Cost of stress urinary incontinence - A claims data analysis

Objectives: The primary objectives of this research were to: (i) identify and present methodologies for estimating three types of 'cost-of-illness' measures using healthcare and disability claims data-specifically 'cost of treatment', 'incremental cost of patient', and 'incremental cost of illness'; and (ii) perform a case-study analysis of these cost measures for women treated for stress urinary incontinence (SUI). Study Design and Methods: In this paper, we discuss aspects of cost-of-illness methodologies in the context of SUI. We first distinguish between 'cost of treatment' (i.e. the costs of treating a specific condition), 'incremental cost of patient' (i.e. the additional costs associated with patients with a particular condition, irrespective of any comorbid conditions they may also have), and 'incremental cost of illness' (i.e. the additional costs resulting from a particular illness, as distinct from the costs of other conditions that the patient might have, including conditions which might have caused the illness in question). The latter case is in many ways the most complex to model, requiring controls for related causal conditions. We then applied these three methodologies by analysing the costs associated with SUI. Using data from a large employer claims database (n>100 000), we estimated a series of regression models that reflected cost of treatment, incremental cost of patient, and incremental cost of illness for SUI. Results: The three approaches yielded substantially different results. For many purposes the incremental cost-of-illness model provides the most appropriate results, as it controls for comorbid conditions, as well as patient demographics. On a per capita basis using the incremental cost-of-illness model, patients with SUI had direct costs that were 134% more than those for their controls and indirect costs that were 163% more than those for controls. Estimating costs for the average (i.e. mean) person results in dollar-termed estimates of the costs of SUI. In particular, we found that in 1998, the average direct medical cost of SUI was $US5642 and the indirect workplace cost of SUI was $US4208. Conclusions: Since the various methods yield substantially different results, it is important that the end user of cost-of-illness analyses of claims data have a clear purpose in mind when reporting the cost of the condition of concern. The incremental cost-of-illness measure for claims data has substantial advantages in terms of enhancing our understanding of the specific cost impact of SUI.