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Wednesday, October 21, 2009: 11:15 AM
203 B (Pennsylvania Convention Center)
Presentation Number: 2034
Purpose: It is generally acknowledged that renal impairment is associated with a higher incidence of AHS. However, no study has assessed this in a large population. This study assessed the incidence of AHS among renally impaired patients who are commercially insured through administrative claims data using a clinically validated algorithm.
Methods: This study applied a retrospective cohort design to determine AHS incidence among treatment-naive allopurinol users with and without renal impairment within two large commercial datasets. A 6-month washout period prior to the initial (index) allopurinol prescription was used to define treatment-naive patients. During this washout period, patients were defined as renally impaired based on ICD-9 and HCPCS codes. The presence of AHS was then examined using a multi-step process. First, an uninterrupted allopurinol exposure period was identified. Second, presence of AHS symptoms within the appropriate temporal sequence was applied, and severity of the AHS episode was assessed. Episodes were considered invalid if alternative disease states or medications could account for similar AHS signs and symptoms, or if additional allopurinol exposure periods occurred after the AHS episode. The primary outcome was AHS incidence among the two cohorts (renally impaired vs non–renally impaired) computed as the total number of patients with AHS divided by the total number of allopurinol users within the respective cohort. Logistic regression analyses were conducted to determine statistically significant differences.
Results: A similar proportion in both datasets were found to be renally impaired (10.5% and 12.8%). Overall, renally impaired patients were 2.5 to 4 years older (P<0.001), less likely to be male (P<0.001), more likely to use a diuretic (P<0.001), and had a higher Charlson comorbidity index (P=0.001). Presence of AHS among renally impaired patients ranged from 0.41% (n=24) to 0.72% (n=63). The majority of AHS episodes among renally impaired patients were characterized by acute renal failure (ARF; 20 of 24 and 57 of 63). Unadjusted estimates indicate that the incidence of AHS was 3 to 4 times higher among renally impaired patients compared with non–renally impaired patients (P<0.007). After controlling for age, gender, comorbidity burden, gout diagnosis, and diuretic use, renally impaired patients were significantly more likely to have AHS (OR 2.06; 95% CI 1.21-3.51; P=0.010 and OR 3.29; 95% CI 2.31-4.70; P<0.001).
Conclusion: Similar results were found in both datasets with the incidence of AHS being 2-3 times higher in renally impaired. Also, a majority of AHS episodes were characterized by ARF, suggesting a potential relationship between allopurinol and ARF. Further research is needed to better understand predictors and overall characteristics of patients susceptible to developing AHS, and if there is a causal relationship between allopurinol and ARF.
Methods: This study applied a retrospective cohort design to determine AHS incidence among treatment-naive allopurinol users with and without renal impairment within two large commercial datasets. A 6-month washout period prior to the initial (index) allopurinol prescription was used to define treatment-naive patients. During this washout period, patients were defined as renally impaired based on ICD-9 and HCPCS codes. The presence of AHS was then examined using a multi-step process. First, an uninterrupted allopurinol exposure period was identified. Second, presence of AHS symptoms within the appropriate temporal sequence was applied, and severity of the AHS episode was assessed. Episodes were considered invalid if alternative disease states or medications could account for similar AHS signs and symptoms, or if additional allopurinol exposure periods occurred after the AHS episode. The primary outcome was AHS incidence among the two cohorts (renally impaired vs non–renally impaired) computed as the total number of patients with AHS divided by the total number of allopurinol users within the respective cohort. Logistic regression analyses were conducted to determine statistically significant differences.
Results: A similar proportion in both datasets were found to be renally impaired (10.5% and 12.8%). Overall, renally impaired patients were 2.5 to 4 years older (P<0.001), less likely to be male (P<0.001), more likely to use a diuretic (P<0.001), and had a higher Charlson comorbidity index (P=0.001). Presence of AHS among renally impaired patients ranged from 0.41% (n=24) to 0.72% (n=63). The majority of AHS episodes among renally impaired patients were characterized by acute renal failure (ARF; 20 of 24 and 57 of 63). Unadjusted estimates indicate that the incidence of AHS was 3 to 4 times higher among renally impaired patients compared with non–renally impaired patients (P<0.007). After controlling for age, gender, comorbidity burden, gout diagnosis, and diuretic use, renally impaired patients were significantly more likely to have AHS (OR 2.06; 95% CI 1.21-3.51; P=0.010 and OR 3.29; 95% CI 2.31-4.70; P<0.001).
Conclusion: Similar results were found in both datasets with the incidence of AHS being 2-3 times higher in renally impaired. Also, a majority of AHS episodes were characterized by ARF, suggesting a potential relationship between allopurinol and ARF. Further research is needed to better understand predictors and overall characteristics of patients susceptible to developing AHS, and if there is a causal relationship between allopurinol and ARF.
Keywords: outcome measures, population studies and renal disease
Disclosure: D. Khanna, UCB, 9, Takeda, 9, Actelion , 5, Fibrogen, 5, Gilead, 5, Savient, 5, Takeda, 5, Actelion , 9, Takeda, 9, Abbott , 9, UCB, 9, Actelion , 9, Gilead, 9 ; B. J. Pandya, Takeda, 3 ; A. O. D'Souza, Xcenda, 5 ; B. L. Meissner, Xcenda, 5 ; R. Kamalakar, Takeda, 3 ; V. Harikrishnan, Takeda, 3 .