Adherence to Disease-Modifying Therapies at a Multiple Sclerosis Clinic: The Role of the Specialty Pharmacist.

BACKGROUND: Disease-modifying therapy (DMT) delays disease progression and improves quality of life for patients with multiple sclerosis (MS), but adherence to DMT is often suboptimal. Vanderbilt Specialty Pharmacy (VSP) embeds pharmacists within an outpatient MS clinic to provide medication management and address barriers to adherence. OBJECTIVE: We evaluated rates and predictors of adherence to DMT among patients with MS at an integrated specialty pharmacy. METHODS: We included patients with MS who filled ≥3 DMT prescriptions from VSP during the study period. Adherence was defined as medication possession ratio (MPR) or proportion of days covered (PDC) ≥0.8. Reasons for nonadherence were collected from pharmacy claims and electronic medical records. RESULTS: The study included 653 patients. Average MPR and PDC were 0.93 and 0.94, respectively. Eighty-eight percent of patients achieved MPR ≥0.8; 89% achieved PDC ≥0.8. Using financial assistance and having $0 out-of-pocket cost were associated with higher odds of achieving MPR and PDC ≥0.8 (P < .05). Of the 12% of patients who were nonadherent, most were unreachable for refills. CONCLUSIONS: Ensuring financial assistance and low out-of-pocket costs are associated with high adherence to DMT within an integrated specialty clinic, but more work is needed to address adherence in unreachable patients.

Evaluation of Modification of Diet in Renal Disease Study and Cockcroft-Gault equations for sitagliptin dosing.

BACKGROUND: Assessment of kidney function is necessary to determine appropriate dosing regimens. While the Cockcroft-Gault (CG) equation is used to calculate the estimated creatinine clearance (eCLCr) for drug dosing, the Modification of Diet in Renal Disease (MDRD) Study equation has recently been advocated. Sitagliptin is a dipeptidyl-peptidase IV inhibitor with dose adjustments based on eCLCr. We assessed discordance in sitagliptin doses recommended using MDRD and CG equations. METHODS: Adult patients with type 2 diabetes mellitus were included. Estimated glomerular filtration rate (eGFR) individualized for body surface area (eGFR-BSA) and eCLCr were calculated by the MDRD and CG equations, respectively, and sitagliptin dose was determined. Discordance in doses recommended by method were compared overall and by subgroup based on eCLCr category. RESULTS: A total of 121 patients were included: 52% male, 90% white, mean age 61 ± 12 years, weight 93 ± 19 kg, BSA 2.0 ± 0.22 m2 and body mass index (BMI; calculated as kg/m2) 33 ± 7. Mean eGFR-BSA was 76 ± 19 ml/min and eCLCr was 68 ± 17 ml/min. Discordance in sitagliptin dose was observed in 11 patients (9%) with MDRD compared with CG. All patients with eCLCr =50 would have received a higher dose using MDRD, while patients with eCLCr >50 would have received a lower dose. CONCLUSIONS: Overall there was agreement in sitagliptin dose using MDRD and CG equations. Discrepancies resulted in underestimation of sitagliptin dose at eCLCr above 50 ml/min and overestimation at lower eCLCr. Clinical implications are the potential for excessive dosing of sitagliptin and other agents with similar dose stratification by eCLCr in individuals with kidney dysfunction.