Gout flare patterns vary greatly among patients
Patterns of flares over time vary greatly among patients with gout, although time-dependent reporting, including the number of days with flare or area under the pain-by-time curve, could allow for a more accurate measure of flare burden, according to findings published in BMC Rheumatology.
“Although the presence of being in the state of flare and the time characteristics of a single flare have been defined, the optimal method of reporting flares over time is unclear,” Nicola Dalbeth, MD, MBChB, FRACP, of the University of Auckland in New Zealand, and colleagues wrote. “In clinical trials of urate-lowering therapy, flares are typically reported as the percentage of participants with at least one flare or mean number of flares over a specified time period. In studies of anti-inflammatory prophylaxis, additional methods have been used including time to first flare, severity of flares and average duration of all flares.”
“The lack of standardization of flare reporting makes comparison between different treatments difficult,” they added. “Furthermore, categorization of flare data may not capture the severity, duration or impact of flares.”
To analyze the patterns of gout flare, as well as to evaluate the value to various methods of flare reporting in clinical trials, Dalbeth and colleagues studied flare diary entries from participants in randomized, controlled trial. In that study, 120 patients with gout were randomly selected to one of three treatment arms — milk powder enriched with glycomacropeptide and G600 milk fat extract, a skim milk powder control group or a lactose control group.
For 4 months, participants completed daily flare diary entries, self-reporting on both flare occurrence and pain intensity using the 0 to 10 Likert scale. The researchers evaluated pain-by-time plots for various methods of flare reporting, both for both self-reported flares and those defined by the classification tree developed by Gaffo in 2012. In addition, they analyzed concurrent validity for each reporting method.
According to the researchers, although gout flares largely followed a “typical” pattern — peaking on day one and resolving over the course of 2 weeks — individual pain-by-time plots demonstrated a wide variation of pain intensity, duration and frequency. During the total study period, 70% of participants reported experiencing at least one flare that was unlike a “typical” flare. In addition, the time to first self-reported flare correlated poorly with other measures of disease activity and methods of flare reporting.
However, the number of days with flare, based on self-reporting or the Gaffo definition, and area under the pain-by-time curve both correlated most strongly with other measures.
“Patterns of flare over time vary widely in individuals with gout,” Dalbeth and colleagues wrote. “Time-dependent reporting strategies such as the number of days with flare or the area under the pain-by-time curve correlate well with other measures of gout disease severity and may provide a more accurate and comprehensive assessment of flare burden.” – by Jason Laday
Disclosure: Dalbeth reports grant funding from Amgen and AstraZeneca/Ironwood; speaking fees from AbbVie, Janssen and Pfizer; and consulting fees from Horizon and Kowa. Please see the full study for additional authors’ disclosures.