Abstract Background/Aims Cyclophosphamide is a potent alkylating agent used to manage life- and organ-threatening complications from systemic autoimmune rheumatic diseases (SARDs). It carries a risk of infertility due to its gonadotoxic effects in both men and women. In women, it can lead to premature ovarian failure, early menopause and infertility. The risk increases with patients’ age, cyclophosphamide dosage and number of cycles. Although previous research has focused on clinical endpoints (such as amenorrhea and changes in biomarkers of ovarian reserves after cyclophosphamide), understanding patient perspectives on the information they received for cyclophosphamide treatment and changes in menstruation is important for informed decision-making, fertility planning and patient-centred care. The objective of this study is to examine patient-reported impact of cyclophosphamide on menstruation by age, and to understand patients’ satisfaction with fertility-related information for cyclophosphamide treatment. Methods A cross-sectional international survey was conducted between December 2024 to March 2025 among women with autoimmune diseases who had received cyclophosphamide. Data were collected on age at first exposure, treatment modality, effects on menstrual cycles, and satisfaction with cyclophosphamide counselling. Summary statistics and logistic regression were used for analysis. Results Of the N = 191 SARD participants who had received cyclophosphamide, the majority had vasculitis (41.9%) or lupus (38.7%), with 67% of the respondents reporting being pre-menopausal at the time of cyclophosphamide treatment. A majority (86.3%) received cyclophosphamide regimens after the year 2000. Logistic regression showed that age was significantly associated with the cessation of menstruation, with an odds ratio of 1.21 (95% CI: 1.13-1.30, p 0.001). For each additional year of age, the odds of cessation of menstruation increased by approximately 21%. The proportion of non-menopausal women experiencing secondary amenorrhea after cyclophosphamide treatment increased with age, from 6.4% at ages 30-34, to 37.5% at 35-39, 41.2% at 40-44, and 60.9% at 45-49. The majority (85.3%) of respondents aged 50+ were postmenopausal at the time of treatment. Amongst patients who were pre-menopausal during (first) cyclophosphamide treatment, 46.1% reported that they were satisfied with fertility-related information provided to them before treatment. However, most patients reported having received no information on the option of freezing eggs before treatment (63.4%), or on the possibility of using hormones to protect their ovaries (69.6%). Conclusion The self-reported impact of cyclophosphamide on menstruation amongst patients with SARDs is age-dependent, with increased permanent cessation of menstruation with increased age at first exposure. Results highlight the need for greater information, education and communication for patients on their fertility risk as a routine part of cyclophosphamide treatment pathways. Strengthening the communication between clinicians and patients will help ensure that patients are not left uncertain about the consequences of cyclophosphamide treatment and can make informed choices that align with their reproductive goals. Disclosure K. Naidu: Grants/research support; K.K.N. has received funding for research from The Lupus Trust. Z. Mclaren: None. L. Andreoli: Consultancies; LA has received consultancy fees from Pfizer, UCB, speaker fees from Abbott. A. Kaul: None. D. D’Cruz: Consultancies; DD’C consultancy/speaker fees from GSK, Eli Lilly, and UCB; and a leadership role on the board of APS support UK. Grants/research support; DD’C reports grants from MRC, NIHR, LUPUS UK, and The Lupus Trust. V. Talaulikar: None. S. Taylor: Grants/research support; ST reports funding from The Lupus Trust, LUPUS UK and Vasculitis UK. W. Diment: None. F. Naughton: None. T. Reilly: Grants/research support; TJR is supported by an MRC Clinical Research Training Fellowship, MR/W015943/1. L. Gallagher: None. L. Holloway: None. E. Tranah: None. M.A. Sloan: Consultancies; MS reports consultancy fees from SRUK and Otoimmune. Grants/research support; MS is funded by the NIHR, The Lupus Trust, LUPUS UK, Vasculitis UK.
Naidu et al. (2026) studied this question.