2 ]). Two studies had a relatively small sample size and only men
participated in the studies (Gluer 2013 [20 ] and Farahmand 2013 [19 ]).
In addition, these two studies used an open-label RCT design.
Fig. 2 Quality assessment of the studies.
Change in BMD
The primary outcome analysis evaluated the change of BMD from baseline intervened
by bisphosphonates or teriparatide for 18 months, involving six trials with a
total of 1694 patients. Compared to bisphosphonates, the teriparatide therapy
increased lumber spinal BMD by 3.96% (95% CI
3.01–4.9%, p<0.00001). The increase of BMD used
teriparatide was greater by 1.23% (95% CI
0.36–2.1%, p=0.006) at total hip, and 1.45%
(95% CI 0.31–2.58%, p=0.01) at femoral neck,
respectively ([Fig. 3 ]). These results
showed that teriparatide increased greater BMD than bisphosphonate at all three
positions. The extent of BMD increase by bisphosphonate or teriparatide differs
from different positions.
Fig. 3 Subgroup analysis of the efficiency of BMD change
(%) by bisphosphonate and teriparatide for GIOP at lumbar spine
(a ), total hip (b ), and femoral neck (c ).
One trial (Saag 2009 [13 ]) prolonged
continuation of the observational phase for another 18 months. At a total of 36
months, teriparatide group showed even greater mean increase of BMD from
baseline than alendronate at the lumbar spine (ALN 5.3% vs. TPTD
11.0%, p<0.001), at total hip (ALN 2.7% vs. TPTD
5.2%, p<0.001), and at femoral neck (ALN 3.4% vs. TPTD
6.3%, p<0.001), respectively [13 ]. The increasing extent at 36 months was significantly greater
compared with that measured at 18-month time point. Thus, long-term treatment
with teriparatide on GIOP may bring a more significant effect of increasing BMD
showing a time-dependent tendency, and the extent of BMD enhancement was
enlarged in the bisphosphonate therapy.
Bone fracture risk
Three trials involved 1099 patients who reported the efficacy of bisphosphonate
or teriparatide on vertebral bone fracture and 1191 patients on non-vertebral
fracture during the observation phase. Teriparatide group showed significantly
reduced incidence of vertebral bone fracture than bisphosphonates
(p=0.0001, RR 6.27, 95% CI 2.44–16.07). However,
teriparatide therapy showed no significant difference in reducing the risk of
non-vertebral bone fracture (p=0.93, RR 0.98, 95% CI
0.62–1.55) ([Fig. 4 ]). The effect
on reducing bone fracture incidence differed from different positions.
Teriparatide exhibited better performance than bisphosphonate in decreasing the
risk of vertebral bone fracture, but not non-vertebral bones.
Fig. 4 Forest plot of the bone fracture risk by bisphosphonate and
teriparatide treatment at vertebral (a ) and non-vertebral
(b ) fracture at 18 months.
Bone biomarkers bone formation markers and bone resorption markers
Five studies elevated bone turnover markers including bone formation marker PINP
and bone resorption marker beta-CTX at 6-month and 18-month. Teriparatide
therapy showed significantly increase in bone formation biomarker PINP changes
from baseline (Supplemental Fig. 1S ), as well as the bone resorption
marker CTX (Supplemental Fig. 2S ). In contrast, according to the
mechanism of bisphosphonate, it showed reduced bone formation and bone
resorption marker, suggesting its inhibitory effect on bone remodeling.
Adverse effects
Three studies reported adverse events and severe adverse events. Bisphosphonate
did not show significant difference from teriparatide on the incidence of
adverse effects (RR –0.01, 95% CI –0.1–0.08,
p=0.77) or severe adverse effects (RR 1.27, 95% CI
0.53–3.03, p=0.59) reports ([Fig. 5 ]). However, three trials in total of 411 patients provided
data showed that the risk of withdraw due to AE was increased in the
teriparatide group (RR 0.57, 95% CI 0.33–1.00, p=0.05)
([Fig. 5 ]), with mild moderate
heterogeneity (I2 =38%). The common adverse events
include peripheral edema, influenza, nausea, arthralgia, fall, or even
death.
Fig. 5 Forest plot of adverse events at 18 months. Risk ratio of
adverse events (a ), severe adverse events (b ), and
withdraw due to adverse events (c ).
Publication bias
The publication bias of the primary outcomes of BMD at the spinal, total hip, and
femoral neck was judged using funnel plots (Supplemental Fig. 3S ) and
Egger’s weighted regression statistic. The publication bias of vertebral
and non-vertebral bone fracture was judged using funnel plots (Supplemental
Fig. 4S ). The mean difference of BMD change from baseline at the lumbar
spine, total hip, and femoral neck using Egger’s test were
p=0.792, 0.137, 0.33, respectively. There was no significant publication
bias.
