Effects of vildagliptin/metformin therapy on patient-reported outcomes: work productivity, patient satisfaction, and resource utilization.
INTRODUCTION
Type 2 diabetes mellitus (T2DM) is associated not only with high direct healthcare costs, but also with indirect costs, as diabetic complications and the disease itself result in loss of productivity. Vildagliptin is a novel dipeptidyl peptidase-4 inhibitor that is given either alone or in combination with oral hypoglycemic drugs, including metformin. The study was designed to assess the hypothesis that fixed-combination vildagliptin/metformin improves work productivity measured as Work Productivity and Activity Impairment (WPAI) scores. Secondary objectives were the assessment of patient satisfaction by means of the Diabetes Treatment Satisfaction Questionnaire (DTSQs), the change in anthropometric measurements and in glucose control (glycated hemoglobin [HbA1c]), and the evaluation of resource utilization (Resources Utilization Questionnaire).


METHODS
This study was an addendum to a mandatory, prospective, observational study carried out by the Italian Medicines Agency (Agenzia Italiana del Farmaco [AIFA]) in 49 diabetes centers in Italy. The addendum included 1,046 adult outpatients with a diagnosis of T2DM, who were no longer responding to metformin monotherapy. Patients were observed for up to 1 year.


RESULTS
Mean activity impairment improved by 40.6% (15.4±17.4 vs. 26.1±24.4; P<0.0001), absenteeism by 49.9% (2.0±9.4 vs. 3.8±13.3; P=0.0076), and total work productivity by 37.6% (14.9±15.9 vs. 21.5±24.6; P<0.0001). This resulted in a reduction of the annual indirect cost due to impaired productivity of €400 per working patient and €135 per patient in general. The DTSQ score increased by 30.2% (29.6±5.6 vs. 22.8±6.9; P<0.0001). The satisfaction rate increased from baseline by 44.7%; the hyperglycemia-free or almost hyperglycemia-free perception rate by 37.9%; and the hypoglycemia-free or almost hypoglycemia-free rate by 15.2%. Mean healthcare costs per patients diminished by 19.2% in the second semester of treatment.


CONCLUSION
This observational study suggests that the fixed combination of vildagliptin/ metformin increases work productivity, reducing indirect costs, and improves quality of life, especially in terms of perception of blood glucose variability, in patients with T2DM.