Introduction
Gout is one of the most common inflammatory joint diseases, and is
caused by an aberrant purine metabolism and a deposition of monosodium
urate crystals (MSU) in and around the joints.1 Its
prevalence ranges from <1% to 6.8% amongst different races,
and has shown an apparent rising and younger trend in recent
years.1 Tophi caused by a long-term deposition of MSU
crystals is the characteristic symptom of advanced
gout.2 As reported, tophi develops in approximately
12-35% of gout patients.3 However, the clinical
significance of tophi is often underestimated. In fact, tophi may lead
to several significant complications, such as irreversible joint
deformities and dysfunctions, severely limited range of motions, bone
destructions and even fractures.4,5 Superficial tophi
can cause infections and ulceration.6 It can also
cause entrapment neuropathy, such as carpal tunnel syndrome and
radiculopathy.7,8 The ideal treatment choice for
patients with serious tophi complications is surgery, which has certain
risks and may be quite expensive.9 Overall, tophi
seriously impacts the life quality and longevity of patients, not to
mention a huge economic burden.10
Previous researches have indicated that multiple factors are related to
tophi formation, including serum uric acid level, disease duration, age,
gender, family history, gout flare frequency, incidence of obesity,
hypertension, hyperlipidaemia, renal dysfunction, kidney stone, coronary
heart disease, and upper limb joint
involvement.2,11,12 Considering the hazards of tophi,
it is significant to establish an accurate prediction tool to confirm
and evaluate the various influences of the above potential associated
risk factors on tophi formation. This is likewise beneficial to the
early prevention, diagnosis and treatment of tophi. However, there are
no relatively existing studies on this matter. Thus, this study was
conducted to develop a simple yet valid prediction model to identify the
predictors of tophi formation amongst people with gout.