Compliance with pharmacotherapy and direct healthcare costs in patients with Parkinson's disease: a retrospective claims database analysis

Abstract

Background: Parkinson's disease (PD) is a progressive neurological disorder for which, at present, there is no cure. Current therapy is largely based on the use of dopamine agonists and dopamine replacement therapy, designed to control the signs and symptoms of the disease. The majority of current treatments are administered in tablet form and can involve multiple daily doses, which may contribute to sub-optimal compliance. Previous studies with small groups of patients suggest that non-compliance with treatment can result in poor response to therapy and may ultimately increase direct and indirect healthcare costs.

Objective: To determine the extent of non-compliance within the general PD population in the USA as well as the patient characteristics and healthcare costs associated with compliance and non-compliance.

Methods: A retrospective analysis from a managed care perspective was conducted using data from the USA PharMetrics patient-centric claims database. PharMetrics claims data were complete from 31 December 2005 to 31 December 2009. Patients were included if they had at least two diagnoses for PD between 31 December 2005 and 31 December 2008, were older than 18 years of age, were continuously enrolled for at least 12 months after the date of the most recent PD diagnosis, and had no missing or invalid data. The follow-up period was the most recent 12-month block of continuous enrollment that occurred between 2006 and 2009. Patients were required to have at least one PD-related prescription within the follow-up period. The medication possession ratio (MPR) was used to categorise patients as compliant or non-compliant. Direct all-cause annual healthcare costs for patients with PD were estimated for each patient, and regression analyses were conducted to determine predictors for non-compliance.

Results: A total of 15,846 patients were included, of whom 46 % were considered to be non-compliant with their prescribed medication (MPR <0.8). Predictors of non-compliance included prescription of a medication administered in multiple daily doses (p < 0.0001), a period of <2 years since the initial PD diagnosis (p = 0.0002), a diagnosis of gastrointestinal disorder (p < 0.0001), and a diagnosis of depression (p < 0.0001). Non-compliance was also found to be related to age, with a lower odds of non-compliance in patients aged 41-80 years than in patients aged ≥81 years (p < 0.05). Although total drug mean costs were higher for compliant patients than non-compliant patients (driven mainly by the cost of PD-related medications), the mean costs associated with emergency room and inpatient visits were higher for patients non-compliant with their prescribed medication. Overall, the total all-cause annual healthcare mean cost was lower for compliant ($77,499) than for non-compliant patients ($84,949; p < 0.0001).

Conclusion: Non-compliance is prevalent within the general USA PD population and is associated with a recent PD diagnosis, certain comorbidities, and multiple daily treatment dosing. Non-compliance may increase the burden on the healthcare system because of greater resource usage compared with the compliant population. Treatments that require fewer daily doses may have the potential to improve compliance, which in turn could reduce the economic burden associated with PD.

Fig. 1

Study design indicating index date and follow-up period. All patients were required to have at least one PD-related prescription during the 12-month follow-up period

Fig. 2

Flow chart indicating patient selection from the PharMetrics^® database. PD Parkinson’s disease. * Patients were deleted because of missing or zero values for quantity after last observation carried forward (LOCF) was used. Patients were also excluded if they had PD prescriptions for 50 or more tablets a day

Fig. 3

The mean cost difference between outpatient mean costs, drug mean costs, and non-emergency room hospitalisation mean costs for non-compliant patients minus costs for compliant patients undergoing PD treatment. PD Parkinson’s disease