OBJECTIVE: Blood pressure control can be difficult to achieve in hypertension, often requiring combination pharmacotherapy. A variety of approaches are available, including fixed dose combinations (FDC) versus individual components (IC). The purpose of this analysis was to assess combination valsartan and hydrocholorthiazide (HCTZ) therapy in previously antihypertensive naïve patients. METHODS: A national database of insured patients ages 18 & older with hypertension were evaluated for combination valsartan and HCTZ use initiated within 180 days of each other. Patients had at least two claims for this combination of pharmacotherapy within one year of their first prescription. Eligibility included continuous enrollment 110 days prior to first prescription and 365 days following dual therapy. Eligible patients were antihypertensive naïve 110 days prior to study drug initiation. Combination pharmacotherapy persistency at 365 days was calculated and sensitivity analysis was performed for the length of refill gaps. RESULTS: There were 2,022,578 unique patients age18 years or older identified with hypertension ICD-9 codes (401.0, 401.1, 401.9, 402.1 & 402.9). After applying study criteria there were 8,711 eligible patients; 8,150 FDC and 561 IC. In assessing ongoing persistence, patients could not have a refill gap in excess of 120% of previous prescription day's supply. FDC persistency was 54% (4,362/8,150) compared to 19% (109/561) for IC at 365 days (p<.0001). Using a more stringent threshold (80% days supply), FDC was 44% (3,623/8150) vs. IC 16% (91/561) p<.0001. Increasing the threshold (160% days supply) the FDC was 59% (4,821/8150) vs. IC 21% (119/561) p<.0001. CONCLUSIONS: Use of FDC is more common (93.5 %) than individual components for this previously naïve antihypertensive population. The fixed dose combination therapy group was shown to have significantly better persistence at 365 days vs. the individual components group, which proved to be quite robust following a sensitivity analysis.