Meta-regression analysis
Meta-regression analysis showed that factors including age, sex, menopausal
status, steroid dosage, steroid duration, underlying diseases and previous
rheumatic diseases, and previous bone fracture are not associated with the
incidence of vertebral bone fracture ([Table
1 ]), neither with the increasing extent of BMD at the lumbar spine,
total hip and femoral neck (data not shown), using bisphosphonate or
teriparatide.
Table 1 Meta-regression analysis of the demographic and
clinical variables concerning the risk of vertebral bone fracture in
GIOP.
Characteristics
Coefficient, 95% CI
p-Value
Tau2
Adj R-squared (%)
Age
1.395 (0.146–13.361)
0.671
1.436
−18.69
Female (%)
2.349 (0.062–88.767)
0.509
1.267
−4.74
Menopausal female
1.089 (0.658–1.803)
0.541
1.483
−11.24
Steroid dosage
2.356 (0.524–10.595)
0.167
0.599
50.42
Steroid duration
1.582 (0.472–5.299)
0.314
0.944
21.98
Underlying disease (previous rheumatic disease)
0.387 (0.00–25.483)
0.433
1.24
6.79
Previous fracture
1.342 (0.235–7.664)
0.543
1.487
−11.55
Previous vertebral fracture
1.348 (0.197–9.208)
0.655
1.431
−18.27
All are univariate meta-regression analyses, with the exception of
teriparatide compared with bisphosphonate as a reference. Proportion
between study variance was explained with Hartung–Knapp
modification.
Discussion
In this meta-analysis of RCTs, we compared the efficiency and safety of
bisphosphonates and teriparitide on GIOP. We investigated the primary outcome of the
BMD change from baseline at 18 months’ therapeutic duration. We also
compared the bone fracture risk of vertebral and non-vertebral bone, the change of
bone formation marker PINP and bone resorption marker b-CTX, and the incidence of
adverse events. Our study provided evidence that teriparatide is more effective than
bisphosphonate in increasing BMD at the lumbar spine, total hip, and femoral neck
at
18 months, especially in enhancing spinal BMD. In addition, bone fracture risk was
reduced in the teriparatide treatment group on vertebral bone but not non-vertebral
bone. Teriparatide significantly increased PINP and b-CTX level, however, based on
the acting mechanism, bisphosphonate reduced bone turnover. The incidence of adverse
events did not show a difference between two groups. Meta-regression analysis showed
that factors including age, gender, menopausal status, ethnic difference, previous
bisphosphonate usage, steroid dosage and duration, underlying disease and previous
rheumatic disease, and previous fracture, previous BMD are not associated with the
increasing extent of BMD, neither the incidence of vertebral or non-vertebral bone
fracture.
Persistent glucocorticoid usage disturbs bone metabolism. Glucocorticoids directly
inhibit osteoblasts proliferation and differentiation by activating caspase 3,
triggering the expression of Wnt signaling inhibitors sclerostin and dickkopf-1, and
suppressing Wnt signaling to downregulate the expression of key osteogenic
transcriptional factor Runx2, AP-1, and osteocalcin [22 ]. On the contrary, glucocorticoids increase receptor activator of
nuclear factor-κB ligand (RANKL) and reduce osteoprotegerin (OPG) expression
to imbalance the OPG/RANKL ratio, promote the maturation and function of
osteoclasts, and transiently increase bone resorption [23 ]. Glucocorticoids also increase osteoblasts
and osteocytes apoptosis [24 ]. Thus, the usage
of glucocorticoids suppresses bone formation and enhances osteoclast-induced bone
resorption. In addition, glucocorticoids suppress calcium absorption through
intestine, increase renal calcium excretion, accelerate muscle wasting, and reduce
sex-steroids [25 ]. Those mechanisms aggravate
the decrease bone mass and bone strength. Moreover, the underlying conditions
required glucocorticoid usage, such as rheumatoid arthritis, ankylosing spondylitis,
inflammatory bowel disease, already have existed bone metabolic disorders [26 ]
[27 ].
For the treatment of GIOP, bisphosphonates inhibit bone resorption and remodeling;
they are recommended as first-line agents to prevent glucocorticoid-induced
fractures [4 ]
[28 ]. Randomized trials and clinical experience showed that bisphosphonate
are generally safe and well tolerated. However, besides mild hypocalcemia, other
severe rare adverse effects including osteonecrosis of the jaw and atypical femoral
fractures have been observed [29 ]
[30 ].
