Kidney involvement in tuberous sclerosis complex: the impact on healthcare resource use and costs

Abstract

Objective:

Tuberous sclerosis complex (TSC) is associated with non-malignant kidney lesions—angiomyolipomata—that may be associated with chronic kidney disease (CKD). This study investigated the relationship between renal angiomyolipomata and CKD in TSC, including the impact on healthcare resource utilization (HCRU) and costs.

Methods:

This was a retrospective, longitudinal cohort study based on medical record data spanning January 1990–April 2012 for 369 TSC patients treated at a specialty center in the Netherlands. Cohorts were established based on CKD stage and angiomyolipoma size. Rates of HCRU (physician visits, monitoring, and interventions) were compared across cohorts using rate ratios. Healthcare costs were compared across cohorts using cost differences. Regression models were used to identify predictive factors for HCRU and healthcare costs.

Results:

Sixteen per cent of patients reached CKD stage 3 or higher during follow-up. Patients at more advanced stages of CKD more frequently had either large or multiple small angiomyolipomata and higher HCRU rates and healthcare costs. In the multivariate analyses, male gender, CKD stage >1, angiomyolipoma size ≥3.5 cm, embolization, and the presence of moderate or severe lymphangioleiomyomatosis (LAM) were associated with greater HCRU (p ≤ 0.002 for all comparisons). Definite (vs suspected) TSC diagnosis, CKD stage 5 (vs CKD stage 1), angiomyolipoma size ≥3.5 cm, and moderate or severe LAM were associated with higher costs (p = 0.050 for TSC diagnosis, p ≤ 0.002 for other comparisons). Costs in CKD stage 5 were driven primarily by dialysis.

Conclusions:

A substantial proportion of patients with TSC developed moderate-to-severe CKD, which was associated with renal angiomyolipomata and increased HCRU and costs.

Keywords::

• Renal angiomyolipoma
• Chronic kidney disease
• Healthcare costs
• Healthcare resource utilization
• Tuberous sclerosis complex

Transparency

Declaration of funding

This study was supported by funding from Novartis Pharmaceuticals Corporation (Novartis). Funding provided by Novartis was not contingent upon the study results.

Declaration of financial/other relationships

Research support was provided to Analysis Group, Inc. by Novartis. FV, PK, and MSD are employees of Analysis Group, Inc. TN was an employee of Analysis Group, Inc. at the time of the study. MM is an employee of Novartis, and SB van W van DK was an employee of Novartis at the time of the study. BZ is an employee of the University Medical Center Utrecht, which received research funding from Novartis for this study. JME peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Acknowledgments

Research idea and study design: BZ, MM, MD; data analysis/interpretation and statistical analysis: FV, PK, TN, MD Each author contributed important intellectual content during manuscript drafting or revision and accepts accountability for the overall work by ensuring that questions pertaining to the accuracy or integrity of any portion of the work are appropriately investigated and resolved. The authors thank Casey Jones of Analysis Group, Inc. for research assistance. All authors take the responsibility that this study has been reported honestly, accurately, and transparently, and that no important aspects of the study have been omitted.