Conference Coverage

VIDEO: Hip, knee replacements fall in Danish RA patients


Key clinical point: During 1996-2011, the rate of total hip and knee replacement surgeries fell among patients with rheumatoid arthritis and rose in the general population, so that by 2011 the rates were fairly close in these two groups.

Major finding: RA patient hip replacements fell from nearly 9/1,000 person-years in 1996 to about 4.5/1,000 person-years in 2011.

Data source: Records from more than 300,000 people in the Danish National Patient Register.

Disclosures: Dr. Dreyer has received lecture fees from Merck Sharp & Dohme and UCB. Dr. Landewé has received consulting fees from several drug companies.



– The rates of both total hip and total knee replacement surgeries dropped among Danish patients with rheumatoid arthritis since the mid-1990s, reductions that were coincident with more widespread use of biologic drugs as well as with other improvements in care, according to analyses of Danish national health records.

“The introduction of guidelines [on biologic drug use] in 2002 and increasing use of biologic drugs [as a result] may have contributed to this positive development,” Lene Dreyer, MD, said at the European Congress of Rheumatology. Other factors that may have also contributed include widespread use of conventional disease-modifying antirheumatic drugs (DMARDs) and adoption of a treat-to-target strategy by many clinicians.

In 1996, the first year studied and before any biologic DMARDs were routinely used for rheumatoid arthritis, the rate of total knee replacement was nearly 6/1,000 person-years among RA patients, compared with a 0.42/1,000 person-years rate in the general adult Danish population, a roughly 14-fold excess among the RA patients, Dr. Dreyer reported. But by 2016, ”this gap had almost disappeared,” she said in a video interview. “It seems like rheumatologists in Denmark are doing a good job” treating RA patients.

Limelight Video

That may have been especially true subsequent to 2002, when the Danish Institute for Rational Pharmacotherapy issued recommendations that opened the door to wider use of biologic DMARDs, such as tumor necrosis factor inhibitors, to treat RA patients, noted Dr. Dreyer of Gentofte University Hospital, Copenhagen. During 2003-2011, use of total knee replacement surgery in RA patients fell by an average annualized rate of 0.2 surgeries/1,000 person-years. But among the general Danish population the average annualized rate of knee surgeries rose by 0.08/1,000 person-years.

“This is a very important finding,” commented Robert Landewé, MD, PhD, professor of rheumatology at the Academic Medical Center in Amsterdam. “It is extremely difficult to test the effect of the introduction of the [biologic DMARD] guidelines,” he cautioned. But he highlighted the positive finding that the excess of hip and knee replacement surgeries in patients with RA, compared with the general population, had recently narrowed.

Dr. Dreyer and her associates used records from the Danish National Patient Register to compare 29,427 patients with incident RA during 1996-2011 with more than 290,000 matched control individuals. All people studied had not undergone knee or hip replacement surgery prior to their entry into the study. The researchers used an “interrupted time series analysis” to examine the possible impact of the introduction of widespread access to biologic DMARDs starting in 2003.

The analysis showed that the rate of total hip replacements in 1996 was nearly 9 surgeries/1,000 person-years among RA patients and nearly 3/1,000 person-years in the general population, a threefold excess for RA patients. This rate fell by an average annual rate of 0.38/1,000 person-years among RA patients both before and after 2002, so that by 2011 the rate was roughly half the 1996 rate, about 4.5/1,000 patient-years. The rate in the general population rose during 1996-2011, and by 2011 was nearly 4/1,000 person-years and so nearly the same as RA patients. Wider availability of biologic DMARDs for RA patients starting in 2003 did not have an apparent impact on the rate of total hip replacement.

In contrast, wider use of biologic DMARDs appeared to have an effect on the rate of total knee surgeries among RA patients. During 1996-2001, the rate rose by an annual average of 0.19/1,000 person-years, very similar to the 0.21/1,000 person-years annual rise in the general Danish population. However, during 2003-2011, the average annual rate of total knee surgery fell by 0.20/1,000 person-years in the RA patients but continued to rise at an annual average rate of 0.08/1,000 person-years in the general population, Dr. Dreyer reported.

Additional Danish registry data exist for patients who received biologic DMARDs, and Dr. Dreyer said that she and her associates hope to use this to further examine the impact of these drugs on patient outcomes.

Dr. Dreyer has received lecture fees from Merck Sharp & Dohme and UCB. Dr. Landewé has received consulting fees from several drug companies.

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