Off-label indications of aspirin in gynaecology and obstetrics outpatients at two Chinese tertiary care hospitals: a retrospective cross-sectional study

Objective To investigate the prevalence of off-label aspirin indications and the level of scientific support for off-label indications of aspirin in gynaecology and obstetrics outpatients. Design A retrospective cross-sectional study. Setting Two tertiary hospitals (a general hospital and a women and children's specialised hospital) in Xiamen, a city located on the southeastern coast of China. Participants A total of 4257 prescriptions were included for 2091 female patients aged >18 who visited the gynaecology and obstetrics outpatient clinics and received aspirin treatment. Outcome measures The primary measure of this study was the proportion of off-label indications and of off-label indications supported by strong scientific evidence. Evidence from clinical guidelines and Micromedex is shown using descriptive statements. On-label indications of drugs in the same class as aspirin were also referred to for off-label aspirin use without strong evidence support. Results All indications of aspirin on outpatient prescriptions were determined as off-label use in this study. The most frequent off-label indication was recurrent miscarriage (2244 prescriptions, 52.71%). Totally, 30.94% of the prescriptions were supported by strong evidence for indications, including recurrent miscarriage with antiphospholipid syndrome and prophylaxis for pre-eclampsia. No drugs in the same class as aspirin had on-label indications for off-label aspirin use without strong evidence support. Conclusions This study demonstrated that all indications of aspirin used in gynaecology and obstetrics outpatients at the two tertiary hospitals were off-label and not always supported by strong evidence, implicating that physicians should be cautious when issuing off-label prescriptions. More original clinical research on off-label aspirin use is needed to provide reference for routine clinical practice.