'Gout-36' rule simple, sensitive for classifying flare risk in hospitalized patients
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A group of researchers have developed a rule that can help identify patients at high risk for gout flare during a hospital stay, according to data published in Rheumatology.
Dubbed ‘Gout-36,’ the rule has four items: No pre-hospitalization prophylaxis against gout flare, no pre-hospitalization urate-lowering therapy, the presence of tophus and a pre-admission serum urate level of more than 0.36 mmol/l within the previous year.
“Hospitalized people with gout are not well studied and most studies focus on people with gout in the outpatient setting,” Kanon Jatuworapruk, MD, of Thammasat University, in Pathum Thani, Thailand, and the University of Otago, in Wellington, New Zealand, told Healio Rheumatology. “However, many people develop gout flares during their hospital stay, which leads to more medication, higher costs and longer stays. Hospital settings differ from outpatient setting — people are more vulnerable, they are older, with multiple active comorbidities.”
“There is also a different set of gout flare triggers in hospital settings — surgery, acute kidney injury, diuretic adjustment and withdrawal of gout medications,” he added. “The treatment approach for hospitalized people with gout is generally passive — treat gout flare when it happens — and there is no recommendation on how to prevent flare. First, we should be able to tell who are at risk, then we may be able to find a way to prevent flare.”
To develop and validate a stratification tool for flare risk in patients hospitalized for non-gout conditions, Jatuworapruk and colleagues analyzed a set of nine previously identified predictors of inpatient gout flare. These predictors, and their corresponding regression coefficients, were derived from a logistic regression analysis of 625 hospitalized patients in New Zealand with comorbid gout. Among this cohort, 14% of patients experienced flare.
For the final selection process, the researchers focused on items that were simple, user friendly, and available on a patient’s first day of hospitalization. Based on these criteria, they chose the four items within their “first day rule,” which they later renamed as the “Gout-36” rule. As part of this rule, two or more items are required for the classification of “high risk” for gout flare. The Gout-36 rule was validated using a prospective cohort of 284 hospitalized patients from Thailand and China with comorbid gout.
According to the researchers, the Gout-36 rule demonstrated a sensitivity of 75%, a specificity of 67%, and an area under the curve of 0.71 for classifying patients at high risk for gout while hospitalized. The researchers also developed four risk groups: Patients who met zero items were classified as low risk, those who met one item were of moderate risk, those with two items were at high risk, and patients with three or four are considered at very high risk.
In a patient population with “frequent” in-hospital gout flare — 34% overall — 80% of those classified as ‘very high risk’ would ultimately experience a flare, the researchers wrote. Meanwhile, 11% of those classified as ‘low risk’ would develop gout flare.
“The Gout-36 rule gives doctors an idea of who is likely to have gout flare during that particular hospital stay,” Jatuworapruk said. “It is easy to adopt in routine hospital practice, requires little or no resources and allows for risk stratification on the first day of hospital admission. It is best to use it on the first day to allow comprehensive planning.”
“Regarding high-risk patients, physicians should consider close monitoring and ensure that existing gout medications are continued — unless contraindicated,” he added. “For those without existing flare prophylaxis, low-dose colchicine may be helpful during hospitalization, but further study is needed.”
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