Outcomes of Treatment Modifications of Antihypertensive Regimens

Abstract

Antihypertensive treatment modifications (TMs)—addition, uptitration, switching, and downtitration–often are necessary to address issues such as unattained blood pressure (BP) goals, adverse drug events, drug cost, or patient dissatisfaction with first-line treatment. Despite a high prevalence, our understanding of TMs is limited. The objectives of this dissertation were: (a) to assess the patterns of TMs, (b) to compare adherence across the TM strategies and assess the factors associated with adherence, and (c) to compare the healthcare costs across TM strategies and understand its association with adherence. A retrospective cohort study of the BlueCross-BlueShield of Texas claims database (2008-2012) was conducted. A total of 21,642 newly treated patients were followed for 12 months to determine if and when they received a TM. Adherence (measured as proportion of days covered (PDC)) and costs were compared over a 12-month duration. Cox regression models were used to determine the likelihood of TM and discontinuation, while generalized linear models were used to compare adherence and costs. About 48.5% of patients received TMs within one year of initiating treatment. Rates of TM were significantly different across drug classes (P<0.05). Patients adding medications were about 25% (vs. uptitration) and 50% (vs. switching) less likely to discontinue treatment. Adherence was lowest in the addition group (mean=0.68 ± 0.27). The odds of adherence was lower for the free-pill combination (FPC) group but higher for the fixed-dose combination (FDC) group compared to other TM strategies (P<0.05). The total all-cause annual healthcare costs were higher for addition and downtitration compared to other competing strategies (P<0.001). Drug costs were higher for addition compared to alternative strategies (P<0.0001). However, the costs of hypertension and cardiovascular-related inpatient visits were lower for the FDC group compared to the uptitration ($11,348.8 lower; P=0.004) and switching ($2,655.41 lower; P=0.19) groups. Overall, the use of FDCs appear to be an advantageous intensification strategy while switching of medication may be a preferred approach over downtitration. Further research is required to understand the long-term cost-effectiveness of alternative TM strategies and the actual relationship of these findings with BP control and long-term outcomes.