Background/Purpose:  

Proponents of improving quality of gout care have suggested various gout quality indicators, but no study to date has shown the link between good quality care and improved outcomes. The aim of the study was to assess  whether appropriate good quality care for gout, including uninterrupted urate-lowering therapy (ULT) and achievement of target serum urate <6 mg/dl, is associated with reduced gout-related utilization.

Methods:

This retrospective study utilized the Veterans Affairs (VA) administrative and clinical databases claims from fiscal years 2002 to 2010, using the presence of an International Classification of Diseases, ninth revision (ICD-9) code, 274.xx in a VA outpatient or inpatient visit to define the gout cohort.  A 90-day or longer filled VA prescription for allopurinol, probenecid or febuxostat in a patient with gout was considered as exposure to ULT.  The two independent predictors of interest were Medication Possession Ratios (MPRs) for each ULT and achievement of target sUA < 6 mg/dl.  The MPR denominator was the number of days from index to the exhaustion of the last prescription and the numerator was days of medication supplied over that period from first to last prescription. We used regression analyses with a quasi-Poisson distribution given the type of data, limiting the analyses to patients with >=1-year of follow-up.  The outcome was counts of visits with an offset for the number of years in the cohort. 

Results:

The gout cohort consisted of 376,421 patients with mean age 70 years, 99% were male and 61% were married.  Their exposure to various medications for the treatment of gout was as follows: allopurinol, 70%; febuxostat, 0.3%; and probenecid, 3%.  Mean follow-up was 6.2 years (standard deviation, 2.9). Higher MPRs for allopurinol, febuxostat, and probenecid were associated with significantly lower outpatient, urgent care, emergency room and overall visits (all p-values <0.0001; Table 1).  Achievement of target sUA < 6 mg/dl was associated with significantly lower gout-related outpatient, inpatient, urgent care and emergency room visits (all p-values <0.012; Table 1).  Conversely, a higher proportion of sUA levels >=6 mg/dl was associated with higher gout-related outpatient, inpatient, urgent care and emergency room visits (all p-values <0.00001).

Table 1. Association of MPR for three ULTs and of achievement of target sUA < 6mg/dl with future gout-related health care utilization

	Incidence rate ratio* [p-value]
	Any visit	Outpatient visit	ER visit	Urgent care	Inpatient
Adherence to ULT
Allopurinol MPR (n=231,131)	0.50 [p<0.00001]	0.50 [p<0.00001]	0.32 [p<0.00001]	0.38 [p<0.00001]	0.80 [p=0.00005]
Febuxostat MPR (n=759)	0.64 [p=0.0031]	0.66 [p=0.0074]	0.38 [p=0.00073]	0.28 [p=0.0078]	0.85 [p=0.661]
Probenecid MPR (n=10,514)	0.47 [p<0.00001]	0.47 [p<0.00001]	0.45 [p<0.00001]	0.40 [p=0.00374]	0.89 [p=0.63]
Achieving target sUA
Any sUA <6 mg/dl (n=161,069)	0.99 [p=0.11]	1.02 [p=0.0116]	0.79 [p<0.00001]	0.57 [p<0.00001]	0.90 [p=0.0105]
Proportion of sUA levels >=6 mg/dl (n=161,069)	1.72 [p<0.00001]	1.62 [p<0.00001]	2.43 [p<0.00001]	4.05 [p<0.00001]	2.87 [p<0.00001]

*Incidence rate ratio for each outcome is for patients with MPR of 1 versus 0

Conclusion:

This is the first study to find evidence of association of poor quality of care (lower ULT MPR and non-achievement of target sUA) with greater gout-related health care utilization, especially for emergency room and urgent care visits.  Improvement in quality of gout care may reduce expensive gout-related utilization of emergency room and urgent care resources.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/poor-quality-of-gout-care-is-strongly-associated-with-higher-gout-related-health-care-utilization/