Long-term follow-up study shows benefits lasted for years after randomized trial
Washington, DC–For years after it was administered, growth hormone continued to reduce the risk of fractures and helped maintain bone density in postmenopausal women who had osteoporosis, according to a new study published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism.
Osteoporosis is a progressive condition that causes the bones to become weak and more likely to break. More than 10 million American adults have osteoporosis, and 80 percent of the people being treated for the condition nationwide are women, according to the Society’s Endocrine Facts and Figures Report. Women are three times more likely to experience an osteoporosis-related bone fracture in their lifetimes than men.
“Our study is the largest and longest controlled study of growth hormone treatment for osteoporosis in postmenopausal women to date,” said one of the study’s authors, Emily Krantz, MD, of Södra Älvsborgs Hospital in Borås, Sweden. “Years after treatment stopped, women who were treated with growth hormone still experienced improved bone density and reduced fracture risk.”
During an 18-month-long randomized, double-blind trial, 80 postmenopausal women with osteoporosis received daily injections of either placebo, a single unit of growth hormone or a 2.5-unit dose of growth hormone. The women were between the ages of 50 and 70 when they were recruited for the decade-long study.
After 18 months, the women who received the placebo halted the injections. Women who received growth hormone continued to receive injections for another 18 months. The researchers continued to follow up with the women for seven years after the growth hormone treatment was halted to monitor their bone density, fractures and perception of their quality of life.
The researchers compared the participants’ bone density and rate of fractures to those of a group of 120 women who did not have osteoporosis. The controls were identified using the city census in Gothenburg, Sweden.
A decade after the study began, the women who received the larger growth hormone dose still had higher bone mineral density levels than the participants who received the lower dose or the placebo. The rate of fractures in the treated women who had osteoporosis declined by 50 percent during the 10-year-long study. More than half of the participants had fractured bones prior to the start of the study. In contrast, the rate of fractures rose four-fold in the control group as some of those women were diagnosed with osteoporosis.
“The findings indicate the beneficial effects of growth hormone remained long after the treatment ceased,” Krantz said.
Other authors of the study include: Penelope Trimpou and Kerstin Landin-Wilhelmsen of Sahlgrenska University Hospital at the University of Gothenburg in Gothenburg, Sweden.
The study, “Effect of Growth Hormone Treatment on Fractures and Quality of Life in Osteoporosis – A 10-year Follow-up,” was published online at http://press.endocrine.org/doi/10.1210/jc.2015-1757, ahead of print.
Founded in 1916, the Endocrine Society is the world’s oldest, largest and most active organization devoted to research on hormones and the clinical practice of endocrinology. Today, the Endocrine Society’s membership consists of over 18,000 scientists, physicians, educators, nurses and students in 122 countries. Society members represent all basic, applied and clinical interests in endocrinology. The Endocrine Society is based in Washington, DC. To learn more about the Society and the field of endocrinology, visit our site at http://www.endocrine.org. Follow us on Twitter at https://twitter.com/#!/EndoMedia.
This release focuses on a study that reports long-term benefits in regard to bone density and reduced risk of bone fractures for women with osteoporosis who take growth hormone. However, the release does not make sufficiently clear that this was a small-scale study nor does it mention any risks or side effects associated with the use of growth hormone. Perhaps more important, this was essentially an observational follow-up study to the original trial, and there were a number of factors discussed below in our review that could have confounded or biased the results. We think it’s inappropriate to conclude, as the headline does, that “Growth hormone reduces risk of osteoporosis fractures” without at least some mention of these limitations.
Osteoporosis affects around 16 percent of U.S. women over the age of 50 and can cause back pain and increase the risk of bone fractures — including hip and other fractures with significant consequences for health and well-being. That means millions of people are affected and, with an aging population, that number is likely to go up. Given the large number of people living with osteoporosis, it makes sense to highlight research that has the potential to mitigate the health risks associated with the condition. But it’s also important to note the limitations of that research.
The release does not mention cost at all, possibly because the study was conducted in Sweden, which has a taxpayer-funded public health system. However, in the U.S., growth hormone treatments can cost hundreds of dollars per month — and it’s not clear if that would be covered by insurance for treating osteoporosis. This high cost is certainly worth mentioning.
The release notes that the rate of bone fractures among study participants declined by 50 percent over the 10-year course of the study and provides an absolute measure of that benefit: 56 percent of participants had experienced a bone fracture before the study, and 28 percent had a bone fracture over the course of the study. We’ll give credit for the quantification, however it must be noted that this before and after comparison is seriously limited in what it can tell us about the benefits of growth hormone treatment — something addressed below under the “Evidence” criterion.
The release doesn’t mention potential harms at all. Given the wide range of potential side effects from growth hormone use — from headache and joint pain to weight gain and weakness — this is a significant oversight.
The release does a fair job of describing the study design. It was a three-year, randomized, double-blind trial of 80 postmenopausal women with osteoporosis, with a seven-year follow-up period. The study also included a control group of 120 women who did not have osteoporosis — at least when the study began. However, the release does not sufficiently highlight the limitations of the study, which are significant. It’s problematic to attribute the benefits observed 10 years after the study began (and 7 years after stopping treatment) entirely to growth hormone therapy as this release does. About a quarter of the women in the study started taking fracture-preventing bisphosphonate drugs during the follow-up period. Is it possible that those drugs had an impact on the fracture rates seen in the study? Without a true placebo control group (patients stopped receiving placebos 18 months into the study and started receiving growth hormone), it’s impossible to differentiate the effects of the growth hormones, the bisphosphonates, or possibly other factors (e.g. fall prevention measures, vitamin D supplements) that were introduced during the study and which may have contributed to the before/after difference in fracture rates.
Another important limitation mentioned by the study authors in their paper (but not in the release) is the small sample size. Only 27 women received the high dose of growth hormone, only 28 received the low dose, and 25 received the placebo. While a study of 80 people can show promise, it’s worth mentioning that this study would need to be replicated on a larger scale in order to determine whether the findings hold up and can be extrapolated to a larger population.
No disease mongering here.
The release provide no information on who funded the study. The research was funded by the University of Gothenburg as well as a variety of public grants. The independent nature of the research was worth mentioning.
The release does not mention other osteoporosis treatment options — such as bisphosphonates, fall prevention interventions, etc. — at all, making it impossible for readers to determine how the growth hormone therapy performed relative to other courses of action.
Many readers may know that growth hormones are available and already used for the treatment of short stature in children. But the release doesn’t establish this for those who might not know. Are these hormones prescription-only? Over the counter? Was it a new formulation developed for use in the study? It’s impossible to tell.
The release establishes what’s new about the study, calling it the largest and longest of any study of growth hormone for osteoporosis to date. However, it would have been useful to inform readers about the long history of research in this area. The release does not mention any previous work, making it difficult for anyone (and impossible for non-experts) to place this new work in context with earlier research — whether that work is 40 years old or more recent.
The release is careful in its use of language. Any problems with the release revolve around what was left out, rather than on the language of the release.