Glucosamine Hydrochloride Affects Subchondral Bone Growth
In a rabbit model of osteoarthritis (OA), treatment with glucosamine hydrochloride significantly reduced subchondral bone turnover, according to a study in Arthritis & Rheumatism (A&R) (2007;56:1537-1548).
Explore This IssueJune 2007
Also By This Author
Glucosamine hydrochloride—a dietary supplement not regulated by the FDA—has long been used to treat OA in humans, with mixed results. In 2001 and 2002, two large clinical trials showed that three years of glucosamine treatment slowed radiographic progression of OA in the knee. Yet in 2006, another randomized, placebo-controlled study in the New England Journal of Medicine found that glucosamine hydrochloride was no better than placebo at controlling knee pain from OA.
Previous studies of the biological workings of glucosamine in animals focused on how the drug affects joint cartilage; this new A&R study was the first to look at how the compound might change the subchondral bone. The authors decided to study subchondral bone changes “because it could explain beneficial outcomes observed in humans in some clinical trials,” says co-author Sheila Laverty, an equine surgeon at the University of Montreal’s veterinary school.
Laverty and colleagues first performed an anterior cruciate ligament transection (ACLT)—a surgical procedure that induces osteoarthritis symptoms—in the knee joints of 16 rabbits. Immediately following the procedure, half the rabbits were given daily doses of glucosamine. After eight weeks, the researchers performed necropsies on all the animals to measure subchondral bone turnover and bone density.
Compared with the control group, glucosamine-treated rabbits had significantly less bone turnover; in most of the bone parameters measured, the glucosamine-treated rabbits were identical to rabbits that had not undergone ACLT. Treatment with glucosamine, Laverty adds, “appeared to offer a protection against the reduction in bone mineral density, subchondral bone plate thickness, and bone connectivity associated with the development of osteoarthritis.”
Still, Laverty cautions against extrapolating these results in the rabbit model to humans. In the model, glucosamine was given from disease onset, while humans are usually studied much later in the disease trajectory. However, she says these findings “could provide some support for the use of glucosamine immediately following joint injury.”
Socioeconomic Factors Affect Access to Rheumatology Care
People with rheumatic diseases, studies have shown, have better treatment outcomes if they see a rheumatology specialist. But are certain segments of the patient population more likely than others to seek and receive specialty care?
To find out, two studies in the May issue of Arthritis Care & Research surveyed almost 1,000 systemic lupus erythematosus (SLE) patients (2007;57:593-600, 601- 607). The first found that elderly, male, and lower-income patients were the least likely to have seen a specialist in the previous year. The second found that Medicaid patients traveled much further than non-Medicaid patients to see the doctor (whether specialist or not) who treated their condition.
The 982-patient cohort used for both studies was recruited mostly from non-clinical sources—Web sites, newsletters, and lupus support groups—making it much more diverse than if patients were sampled only from academic research centers, says co-author Jinoos Yazdany, MD, MPH, adjunct assistant professor of medicine at the University of California, San Francisco (UCSF). Researchers telephoned each patient to ask detailed questions about their disease history and socioeconomic background—including ethnicity, educational level, income, and medical insurance. The patients were all English speakers and came from 41 different states.
For the first study, researchers focused on how many times patients had seen a rheumatology specialist in the previous year. Patients 65 or older were significantly less likely than younger patients to have seen a specialist at least once (65%, compared to 79% of patients younger than 65); similarly, men were less likely than women to have reported at least one visit (63% versus 79%); as were patients with a household income less than $40,000 (72%, compared to 81% of patients with incomes higher than $40,000).
The seeds of the second study arose at the bedside. While working at the lupus clinic at UCSF, Dr. Yazdany noticed that many of her Medicaid patients were traveling extremely long distances for care. “Some traveled six hours and even had to stay overnight in San Francisco,” she recalls. The patients weren’t making the trek because they wanted to be treated at an academic center, but because rheumatologists closer to home didn’t accept Medicaid. Indeed, the same telephone survey found that patients with only Medicaid insurance traveled an average of 42 miles for care, while patients with private insurance traveled about 24 miles.
These results are especially worrisome if the extra distance means poorer treatment outcomes. “You can imagine that if a patient is traveling six hours in order to see their rheumatologist, if they get sick and don’t have somebody to drive them, they’re not going to make the trip,” she says. “They’ll either have to get care in emergency departments or not get care at all.”
Dr. Yazdany attributes these demographic and socioeconomic disparities to two major factors: physician awareness and flaws in the U.S. healthcare system. “If the patient’s generalist physician doesn’t have a good understanding of lupus, they may not make a timely and appropriate referral to a specialist,” she says. Moreover, in the last few years, because Medicaid physician reimbursements have dropped significantly, many rheumatologists in private practice say they can no longer afford to accept Medicaid patients. “That’s an example of a national policy that’s directly influencing who’s receiving care,” she laments.
Virginia Hughes is a medical journalist based in New York City.