Units and Costs of Comparable Insulin Supplied to Patients

San Diego—Many companies that supply insulin can offer products with similar pharmacokinetic or pharmacodynamic (PK/PD) properties. This is the case with the active ingredients of insulin products produced by Eli Lilly and Company (LLY) and Novo Nordisk (NN).

As such, it can be hypothesized that patients with similar characteristics will use similar amounts of comparable insulin regardless of the manufacturer, and that any differences in observed units per claim would potentially be due to the differences in patient characteristics. Because comparable LLY and NN insulin products are comparatively priced, it can be assumed that any difference in the overall costs of comparable insulin products will be a function of the differences in patient characteristics.

The authors of a recent study presented their findings during a poster session at the AMCP meeting. The poster was titled Units and Costs of Comparable Insulin Supplied to Patients: Is there a Difference by Manufacturer? The objective of the study was to compare the units per claim per day and costs per claim per day of comparable LLY and NN products supplied in 2011, while adjusting for observable patient characteristics.

For the analysis, de-identified employer claims data were utilized for services provided between January 1, 1999, and September 30, 2011, for approximately 16 million beneficiaries from 60 large, self-insured Fortune 500 companies in the United States. Data contained information on enrollment history, patient demographics, medical and prescription drug claims, and costs (measured as payments to providers by insurers). Patients in the study had to have at least 1 claim in 2011 for LLY or NN insulin products.

Patients were separated into 2 groups (<65 years of age and ≥65 years of age) and stratified by demographics, type of health insurance, select comorbidities, Charlson comorbidity index, endocrinologist visits, insulin pump use, and antidiabetic medication use. For all claims for comparable insulin products in 2011, units per claim per day (PCPD) were calculated by multiplying total quantity per claim (in mL) by strength (1 mL=100 units) and dividing by total days supplied. Costs PCPD were calculated by dividing the cost of a claim to insurers by total days supplied. Mean units and costs were compared within each age group for overall cost (all claims for comparable products), vials for comparable products, pens for comparable products, and by comparable product.

The majority of patients (n=24,616 in the LLY group; n=20,705 in NN group) using insulin products were enrolled in a PPO health plan (42.6% vs 44.6% among all patients with LLY vs NN insulin and 58.9 vs 61.7% among those <65 years of age). Among patients ≥65 years of age, however, more were enrolled in indemnity (42.5% vs 40.5%) or HMO (31.0% vs 35.0%) health plans.

At baseline, fewer patients using LLY insulin were diagnosed with comorbid conditions (with the exception of retinopathy) and had significantly lower CCI (excluding diabetes) than those using comparable NN products in all age groups. After adjusting for differences in baseline patient characteristics, the mean number of insulin units PCPD were similar for all comparable LLY and NN products with the exception of significantly lower units PCPD for LLY human insulin isophane vial vs NN human insulin isophane vial, and for LLY regular human insulin vial vs NN regular human insulin vial.

Among those <65 years of age, the mean units PCPD for all comparable LLY and NN insulin products were similar after adjusting for baseline differences. The regression-adjusted overall cost of LLY insulin claims was significantly lower than comparable NN insulin. This was likely because proportionally more LLY claims were for vials, which were less expensive than pens. Results were similar for those ≥65 years of age.

This study was supported by Eli Lilly and Company.