Research shows romosozumab, a bone-strengthening injection, works equally well in patients 85 years and older as in younger adults, increasing bone density by about 11% in both groups over 12 months. According to Gram Research analysis of 417 patients in Japan, very elderly patients should not be excluded from this treatment based on age alone, as they showed the same bone-building response as younger patients despite having the highest fracture risk
A Gram Research analysis of 417 patients in Japan found that romosozumab, a bone-strengthening injection, works equally well for people over 85 years old as it does for younger adults. The drug increased bone density by about 11% in both age groups over 12 months. This is important because very elderly people have the highest risk of broken bones, yet they’re often left out of drug studies. The research shows doctors shouldn’t avoid giving this treatment to older patients just because of their age.
Key Statistics
A 2026 multi-center cohort study of 417 patients in Japan found that romosozumab increased spine bone density by 11.1% in patients under 85 years and 10.9% in patients 85 years and older over 12 months, demonstrating statistically equivalent responses between age groups.
In the same study of 417 patients, bone turnover markers decreased similarly in both age groups: P1NP dropped 16.4% in younger patients versus 19.6% in very elderly patients, and TRACP-5b fell 32.1% versus 33.1% respectively, indicating the drug works through identical biological mechanisms across ages.
Among 417 Japanese patients receiving romosozumab, fragility fracture rates during 12 months of treatment were 5.2% in patients under 85 years and 7.0% in patients 85 years and older, with no statistically significant difference between groups.
A 2026 real-world cohort study of 417 patients found that prior bone treatment attenuated romosozumab response in younger patients (7.5% improvement if pretreated versus 14.6% if treatment-naive) but had no effect in patients 85 and older (10.7% versus 11.2%), suggesting different treatment response patterns in very elderly patients.
The Quick Take
- What they studied: Whether a bone-strengthening drug called romosozumab works the same way in very elderly patients (85 and older) as it does in younger adults
- Who participated: 417 patients from two hospitals in Japan who started taking romosozumab between 2019 and 2025. About 71 patients were 85 or older, and 346 were younger than 85
- Key finding: Both age groups had nearly identical bone density improvements after 12 months: 11.1% in younger patients and 10.9% in very elderly patients. The difference was so small it proved the drug works equally well in both groups
- What it means for you: If you’re over 85 and have weak bones, romosozumab may be just as effective for you as for younger people. However, talk with your doctor about whether this treatment is right for your specific health situation
The Research Details
Researchers looked back at medical records from two hospitals in northern Japan to see how well romosozumab worked in different age groups. They tracked 417 patients who received monthly injections of the drug starting between April 2019 and April 2025. The main measurement was how much bone density improved in the spine after 12 months of treatment.
To prove the drug worked equally well in both age groups, researchers used a special statistical test called equivalence testing. Instead of just looking at whether results were similar, they checked whether the differences fell within acceptable ranges (within 3 to 5 percentage points). This is a more rigorous way to prove two treatments work the same way.
The study also measured bone turnover markers, which are chemicals in the blood that show how active bone remodeling is happening. Researchers compared these markers between age groups and looked at whether taking vitamin D alongside romosozumab changed the results.
Very elderly people (85 and older) have the highest risk of broken bones and fractures, yet they’re almost never included in the big clinical trials that test new drugs. This real-world study fills that gap by showing what actually happens when very elderly patients take romosozumab in regular medical practice, not just in controlled research settings
This study has several strengths: it included a decent-sized group of very elderly patients (71 people over 85), it tracked them for a full year, and it measured multiple markers of bone health. The study was conducted at two real hospitals using actual patient records, which makes the results more applicable to everyday medical practice. However, the study looked backward at existing records rather than randomly assigning patients to treatment groups, which is less powerful than a randomized trial. The study was also limited to patients in Japan, so results might differ in other populations
What the Results Show
The main finding was striking in its simplicity: romosozumab worked almost identically in very elderly patients and younger adults. Patients under 85 years old had a median spine bone density increase of 11.1% after 12 months, while those 85 and older had an increase of 10.9%. This tiny 0.2% difference was so small that statistical tests confirmed the two groups had truly equivalent responses to the drug.
The researchers used two different statistical tests with different acceptable ranges to prove equivalence. The drug passed both tests, meaning the results were robust and not dependent on which statistical method was chosen. Hip bone density also showed equivalent improvements between age groups.
Bone turnover markers, which measure how actively bones are being remodeled, decreased similarly in both groups. In younger patients, one marker (P1NP) dropped 16.4%, while in very elderly patients it dropped 19.6%. Another marker (TRACP-5b) fell 32.1% in younger patients and 33.1% in very elderly patients. These similar decreases suggest the drug is working through the same biological mechanisms in both age groups.
An interesting pattern emerged when researchers looked at patients who had received other bone treatments before starting romosozumab. In younger patients, those who had prior treatment showed a smaller bone density improvement (7.5%) compared to treatment-naive patients (14.6%). However, this pattern did not appear in very elderly patients, who showed similar improvements whether or not they had prior treatment (10.7% vs. 11.2%). This suggests the very elderly may respond differently to previous bone therapies, though the researchers note this finding needs further investigation.
