Persistent and nonepisodic foot pain in hyperuricemia is associated with ultrasound features of monosodium urate deposition within joints that is responsive to urate-lowering therapy, a case-control study shows.
, reported Yousef Mohammed Alammari, of the department of rheumatology, Tallaght University Hospital, Dublin, and associates.
Furthermore, the researchers wrote in Annals of the Rheumatic Diseases, their findings serve as “potential rationale” for reclassification of the ACR/EULAR 2015 gout classification criteria.
The research team noted that the gout classification criteria from the two rheumatology organizations require a history of a “prior episode of swelling, pain, or tenderness of a peripheral joint/bursa before confirmation either through MSU crystal identification in synovial fluid or through achieving a score of greater than 8 using a predefined scoring system of radiological, laboratory, and clinical features.”
Yet, emerging evidence suggests that foot pain could be a preclinical and clinical phase of gout that might occur prior to a first episodic gout attack, the investigators noted.
The current study involved 16 hyperuricemia individuals with persistent, nonepisodic foot pain who did not fulfill ACR/EULAR 2015 gout classification criteria but received febuxostat 80 mg once daily for 3 months. Controls were 15 individuals with asymptomatic hyperuricemia.
Results showed that double contour sign erosion and tophus occurred in 44%, 37%, and 37% of the cases, respectively, whereas no ultrasound features of gout were seen in the controls.
No significant difference in baseline serum urate was observed between the cases (450 plus or minus 18 mg/dL) and controls (426 plus or minus 7; P = nonsignificant), but at 1- and 3-month time points, serum urate fell in the cases (200 plus or minus 18; P less than 0.001 and 223 plus or minus 28; P less than less than 0.001).
In the cases, baseline 24-hour pain visual analogue score (65 plus or minus 4.9) reduced at 1 month (41 plus or minus 6.6; P = 0.001) and 3 months (33 plus or minus 7.2; P less than 0.001) of urate lowering therapy, as did the 7-day pain visual analogue score (70 plus or minus 4.7) scores (44 plus or minus 7.1; P less than 0.001 at 1 month; 38 plus or minus 8; P less than 0.001 at 3 months).
The Manchester Foot Pain and Disability Index also decreased at 1 month (21 plus or minus 2.9; P = 0.019) and 3 months (17 plus or minus 2.8; P = 0.012).
When the investigators grouped the cases according to the presence (n = 7) or absence (n = 9) of double contour sign on baseline ultrasound, no differences were observed for baseline pain scores.
However, after treatment with ultrasound, 24-hour pain visual analogue scores were significantly lower in double contour positive patients at 1 month and 3 months.
In addition, the researchers found, the 7-day pain visual analogue scores were significantly lower in double contour positive patients at 1 month and 3 months. No significant differences were seen between double contour positive and double contour negative patients in the Manchester Foot Pain and Disability Index or serum urate at 1 or 3 months of ultrasound.
The investigators noted that their findings indicated that persistent, nonepisodic foot pain in hyperuricemia was both associated with ultrasound features of monosodium urate deposition and was responsive to urate lowering therapy.
“Symptomatic hyperuricemia occurring prior to episodic gout therefore represents an earlier or alternative disease presentation,” they wrote. “Changes to the ACR/ EULAR classification criteria to include nonepisodic foot pain in the presence of [ultrasound] features of gout may increase the sensitivity of disease classification at an early stage, leading to improved future treatment strategies and long-term outcomes.”
No disclosures were declared.
SOURCE: Alammari YM et al. Ann Rheum Dis. 2018. doi: 10.1136/annrheumdis-2018-214305.