OrrWalker B, Wattie DJ, Evans MC, et al. Effects of prolonged bisphosphonate therapy and its discontinuation on bone mineral density in post-menopausal osteoporosis. Clinical Endocrinology 1997;46:87-92.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed/9059563
Reid IR, Wattie DJ, Evans MC, et al. Continuous therapy with pamidronate, a potent bisphosphonate, in postmenopausal osteoporosis. Journal of Clinical Endocrinology and Metabolism 1994;79:1595–99-95–99.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed/7989461
| Methods | Study design: Before-and-after study as a follow-up to a randomized controlled study
Number of groups: One group |
| Participants | Number of participants: 22 enrolled, 16 completed
Age: 65.9 ± 6.5 years Sex: 22 female, 0 male Participants with dementia: No Inclusion criteria: · Post-menopausal women · At least one vertebral fracture Exclusion criteria: · Disorders of calcium metabolism · Renal, thyroid, or hepatic dysfunction · Other major systemic disease; current use of anticonvulsant or glucocorticoid drugs · Past use of hormone replacement therapy · Treatment within the last 6 months with sodium fluoride, calcitonin, anabolic steroids or bisphosphonate Concurrent medicines: All subjects took the equivalent of 1 gram of elemental calcium at night for the entire 4 years of the study Country: New Zealand Setting: Community |
| Interventions | Medicine: Pamidronate 150mg daily
Withdrawal schedule: Not described |
| Outcomes | Change in Bone Mass Density |
| Dates | Dates: Not described
Follow-up duration: Four years total – Three years pamidronate treatment, one year deprescribing |
| Funding sources | Health Research Council of New Zealand, Ciba-Geigy (NZ) Ltd, The Arthritis Foundations of New Zealand, ASB Charitable Trust, Paykel Trust and the New Zealand Lottery Grants Board |
| Notes |
Risk of bias table
| Bias | Authors’ judgment | Support for judgment |
| Random sequence generation (selection bias) | High risk | The women participating were randomized for the original study. This study includes only the women who were randomized to active treatment in the original study. |
| Allocation concealment (selection bias) | High risk | It was an open study. |
| Blinding of participants and personnel (performance bias) | 5 out of 5 | It was an open study. |
| Blinding of outcome assessment (detection bias) | 5 out of 5 | As above. |
| Incomplete outcome data (attrition bias) | 5 out of 5 |
The analysis was as-treated. |
| Selective reporting (reporting bias) | 3 out of 5 | There was a pre-specified protocol for the original study, but this study appears to have been considered afterwards. It is unclear that there was a pre-specified analysis plan. This appears to be an “opportunistic” study following from a strong randomized controlled trial. The outcome measure was simple and fully reported. |
| Confounding (non-randomized) | 5 out of 5 | The authors did not continue to track those women who had originally been randomized to the placebo group, which would have provided a control group, nor did they randomize women to continue/discontinue therapy. Instead, this is a single-arm study.
Few confounders were considered. No account of other medications was taken e.g. vitamin D, Calcium, proton pump inhibitor, hormonal status |
| Other bias | Low risk | |
| Newcastle-Ottawa scale | ||
| Selection bias | Representativeness of the exposed cohort | The intervention cohort was a selected group of users. |
| Selection of the non-exposed cohort | There was no concurrent control group.
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| Ascertainment of exposure | Ascertainment of exposure: secure record
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| Demonstration that outcome of interest was not present at start of study | Demonstrated that outcome of interest was not present at start of study. | |
| Comparability bias | Comparability of cohorts on the basis of the design or analysis | The study controlled for bisphosphonate cessation. |
| Outcome bias | Assessment of outcome | Assessment of outcome: record linkage |
| Was follow-up long enough for outcomes to occur | Follow-up was long enough for outcomes to occur
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| Adequacy of follow-up of cohorts | Inadequate of follow-up of cohorts: follow-up rate of 27% lost | |
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