1. Petranova T1, Boyanov M2, Shinkov A3, Petkova R4, Psachoulia E5
Medication-taking behaviour in women with postmenopausal osteoporosis (OP) treated with denosumab or monthly oral bisphosphonates (oBPs)
Petranova T1, Boyanov M2, Shinkov A3, Petkova R4, Psachoulia E5
1Clinic of Rheumatology, Medical University, Sofia, Bulgaria; 2University Hospital Alexandrovska, Sofia, Bulgaria; 3University Hospital of Endocrinology "Acad. Iv. Penchev", Sofia, Bulgaria; 4Amgen Bulgaria, Sofia, Bulgaria; 5Amgen (Europe) GmbH, Zug, Switzerland
INTRODUCTION
Osteoporosis is characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to an increase in bone fragility and the risk of fractures.
In Bulgaria, post-menopausal osteoporosis treatment is initiated only by specialists (such as endocrinologists and rheumatologists). In the case of oral BPs, patients are subsequently followed by general practitioners (GPs), on a monthly basis. However, in the case of denosumab, patients return to the specialist to receive their injections on a 6-monthly base.
There are several therapies available for the prevention and treatment of osteoporosis, however , low persistence with many prescribed medication regimens is important factor in treatment failure.
The objective of the study was to describe treatment discontinuation among postmenopausal women initiating denosumab or monthly oBPs in routine clinical practice in Bulgaria.
METHODS
This retrospective chart review included postmenopausal women ≥50 years old initiating denosumab or monthly oBPs between 1-Oct-2011 and 30-Sep-2012, followed up to 24 months after treatment initiation.
Medical records of postmenopausal women initiating denosumab or monthly oBPs for OP were reviewed from 12 endocrinology or rheumatology practices scattered geographically across Bulgaria.
For both denosumab and monthly oBPs, discontinuation date was taken from the patients’ medical records (including any switch to another treatment/dosing regimen). If no such date was recorded, patients’ were assumed to have continued on treatment.
Denosumab persistence at 12, 18 and 24 months was defined as receiving the subsequent injection 6 months +60-days permissible gap after the previous injection; sensitivity analysis perfomed with 30 & 90 days permissible gaps. Persistence to monthly oBPs could not be calculated.
Descriptive statistics were conducted. Continuous variables were summarised as means ± SD (standard deviation). For categorical variables, the number and percentage of patients in each category were summarised.
RESULTS
Patient characteristics
Treatment discontinuation
A total of 224 women initiating denosumab and 217 initiating monthly oBPs met the inclusion criteria.
The characteristics of these women and their mean BMD T-score values at treatment initiation are described in Table 1 and Table 2.
Within the 24-month follow-up, 10 (4.5%) women initiating denosumab and 122 (56.2%) initiating monthly oBPs discontinued treatment; median (interquartile range) time to discontinuation in Table 3.
Table 3. Time to treatment discontinuation
Table 1. Patient characteristics at treatment initiation
No. of patients (%)
Median (days)
Q1 (days)
Q3 (days)
Denosumab
10 (4.5)
729
728.3
729.0
Monthly oBPs
122 (56.2)
367
354.0
484.8
Denosumab
(N=224)
Monthly oBPs
(N=217)
Age at treatment initiation (yrs), mean (SD)
63.4 (7.74)
64.4 (8.27)
Age at menopause (yrs), mean (SD)
47.8 (4.36)
48.9 (3.65)
Previous OP therapy, n (%)
Yes
44 (19.6)
26 (12.0) No
180 (80.4)
191 (88.0)
Previous fracture, n (%)
Yes‡
57 (25.5)
38 (17.5)
Yes, 1 fracture‡
56 (25.0)
Yes, 2 fractures‡
1 (0.4)
0 (0)
Location of previous fracture†, n (%)
Vertebral
42 (72.4)
31 (81.6)
Other
9 (15.5)
7 (18.4)
Hip
7 (12.1)
Out of the 10 women, who discontinued denosumab treatment, 2 (20%) was due to financial reasons & 8 (80%) for unknown reasons.
Out of the 122 women, who discontinued monthly oBPs treatment, the most common reasons were: 42 (34.4%) due to poor adherence, 23 (18.9%) for financial reasons, 19 (15.6%) due to lack of effect, 13 (10.7%) due to adverse events & 22 (18.0%) for unknown reasons.
43 women initiated denosumab treatment after discontinuation of their monthly oBP treatment initiated.
Denosumab persistence
Denosumab persistence (using 60 days permissible gap) was 100%, 99.1% and 98.7% at 12, 18 and 24 months, respectively.
Sensitivity analysis using 30 and 90 days permissible gap showed the same results.
OP, osteoporosis. ‡categories not mutually exclusive. †58 observations for denosumab & 38 for oBPs.
CONCLUSIONS
During the follow-up period, 3 (1.3%) women initiating denosumab and 8 (3.7%) initiating monthly oBPs experienced ≥1 OP fracture.
In this study of routine clinical practice in Bulgaria, only 4.5% of women initiating denosumab discontinued treatment within 24 months, compared to 56.2% of those initiating monthly oBPs.
At 12 & 24 months, denosumab persistence (60 days permissible gap) was high at 100% & 98.7% respectively.
Table 2. BMD T-scores at treatment initiation
Site
Denosumab
Monthly oBPs
No. of patients
Mean
Standard deviation
Lumbar spine
194
-3.20
±0.65
185
-2.95
±0.57
Total hip 12
-3.23
±0.69 23
-2.83
±0.73
Femoral neck 75
-2.61
±0.71 71
-2.42
±0.77
DISCLOSURE
This study was sponsored by Amgen (Europe) GmbH.
R. Petkova & E. Psachoulia are employees & shareholders of Amgen.
T. Petranova, M. Boyanov and A. Shinkov have received consulting, research and speaker fees and grants from many companies with drugs for bone diseases, including Amgen.