Wilson's Disease: Nationwide Analysis of Temporal Trends in Hospitalizations, Demographic Variations, Cost of Care, Comorbidity Measures and Outcomes

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Background: Wilson's disease (WD), also known as hepatolenticular or progressive lenticular degeneration, is a rare autosomal recessive inherited disorder of copper metabolism that is characterized by excessive deposition of copper in the liver, brain, and other tissues. Early diagnosis is crucial and treatment may involve medical therapy and even liver transplant. Limited epidemiological data exists on the number of hospitalizations, demographic variations, cost of care, comorbidity measures, and outcomes associated with WD in the US. Methods: We analyzed the National Inpatient Sample (NIS) database for all hospitalizations with WD (ICD‐ 9 code 275.1) as primary or secondary diagnosis during the period from 2001‐2012. Nationwide Inpatient Sample (NIS) is the largest all‐payer inpatient care database in the United States, containing data on more than seven million hospital stays. Its large sample size is ideal for developing national and regional estimates and enables analyses of rare conditions, uncommon treatments, and special populations. Statistical significance of variation in the number of hospitalizations, demographic variations, cost of care, comorbidity measures, and outcomes during the study period were determined using Cochran‐Armitage trend test. Results: Between 2001 and 2012, hospitalizations with WD increased from 671 to 2180 (p < 0.0001, figure 1A). Hospitalizations with WD remained more common in women (p = 0.46), age groups 35‐64 (p < 0.0001), and Caucasians (p = 0.18) throughout the study period. Except in 2005 when Midwest had the highest proportion of WD hospitalizations, Southern US had the greatest proportion of hospitalizations with WD between 2001 and 2012 (p < 0.0001, figure 1B). Every year throughout the study period, more than two thirds of these hospitalizations were recorded at urban teaching centers as compared to urban non‐teaching and rural facilities (p = 0.003). Although length of stay and in‐hospital mortality did not show significant variation, ranging between 5.6‐8.7 days (p = 0.61) and 0.7‐ 4.6% (p = 0.49, figure 1C) respectively, cost of care associated with WD showed a significant rise from $36,581 in 2001 to $74,507 in 2012 (adjusted for inflation, p < 0.0001, figure 1D). Analysis of the Agency for Healthcare Research and Quality (AHRQ) comorbidity measures revealed that hypertension, renal failure, anemia, and psychiatric disorders remained the most commonly associated comorbidities with WD, proportional trends of which only increased throughout the study period (p < 0.0001, figure 1E). Conclusion: A significant rise in the number of WD related hospitalizations with interesting demographic variations, strengthening association with comorbidities and upsurge in cost of care was seen during the study period. Further studies are needed to identify factors responsible for such trends to better elucidate our findings.


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