Presence of gout is associated with increased prevalence and severity of knee osteoarthritis among older men: results of a pilot study

Abstract

Background: Gout and osteoarthritis (OA) are the most prevalent arthritides, but their relationship is neither well established nor well understood.

Objectives: We assessed whether a diagnosis of gout or asymptomatic hyperuricemia (AH) is associated with increased prevalence/severity of knee OA.

Methods: One hundred nineteen male patients aged 55 to 85 years were sequentially enrolled from the primary care clinics of an urban Veterans Affairs hospital, assessed and categorized into 3 groups: gout (American College of Rheumatology Classification Criteria), AH (serum urate ≥6.8 mg/dL, no gout), and control (serum urate <6.8 mg/dL, no gout). Twenty-five patients from each group subsequently underwent formal assessment of knee OA presence and severity (American College of Rheumatology Clinical/Radiographic Criteria, Kellgren-Lawrence grade). Musculoskeletal ultrasound was used to detect monosodium urate deposition at the knees and first metatarsophalangeal joints.

Results: The study showed 68.0% of gout, 52.0% of AH, and 28.0% of age-matched control subjects had knee OA (gout vs control, P = 0.017). Odds ratio for knee OA in gout versus control subjects was 5.46 prior to and 3.80 after adjusting for body mass index. Gout subjects also had higher Kellgren-Lawrence grades than did the control subjects (P = 0.001). Subjects with sonographically detected monosodium urate crystal deposition on cartilage were more likely to have OA than those without (60.0 vs 27.5%, P = 0.037), with crystal deposition at the first metatarsophalangeal joints correlating most closely with OA knee involvement.

Conclusions: Knee OA was more prevalent in gout patients versus control subjects and intermediate in AH. Knee OA was more severe in gout patients versus control subjects.

Figure 1. Patient Recruitment/Enrollment Flow Diagram

Figure 2. Prevalence of knee OA, and impact of BMI on knee OA among control, AH and gout groups

A, Presence of gout predicts increased prevalence of knee OA. Control, AH and gout subjects were assessed for presence of knee OA using ACR Clinical/Radiographic or Clinical OA criteria, as indicated (*P<0.05 vs. control group). B, Presence of gout predicts increased prevalence of knee OA among non-obese patients. Control, AH and gout subjects were stratified into non-obese (BMI<30) and obese (BMI≥30) subgroups, and the prevalence of knee OA (ACR Clinical/Radiographic criteria) was determined for each subgroup (*P<0.05 vs. corresponding control group).

Figure 3. Impact of cartilage crystal deposition and acute gout attacks on presence of knee OA

A, Presence of MSU crystal deposition in MTP but not knee joints correlates with prevalence of knee OA. Knees and 1^st MTP joints were examined for crystal deposition by MSKUS. White columns indicate patients with no overt crystal deposition at the examined sites; black columns indicate the presence of crystal deposition. B, Presence of knee OA correlates with presence of macroscopic MSU crystal deposition identified by MSK-US, but not with presence of crystals in OA-affected knee joints. Black columns indicate the presence of crystals in any joint examined (all knees and 1^st MTPs); white bars indicate the presence of crystals in OA-affected knee joints only. C, Prior gout attacks in affected knees do not correlate with presence of knee OA. Gout patients with self-report of ≥1 gouty attacks in the knees (n=16), vs. a history of gouty attacks only in locations other than the knees (n=9) were assessed for the presence of knee