Healthcare Resource Use, Costs, and Disease Progression Associated with Diabetic Nephropathy in Adults with Type 2 Diabetes: A Retrospective Observational Study

Introduction: Diabetic nephropathy (DN) is a progressive kidney disease resulting as a complication of diabetes mellitus. This study evaluated the disease progression and economic burden of DN among commercially insured patients with type 2 diabetes in the USA. Methods: The research design was a retrospective observational study based on healthcare claims data. The Truven MarketScan Databases (2004-2014) were queried for adults with type 2 diabetes with at least one urine albumin test (index, randomly selected) after diagnosis and at least one test after the index. On the basis of the index test, patients were classified into normoalbuminuria, microalbuminuria, or macroalbuminuria groups. Nephropathy-related treatment use was measured in the 6 months after the index, disease progression was assessed from the index to the end of data availability, and annual all-cause and nephropathy-related costs and healthcare resource use (HRU) were assessed up to 2 years from the index. Outcomes were compared between any two groups, controlling for baseline demographics. Results: A total of 23,235 patients were identified and classified into normoalbuminuria (N = 18,409), microalbuminuria (N = 3863), or macroalbuminuria (N = 963) groups. Patients with albuminuria were more likely to be older, male, and have a higher burden of baseline comorbidities and HRU. Within 6 months following the index, 12-20% of patients with albuminuria were not treated with any relevant recommended treatment. Compared to the normoalbuminuria group, patients with macroalbuminuria had a significantly greater risk of disease progression (hazard ratio [HR] = 1.44), and both albuminuria groups were more likely to require dialysis (HR = 4.23 and 40.14 for micro- and macroalbuminuria, respectively; all p < 0.05). Annual all-cause (2016 US dollars, $3580 and $12,830 higher for micro- and macroalbuminuria vs. normoalbuminuria, respectively) and nephropathy-related ($362 and $3716) costs increased significantly with increasing nephropathy severity, consistent with the trend in increased HRU. Conclusions: Diabetic nephropathy may be undertreated or inappropriately treated. It was also associated with significantly higher costs, HRU, and risk of disease progression among commercially insured patients with type 2 diabetes in the USA.