A new study attempts to find consensus on a challenging problem: When is gout considered to be in remission?
The study, published in the journal Arthritis Care & Research in September, tentatively identifies serum urate levels, flares, tophi, pain and a patient global assessment as criteria to determine remission, though opinions among experts vary as to how long symptoms must be gone.
In three rounds of questionnaires sent to 88 gout experts worldwide, rheumatologist Huge de Lautour of the Auckland District Health Board in New Zealand and colleagues narrowed down the potential criteria to those with more than 80 percent agreement among experts, arriving at the final five domains. Though consensus was forthcoming in most cases, the field was nearly evenly split in whether the timeframe for remission should be six months without symptoms, or one year. Researchers also questioned whether the crystalline uric acid deposits known as tophi must entirely vanish to qualify as remission from gout, or whether they must simply regress.©kenary820/Shuttersstock.com
Rheumatology Network spoke with Dr. de Lautour about the findings and the difficulty of defining remission for a reoccurring illness like gout. In the future, the researchers plan to validate these proposed criteria in a pre-existing data set from a drug study, de Lautour said. The researchers aren't yet sure of the benchmark they'll use to validate remission, he said, but might use dual-energy computed tomography (CT) to quantify the presence or absence of tophi.
Rheumatology Network: It seems surprising that there are no remission criteria for gout. Why is this?
de Lautour: Probably a number of reasons: Not as much interest in gout compared to other causes of arthritis (and money). There were no validated outcome measures for gout until recently, and there still are no validated definitions for important domains of gout such as flares. Even with a composite outcome/remission criteria, there is uncertainly about the validity, as patients did not give equal weighting to each components of domains for remission. And finally, what is the definition of remission in gout? Gout is a disease which can have minimal symptoms between attacks, [so] does that mean the patient is in remission between attacks?
Rheumatology Network: What is known about the possibility of remission for gout? What kind of treatments are associated with remission, and about what percent of patients achieve some kind of remission?
de Lautour: Theoretically, and even in current practice, "remission" is possible. Even with simple medications such as allopurinol, excellent control of serum urate is possible — and therefore, remission. I don’t know of a percentage; there is high variability in patient compliance, which is the most important factor. I would think as an estimate 75 percent of patient will achieve remission if they take adequate urate lowering therapy.
Rheumatology Network: Is there a point of no return with gout in which remission is impossible?
de Lautour: I think so. If patient has extensive tophi, then the time required for tophus to resolve (which they will once serum urate is low) will be many, many years. Also the tophus causes damage such as bony erosion, which will result in secondary osteoarthritis of the joint and chronic pain, therefore, never in remission.
Rheumatology Network: What were the proposed preliminary remission criteria that emerged from your study?
de Lautour: The criteria from the study are relatively strict and will likely mean patients described above will not achieve remission. The remission criteria from the study are below. All five must be met.
Rheumatology Network: It seemed that timeframes were a particularly difficult issue - why was there a lack of consensus on the timeframe for remission? What sort of research would be needed to resolve this question?
de Lautour: The split in opinion results from those wanting six months, so the criteria could be used in clinical trials (feasibility) versus 12 months which would be more clinically appropriate (validity, capturing all those who will have attacks) but difficult for a clinic trial. I think the answer is looking at a cohort of patients which didn’t flare in the last six months and then following them for another six months and seeing the proportion of those who continue not to flare. If this is high, then six months is probably sufficient timeframe.
Serum urate < 0.36mM (6 mg/dl) at least twice over last 12 months#, and no values ≥ 0.36mM (6 mg/dl)^
No flares during last 12 months
Pain due to gout < 2 at least twice over last 12 months#, and no values ≥ 2*
Patient global assessment
Patient global assessment of gout disease activity < 2 at least twice over last 12 months#, and no values ≥ 2*
*using 10cm visual analogue scale or 10-point Likert-type scale
# measurements at equal distances apart over the 12 months
^ all intervening measurements must be below 0.36mM (6mg/dl)