Effect of nitrate withdrawal on quality of life and adherence to treatment in patients with stable angina

BACKGROUND: Long-term nitrate treatment of stable angina is associated with side effects that can interfere with health-related quality of life (HRQoL) and medication adherence. The aim of the present study was to compare HRQoL and adherence to treatment in patients with stable angina undergoing nitrate withdrawal or maintenance. METHODS: This study is a randomized clinical trial. Patients were allocated to an intervention group (nitrate withdrawal followed by introduction of placebo) or a control group (nitrate maintenance). The assessments were made at baseline and 30 and 120 days using the Short Form Health Survey and the Seattle Angina Questionnaire. Treatment adherence was measured on the basis of the Morisky scale and pill count. RESULTS: A total of 105 patients with stable angina were randomized for replacement of nitrate with placebo (n=51) and for maintenance of treatment with nitrate (n=54). After 4 months, Short Form Health Survey scores increased for bodily pain (P=0.005) and general health (P=0.004) in the nitrate maintenance group. Decreased Seattle Angina Questionnaire scores were also noted for physical limitations (P=0.039) and angina frequency (P=0.011) in the nitrate maintenance group. However, the effect size was small (≤0.44) when the intervention and control groups were compared. At the end of the study, adherence was significantly higher in the placebo group (P=0.041), but no difference was detected between the groups with the pill count method. CONCLUSION: HRQoL was similar in patients with stable angina using nitrate regularly as compared with patients undergoing nitrate withdrawal. However, adherence to treatment was lower in nitrate users according to the Morisky scale.