OBJECTIVES: To describe and compare two methods of ustekinumab drug utilization evaluation in pharmacy claims.  METHODS: Method I (fill pattern) was a drug utilization assessment based on unadjusted raw claims. The National Drug Code, quantity, days supplied, and cost of prescription were used. Method II (dosing pattern) enhanced Method I by combining information on the current claim with information on time to next prescription.  This enhancement accounted for multiple vials/syringes dispensed in a single claim to cover two doses. Only patients with ≥2 ustekinumab prescriptions and meeting dosing algorithm requirements were eligible for Method II. A comparison of dosing results from Wolters Kluwer Source® Lx, across the first three ustekinumab prescriptions, was used for illustration. Calculated ustekinumab cost per injection was based on Wholesale Acquisition Cost (effective 7/5/2011) of $5,485.22 per 45mg and distribution of 45 mg and 90 mg dosing events.  RESULTS: Data from 1039 patients were evaluated in Method I.  A subgroup of patients (N=473) eligible for evaluation under Method II was also evaluated under Method I, to assess differences in results compared with the overall population. Method I yielded higher dose estimates when compared to Method II. This was consistent for the total sample and subgroup. Ustekinumab cost per injection in Method I was estimated up to 68.2% higher than in Method II.  Variability in cost estimates across doses was up to 18 times higher in Method I than Method II.   CONCLUSIONS: Conducting ustekinumab drug utilization assessments with pharmacy claims requires a methodological adjustment to address multiple doses dispensed on the same claim. Unadjusted assessment may yield artificially high dose and cost estimates. Adjusted assessments offer a more realistic distribution of dose and less variability in cost estimates. The ability to conduct adjusted assessments requires the sample to have ≥ 2 ustekinumab prescriptions and sufficient follow-up time.