Teriparatide is an anabolic agent that mainly increase bone formation. The anabolic
mechanism of PTH analogues relays on the rapid, transitory, and short-acting pulse.
Therefore, teriparatide is administered by daily injection and is approved for up
to
two years of use. After the administration is discontinued, its benefits are quickly
lost, so it should be followed by an antiresorptive agent [31 ]. In vitro study, PTH stimulates
Wnt/beta-catenin signaling, upregulates the expression of key osteogenic
factors including Osteocalcin, Runx2, promotes osteoblast differentiation and bone
formation [32 ]. Those mechanisms directly
inhibit glucocorticoid induced bone loss. However, the BMD cannot maintain and
fracture risk increase after teriparatide is discontinued. Therefore,
anti-resorptive agents such as bisphosphonate or denosumab are recommended to use
after teriparatide administration.
Risk factors for glucocorticoid-induced bone fractures include age (>55
years), female sex, white race, menopause, previous fracture, and long-term use of
daily doses of >7.5 mg equivalent prednisolone [4 ]. Cumulative glucocorticoid dose is an
important factor that correlates with BMD reduction and fracture risk [33 ]
[34 ].
Factors such as age, sex, body mass index (BMI), menopausal status, fracture
history, exercise, smoking, alcohol consumption should be considered as the bone
fracture risk, but have no direct correlation according to the study of Van Staa et
al. [35 ]. According to our investigation on
meta-regression comparing the efficiency of bisphosphonate and teriparatide, those
factors including age, gender, menopausal status, ethnic difference, previous
bisphosphonate usage, steroid dosage, steroid duration, underlying diseases,
previous vertebral or non-vertebral bone fracture, previous BMD are not associated
with the change of BMD, neither the incidence of vertebral or non-vertebral bone
fracture using both bisphosphonate and teriparatide. Considering fracture risk
increases with aging and dose-dependency of glucocorticoid usage, early prevention
is important.
Findings
We performed the meta-analysis of ten RCTs, involving a total of 1960 GIOP patients,
compared the effect of bisphosphonate and teriparatide on enhancing BMD at the
spinal, total hip, and formal neck, decreasing bone fracture, the adverse effects,
and tolerance. Compared to bisphosphonate, teriparatide treatment for GIOP showed
greater BMD change from baseline on vertebral spine, total hip, and femoral neck.
Teriparatide exhibited a greater increasing extent on spinal BMD than other parts,
suggesting the enhancement of BMD differ from different positions. In addition, the
bone fracture incidence was lower in teriparatide treatment in the 18-month phase.
Teriparatide also improved bone turnover by increasing bone formation maker PINP and
bone resorption marker beta-CTX. On the contrary, bisphosphonate, based on its
mechanism of action, reduced bone metabolic markers and suppressed bone turnover.
Both of the agents showed good performance on safety, however, the incidence of
adverse events leading to withdraw was increased in the teriparatide group. In
addition, factors such as age, female, menopausal status, steroid dosage and
duration, previous bone fracture are not associated with the efficiency and fracture
risk in neither bisphosphonate nor teriparatide therapy.
Comparison with previous studies
Other meta-analyses have reported the comparison between bisphosphonate and
teriparatide to treat osteoporosis [10 ]
[36 ]. However, most of those
reports are primary osteoporosis, including aging and menopausal associated
osteoporosis, but not particularly in GIOP. According to the different
mechanism, the anabolic agent teriparatide showed better performance in GIOP.
Compared to the previous studies, we investigated the increasing extent of BMD
and reducing fracture risk in different positions, and discussed the change of
bone formation and resorption markers. These results may help advance the
therapeutic strategy for osteoporosis induced by steroid.
Limitations
This study has limitations. 1) The number of involved RCTs and participants was
small. It might result in the risk of bias in reporting and limit a quantitative
analysis of the publication bias. 2) Due to the small number of studies and
involved patients, there was limited ability to perform subgroup analysis. 3)
Most of the included RCTs had the phase of 18 months, lacked the long-term
observation.
Conclusions
Teriparatide significantly increased BMD at the lumber spine, total hip, and femoral
neck than bisphosphonate with 18-month therapy for GIOP. Teriparatide also reduced
bone fracture especially in vertebral bone, and improved bone remodeling by
increasing bone formation and resorption marker levels. Teriparatide showed better
performance over bisphosphonate in BMD enhancement, bone fracture reduction and bone
remodeling improvement, without increasing the incidence of adverse effects.