People with ankylosing spondylitis or psoriatic arthritis who take cholesterol-lowering drugs called statins seem to live longer than people who don’t take them, according to researchers at Massachusetts General Hospital in Boston. They presented their findings recently at the American College of Rheumatology’s 2016 Annual Meeting.
In a previous study, Massachusetts General researchers found that people with rheumatoid arthritis (RA) who took statins lived longer, and they wanted to know if the drugs would offer a similar benefit to patients with other types of inflammatory arthritis, such as ankylosing spondylitis (AS) and psoriatic arthritis (PsA). AS mainly affects the spine, especially the sacroiliac joint where the spine meets the pelvis. PsA affects joints as well as skin.
For the study, the investigators used a large, general population database from the United Kingdom to identify nearly 3,000 people with AS or PsA who began taking statins between 2000 and 2014. Those patients were matched with an equal number of patients with the same conditions who didn’t take statins. The two groups varied in many respects, including age, body mass index (BMI), health problems and medication use, so the researchers used a statistical method called “propensity matched scoring” to try to account for those factors that might influence the study results. By eliminating these factors, any observed differences between the groups could more accurately be attributed to statin use instead of to something else. Another group of patients, whose characteristics were not matched, was compared to the two other groups.
During the five years of follow-up, 271 patients in the statin group died compared with 376 in the non-statin group – a 33 percent lower mortality rate. Amar Oza, MD, a rheumatologist at Massachusetts General Hospital and lead study author, says that’s a greater statin-related reduction in mortality than is seen among the general population or people with RA.
Statins and Inflammation
Why is that? For one thing, people with inflammatory types of arthritis – like RA, PsA and AS –are known to have an increased risk of cardiovascular disease. Although they have the same risk factors for heart problems as the general population, including obesity (which is especially increased in PsA), a sedentary lifestyle, poor diet, high blood pressure and high cholesterol, they have an additional risk factor: systemic (body-wide) inflammation. Some rheumatologists think the damage to blood vessels from inflammation may be greater than from any other risk factor.
That’s where statins come in. The drugs are used to lower high cholesterol levels, long believed to contribute to heart disease. But they have the added benefit of also reducing inflammation, which may explain why they seem to cut the risk of death from cardiovascular disease among people with AS and PsA even more than they do among the general population.
Dr. Oza says lowering systemic inflammation is an important part of treating cardiovascular disease. Whether that can be done with diet and lifestyle changes alone or medications are needed is a matter of some debate.
Potential problems with the study
The study authors note that their research has limitations. For instance, they were not able to look at specific causes of death or to determine whether a link exists between early death and disease severity. It’s also not possible to know from the research, which was presented in abstract form at a conference and not in a peer-reviewed journal, which variables were included in the propensity score-matched group, says Kaleb Michaud, PhD, co-director of the National Data Bank for Rheumatic Diseases and an assistant professor at the University of Nebraska Medical Center in Omaha.
“I’d want to know if the patients on statins were just better patients or received better care that may [have impacted] the outcome,” he explains. “My biggest concern [about the study] is the unmatched cohort.”
Michaud is referring to the group of patients who didn’t take statins but were not propensity score-matched to eliminate other factors that might have influenced the results. At 44 percent, their mortality rate was higher than that of both the statin and propensity-matched cohort.
Dr. Oza explains that their higher mortality rate is not surprising because statins are more commonly used in sicker patients – a group that would be expected to have higher mortality rates than those who aren’t as ill.
Also not discussed in the abstract are the side effects of statins. One is an increased risk of diabetes, which is already higher in people with inflammatory arthritis than in those without the disease. A study by Michaud and colleagues published online in November 2016 in Annals of the Rheumatic Diseases found that statins increased the likelihood of developing diabetes in people with RA by 50 percent on average.
Still, Michaud says, “There is evidence to suggest that this risk is outweighed by the [cardiovascular] benefits [of the drugs].”
Author: Linda Rath for the Arthritis Foundation