About half of patients in each age group (50.6% in younger patients and 53.5% in very elderly patients) were also taking vitamin D supplements. The presence or absence of vitamin D did not change how well romosozumab worked in either age group, suggesting the drug’s benefits are independent of vitamin D status.
Fracture rates during the 12-month treatment period were low in both groups and not significantly different: 5.2% in younger patients and 7.0% in very elderly patients. Kidney function and calcium levels remained similar between groups throughout the study.
Previous large clinical trials of romosozumab included very few patients over 85 years old, leaving a major gap in our knowledge about how the drug works in the oldest patients. This real-world study directly addresses that gap by showing that the drug’s effectiveness doesn’t diminish with age. The bone density improvements observed here (around 11% in both groups) are consistent with what was seen in the original clinical trials, but now we have proof it applies to very elderly patients too
This study looked backward at existing medical records rather than randomly assigning patients to treatment and control groups, which is less powerful for proving cause and effect. The study was conducted only in Japan, so results might not apply equally to other populations with different genetics or healthcare practices. The study didn’t include a control group of very elderly patients who didn’t receive romosozumab, so we can’t directly compare treated versus untreated patients in this age group. Some patients were lost to follow-up or didn’t have complete bone density measurements at 12 months, which reduced the final sample size slightly. The study measured bone density but not actual fracture prevention over longer time periods, though fracture rates during the study were tracked
The Bottom Line
Based on this research, romosozumab appears to be an effective treatment option for bone loss in patients 85 years and older, with strong evidence supporting its use in this age group. The drug should not be withheld from very elderly patients simply because of their age. However, treatment decisions should always be made in consultation with a healthcare provider who can evaluate individual health status, kidney function, calcium levels, and other medications. This evidence is particularly relevant for very elderly patients at high risk of fractures
This research is most relevant for very elderly adults (85 and older) with osteoporosis or bone loss, their family members, and healthcare providers treating older patients. It’s also important for people in their 60s and 70s who may eventually reach advanced age and want to know about treatment options. Policymakers and insurance companies should note that age alone should not be a barrier to receiving this treatment
Based on this study, you can expect to see measurable improvements in bone density within 12 months of starting romosozumab. The drug is given as a monthly injection, so consistent treatment over the full year is important. Benefits may continue beyond 12 months, though this study only tracked the first year. Actual fracture prevention may take longer to demonstrate and would require longer follow-up studies
Frequently Asked Questions
Does romosozumab work as well in people over 85 as in younger adults?
Yes. A 2026 study of 417 patients found romosozumab increased bone density by 11.1% in younger patients and 10.9% in those 85 and older, proving equivalent effectiveness. The drug works through the same biological mechanisms in both age groups.
Is romosozumab safe for very elderly patients with weak bones?
This study found romosozumab safe in patients 85 and older, with similar fracture rates (7.0%) and comparable kidney function and calcium levels as younger patients. However, individual safety depends on your specific health conditions, so consult your doctor.
How much does bone density improve with romosozumab in elderly patients?
In patients 85 and older, romosozumab increased spine bone density by a median of 10.9% over 12 months. Hip bone density also improved equivalently. These improvements were similar to those seen in younger patients receiving the same treatment.
Should doctors avoid giving romosozumab to patients over 85 just because of their age?
No. This research shows romosozumab should not be withheld from very elderly patients based on age alone, since they respond as well as younger patients. Treatment decisions should be based on individual health status, not age.
Does taking vitamin D with romosozumab change how well it works in elderly patients?
No. The study found that about half of patients in each age group took vitamin D, and it did not modify romosozumab’s bone density response in either younger or very elderly patients.
Want to Apply This Research?
- Track monthly romosozumab injection dates and any bone-related symptoms or falls. Set reminders for monthly injections and log any changes in mobility, pain levels, or balance issues to share with your healthcare provider
- Use the app to schedule monthly injection appointments and set reminders to take them on time. Log calcium and vitamin D intake daily, and track any physical activities that support bone health like weight-bearing exercise
- Record bone density test results when available (typically done yearly or every 2 years). Track fall incidents, fractures, or bone pain. Monitor kidney function and calcium levels through regular blood work, and log any side effects or concerns to discuss with your doctor at follow-up visits
This article summarizes research findings and should not be considered medical advice. Romosozumab is a prescription medication that requires a doctor’s evaluation and monitoring. Individual responses to treatment vary based on age, kidney function, calcium levels, other medications, and underlying health conditions. Very elderly patients considering romosozumab should discuss potential benefits and risks with their healthcare provider, including possible side effects and interactions with other treatments. This research was conducted in Japan and may not apply equally to all populations. Always consult with a qualified healthcare professional before starting, stopping, or changing any osteoporosis treatment.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.