Development of a prediction model for inpatient gout flares in people with comorbid gout

Abstract

ObjectivesHospitalisation is a risk factor for flares in people with gout. However, the predictors of inpatient gout flare are not well understood. The aim of this study was to develop a prediction model for inpatient gout flare among people with comorbid gout.MethodsWe used data from a retrospective cohort of hospitalised patients with comorbid gout from Wellington, Aotearoa/New Zealand, in 2017 calendar year. For the development of a prediction model, we took three approaches: (A) a clinical knowledge-driven model, (B) a statistics-driven model and (C) a decision tree model. The final model was chosen based on practicality and performance, then validated using bootstrap procedure.ResultsThe cohort consisted of 625 hospitalised patients with comorbid gout, 87 of whom experienced inpatient gout flare. Model A yielded 9 predictors of inpatient gout flare, while model B and C produced 15 and 5, respectively. Model A was chosen for its simplicity and superior C-statistics (0.82) and calibration slope (0.93). The final nine-item set of predictors were pre-admission urate >0.36 mmol/L, tophus, no pre-admission urate-lowering therapy (ULT), no pre-admission gout prophylaxis, acute kidney injury, surgery, initiation or increase of gout prophylaxis, adjustment of ULT and diuretics prior to flare. Bootstrap validation of the final model showed adequate C-statistics and calibration slope (0.80 and 0.78, respectively).ConclusionWe propose a set of nine predictors of inpatient flare for people with comorbid gout. The predictors are simple, practical and are supported by existing clinical knowledge.

Gout flare in the critical care setting: diagnostic challenges and treatment options

“…Inpatient gout flare is a multifactorial event influenced by a combination of gout-related and hospitalization-related factors. Although no study to date has examined predictors of gout flares exclusively in the critical care setting, several studies have evaluated factors associated with gout flares in the general inpatient setting [10][11][12][13].…”

“…Hypercholesterolemia was also associated with gout flares (odds ratio [95% confidence interval], 2.01 [1.06-3.83]), which might be explained by the correlation of hyperlipidemia with alcohol intake, obesity, and genetic defects [12]. Jatuworapruk et al [13] identified nine predictors of inpatient gout flares in patients with comorbid gout: preadmission serum urate level >0.36 mmol/L, no use of preadmission urate-lowering therapies (ULT), absence of preadmission gout flare prophylaxis, ULT adjustment, initiation, or increased dose of gout flare prophylaxis, tophus, diuretic adjustment, acute kidney injury, and surgery. These predictors were likely to be associated with gout flares by causing sudden changes in serum urate levels or due to the suboptimal control of gout, all of which increased the risk of gout flares.…”

“…Stopping ongoing ULT during a gout flare is not recommended, because it can lead to a sudden change in serum urate levels, crystal shedding, and ultimately a gout flare [13,38]. The same rationale can also be applied to the critical care setting, where patients are already exposed to numerous potential triggers of gout flares such as acute kidney injury, acute illness, and diuretics.…”

Inpatient gout flare is multifactorial: comment on “clinical characteristics and risk factors for gout flare during the postsurgical period”

“…Inpatient gout flare is a multifactorial event influenced by a combination of gout-related (e.g., serum urate level, tophus) and hospitalization-related factors (e.g., diuretic adjustment, acute kidney injury, surgery) [2]. Surgery may be associated with gout flare through more than one mechanisms, including volume status change, tissue hypoxia and systemic inflammatory response [3,4].…”

Regular pre‐admission urate‐lowering therapy and serum urate testing are associated with a shorter hospital length of stay in people with gout: A nation‐wide population‐based cohort study

“…Inpatient gout flare is associated with worse hospital outcomes. Previous studies suggested that inpatient gout flare contributed to an additional five to six days of hospital admission, 5,6 higher healthcare costs 7 and higher chance of adverse events related to gout flare medications 8 …”